Create RB-2.3.2 release (#1940 )

* Fix ssse3 detection typo (#1929) Signed-off-by: Mark Reid <mindmark@gmail.com> (cherry picked from commit 003b6a19e6) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * fix: use system `include pystring.h` for `ConfigUtils.cpp` (#1921) Signed-off-by: Rui Chen <rui@chenrui.dev> Co-authored-by: Doug Walker <doug.walker@autodesk.com> (cherry picked from commit e747e9c0bd) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * Fix narrowing conversion error on riscv64 (#1924) Signed-off-by: phancb <nxhsdu@qq.com> Co-authored-by: Doug Walker <doug.walker@autodesk.com> (cherry picked from commit a95febc70e) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * Add manylinux_2_28 Python wheels (#1933) Signed-off-by: Rémi Achard <remiachard@gmail.com> Co-authored-by: Michael Dolan <michdolan@gmail.com> Co-authored-by: Doug Walker <doug.walker@autodesk.com> (cherry picked from commit f9250992eb) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * Enhance ociochecklut to print the output after each step in a multi-t… (#1925) * Enhance ociochecklut to print the output after each step in a multi-transform LUT Signed-off-by: pylee <penne.y.lee@intel.com> * Review feedback to enable printe of transforms list when using -s flag. Signed-off-by: pylee <penne.y.lee@intel.com> * Print transform description for each step instead. Signed-off-by: pylee <penne.y.lee@intel.com> --------- Signed-off-by: pylee <penne.y.lee@intel.com> Co-authored-by: Doug Walker <doug.walker@autodesk.com> (cherry picked from commit aadf595946) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * Fix AVX instructions used on CPUs that don't support them (#1935) * Fix AVX instructions used on CPUs that don't support them It's supposed to check all bits are enabled, not just one of them. This causes a crash using OpenColorIO on older CPUs. Thanks to Ray Molenkamp for help tracking this down. Signed-off-by: Brecht Van Lommel <brecht@blender.org> * Fix another case pointed out in review Signed-off-by: Brecht Van Lommel <brecht@blender.org> --------- Signed-off-by: Brecht Van Lommel <brecht@blender.org> (cherry picked from commit 0c90ded166) Signed-off-by: Doug Walker <doug.walker@autodesk.com> * Increment library version to 2.3.2 Signed-off-by: Doug Walker <doug.walker@autodesk.com> --------- Signed-off-by: Mark Reid <mindmark@gmail.com> Signed-off-by: Doug Walker <doug.walker@autodesk.com> Signed-off-by: Rui Chen <rui@chenrui.dev> Signed-off-by: phancb <nxhsdu@qq.com> Signed-off-by: Rémi Achard <remiachard@gmail.com> Signed-off-by: pylee <penne.y.lee@intel.com> Signed-off-by: Brecht Van Lommel <brecht@blender.org> Co-authored-by: Mark Reid <mindmark@gmail.com> Co-authored-by: Rui Chen <rui@chenrui.dev> Co-authored-by: phanium <91544758+phanen@users.noreply.github.com> Co-authored-by: Rémi Achard <remiachard@gmail.com> Co-authored-by: Michael Dolan <michdolan@gmail.com> Co-authored-by: PenneLee <penne.y.lee@intel.com> Co-authored-by: Brecht Van Lommel <brecht@blender.org>
Integrate main into RB-2.3 branch and update library version (#1918 )
2024-01-30 02:11:35 -05:00 · 2023-12-07 20:02:08 -05:00
145 changed files with 5810 additions and 725 deletions
@@ -77,6 +77,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2023
+            install-ext-packages: MISSING
          - build: 11
            build-type: Release
            build-shared: 'ON'
@@ -89,6 +90,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2023
+            install-ext-packages: ALL
          - build: 10
            build-type: Release
            build-shared: 'OFF'
@@ -101,6 +103,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2023
+            install-ext-packages: ALL
          # -------------------------------------------------------------------
          # VFX CY2022 (Python 3.9)
          # -------------------------------------------------------------------
@@ -116,6 +119,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2022
+            install-ext-packages: ALL
          - build: 8
            build-type: Release
            build-shared: 'ON'
@@ -128,6 +132,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2022
+            install-ext-packages: MISSING
          - build: 7
            build-type: Release
            build-shared: 'OFF'
@@ -140,6 +145,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2022
+            install-ext-packages: ALL
          # -------------------------------------------------------------------
          # VFX CY2021 (Python 3.7)
          # -------------------------------------------------------------------
@@ -155,6 +161,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2021
+            install-ext-packages: MISSING
          - build: 5
            build-type: Release
            build-shared: 'OFF'
@@ -167,6 +174,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2021
+            install-ext-packages: ALL
          - build: 4
            build-type: Debug
            build-shared: 'ON'
@@ -179,6 +187,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2021
+            install-ext-packages: ALL
          # -------------------------------------------------------------------
          # VFX CY2020 (Python 3.7)
          # -------------------------------------------------------------------
@@ -194,6 +203,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2020
+            install-ext-packages: MISSING
          - build: 2
            build-type: Debug
            build-shared: 'OFF'
@@ -206,6 +216,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2020
+            install-ext-packages: ALL
          - build: 1
            build-type: Release
            build-shared: 'ON'
@@ -218,6 +229,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2020
+            install-ext-packages: ALL
    env:
      CXX: ${{ matrix.cxx-compiler }}
      CC: ${{ matrix.cc-compiler }}
@@ -245,7 +257,7 @@ jobs:
                -DOCIO_BUILD_GPU_TESTS=OFF \
                -DOCIO_USE_SIMD=${{ matrix.use-simd }} \
                -DOCIO_USE_OIIO_FOR_APPS=${{ matrix.use-oiio }} \
-                -DOCIO_INSTALL_EXT_PACKAGES=ALL \
+                -DOCIO_INSTALL_EXT_PACKAGES=${{ matrix.install-ext-packages }} \
                -DOCIO_WARNING_AS_ERROR=ON \
                -DPython_EXECUTABLE=$(which python)
        working-directory: _build
@@ -527,7 +539,10 @@ jobs:
      - name: Checkout
        uses: actions/checkout@v3
      - name: Install docs env
-        run: share/ci/scripts/windows/install_docs_env.sh
+        run: |
+          DOXYGEN_PATH=$GITHUB_WORKSPACE/doxygen
+          share/ci/scripts/windows/install_docs_env.sh "$DOXYGEN_PATH"
+          echo "$DOXYGEN_PATH" >> $GITHUB_PATH
        shell: bash
        if: matrix.build-docs == 'ON'
      - name: Install tests env
@@ -54,6 +54,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2022
+            use-oiio: 'ON'
          - build: 2
            build-docs: 'OFF'
            build-openfx: 'OFF'
@@ -62,6 +63,7 @@ jobs:
            cc-compiler: gcc
            compiler-desc: GCC
            vfx-cy: 2021
+            use-oiio: 'OFF'
          # -------------------------------------------------------------------
          # Clang
          # -------------------------------------------------------------------
@@ -73,6 +75,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2022
+            use-oiio: 'OFF'
          - build: 4
            build-docs: 'ON'
            build-openfx: 'ON'
@@ -81,6 +84,7 @@ jobs:
            cc-compiler: clang
            compiler-desc: Clang
            vfx-cy: 2021
+            use-oiio: 'ON'
    env:
      CXX: ${{ matrix.cxx-compiler }}
      CC: ${{ matrix.cc-compiler }}
@@ -132,7 +136,7 @@ jobs:
                -DOCIO_INSTALL_EXT_PACKAGES=NONE \
                -DOCIO_WARNING_AS_ERROR=OFF \
                -DPython_EXECUTABLE=$(which python) \
-                -DOCIO_USE_OIIO_CMAKE_CONFIG=ON
+                -DOCIO_USE_OIIO_FOR_APPS=${{ matrix.use-oiio }}
        working-directory: _build
      - name: Build
        run: |
@@ -176,11 +180,13 @@ jobs:
            build-openfx: 'ON'
            cxx-standard: 17
            python-version: '3.11'
+            use-oiio: 'ON'
          - build: 2
            build-docs: 'ON'
            build-openfx: 'ON'
            cxx-standard: 14
            python-version: '3.9'
+            use-oiio: 'OFF'
    steps:
      - name: Setup Python
        uses: actions/setup-python@v4
@@ -235,7 +241,7 @@ jobs:
                -DOCIO_INSTALL_EXT_PACKAGES=NONE \
                -DOCIO_WARNING_AS_ERROR=OFF \
                -DPython_EXECUTABLE=$(which python) \
-                -DOCIO_USE_OIIO_CMAKE_CONFIG=ON
+                -DOCIO_USE_OIIO_FOR_APPS=${{ matrix.use-oiio }}
        working-directory: _build
      - name: Build
        run: |
@@ -279,11 +285,13 @@ jobs:
            build-openfx: 'ON'
            cxx-standard: 17
            python-version: '3.11'
+            use-oiio: 'ON'
          - build: 2
            build-docs: 'ON'
            build-openfx: 'ON'
            cxx-standard: 14
            python-version: '3.9'
+            use-oiio: 'OFF'
    steps:
      - name: Setup Python
        uses: actions/setup-python@v4
@@ -292,7 +300,10 @@ jobs:
      - name: Checkout
        uses: actions/checkout@v3
      - name: Install docs env
-        run: share/ci/scripts/windows/install_docs_env.sh
+        run: |
+          DOXYGEN_PATH=$GITHUB_WORKSPACE/doxygen
+          share/ci/scripts/windows/install_docs_env.sh "$DOXYGEN_PATH"
+          echo "$DOXYGEN_PATH" >> $GITHUB_PATH
        shell: bash
        if: matrix.build-docs == 'ON'
      - name: Install tests env
@@ -359,7 +370,7 @@ jobs:
                -DOCIO_WARNING_AS_ERROR=OFF \
                -DPython_EXECUTABLE=$(which python) \
                -DOCIO_BUILD_PYTHON=OFF \
-                -DOCIO_USE_OIIO_CMAKE_CONFIG=ON
+                -DOCIO_USE_OIIO_FOR_APPS=${{ matrix.use-oiio }}
        shell: bash
        working-directory: _build
      - name: Build
@@ -16,8 +16,6 @@ on:
    tags-ignore:
      - v0.*
      - v1.*
-    paths:
-      - .github/workflows/gpu_workflow.yml

 jobs:
  # ---------------------------------------------------------------------------
@@ -104,7 +104,7 @@ jobs:
                -DOCIO_BUILD_OPENFX=ON \
                -DOCIO_BUILD_GPU_TESTS=OFF \
                -DOCIO_BUILD_PYTHON=${{ matrix.build-python}} \
-                -DOCIO_USE_SSE=ON \
+                -DOCIO_USE_SIMD=ON \
                -DOCIO_USE_OIIO_FOR_APPS=OFF \
                -DOCIO_INSTALL_EXT_PACKAGES=ALL \
                -DOCIO_WARNING_AS_ERROR=ON \
@@ -219,7 +219,7 @@ jobs:
                -DOCIO_BUILD_OPENFX=ON \
                -DOCIO_BUILD_GPU_TESTS=OFF \
                -DOCIO_BUILD_PYTHON=${{ matrix.build-python}} \
-                -DOCIO_USE_SSE=ON \
+                -DOCIO_USE_SIMD=ON \
                -DOCIO_USE_OIIO_FOR_APPS=OFF \
                -DOCIO_INSTALL_EXT_PACKAGES=ALL \
                -DOCIO_WARNING_AS_ERROR=ON \
@@ -333,7 +333,7 @@ jobs:
                -DOCIO_BUILD_OPENFX=ON \
                -DOCIO_BUILD_GPU_TESTS=OFF \
                -DOCIO_BUILD_PYTHON=${{ matrix.build-python}} \
-                -DOCIO_USE_SSE=ON \
+                -DOCIO_USE_SIMD=ON \
                -DOCIO_USE_OIIO_FOR_APPS=OFF \
                -DOCIO_INSTALL_EXT_PACKAGES=ALL \
                -DOCIO_WARNING_AS_ERROR=ON \
@@ -78,41 +78,86 @@ jobs:
      matrix:
        include:
          # -------------------------------------------------------------------
-          # CPython 64 bits
+          # CPython 64 bits manylinux_2_28
          # -------------------------------------------------------------------
-          - build: CPython 3.7 64 bits
+          - build: CPython 3.7 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
            python: cp37-manylinux*
            arch: x86_64
-          - build: CPython 3.8 64 bits
+          - build: CPython 3.8 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
            python: cp38-manylinux*
            arch: x86_64
-          - build: CPython 3.9 64 bits
+          - build: CPython 3.9 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
            python: cp39-manylinux*
            arch: x86_64
-          - build: CPython 3.10 64 bits
+          - build: CPython 3.10 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
            python: cp310-manylinux*
            arch: x86_64
-          - build: CPython 3.11 64 bits
+          - build: CPython 3.11 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
            python: cp311-manylinux*
            arch: x86_64
+          - build: CPython 3.12 64 bits manylinux_2_28
+            manylinux: manylinux_2_28
+            python: cp312-manylinux*
+            arch: x86_64
          # -------------------------------------------------------------------
-          # CPython ARM 64 bits
+          # CPython 64 bits manylinux2014
          # -------------------------------------------------------------------
-          - build: CPython 3.7 ARM 64 bits
+          - build: CPython 3.7 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp37-manylinux*
+            arch: x86_64
+          - build: CPython 3.8 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp38-manylinux*
+            arch: x86_64
+          - build: CPython 3.9 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp39-manylinux*
+            arch: x86_64
+          - build: CPython 3.10 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp310-manylinux*
+            arch: x86_64
+          - build: CPython 3.11 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp311-manylinux*
+            arch: x86_64
+          - build: CPython 3.12 64 bits  manylinux2014
+            manylinux: manylinux2014
+            python: cp312-manylinux*
+            arch: x86_64
+          # -------------------------------------------------------------------
+          # CPython ARM 64 bits manylinux2014
+          # -------------------------------------------------------------------
+          - build: CPython 3.7 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
            python: cp37-manylinux*
            arch: aarch64
-          - build: CPython 3.8 ARM 64 bits
+          - build: CPython 3.8 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
            python: cp38-manylinux*
            arch: aarch64
-          - build: CPython 3.9 ARM 64 bits
+          - build: CPython 3.9 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
            python: cp39-manylinux*
            arch: aarch64
-          - build: CPython 3.10 ARM 64 bits
+          - build: CPython 3.10 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
            python: cp310-manylinux*
            arch: aarch64
-          - build: CPython 3.11 ARM 64 bits
+          - build: CPython 3.11 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
            python: cp311-manylinux*
            arch: aarch64
+          - build: CPython 3.12 ARM 64 bits manylinux2014
+            manylinux: manylinux2014
+            python: cp312-manylinux*
+            arch: aarch64

    steps:
      - uses: actions/checkout@v3
@@ -128,10 +173,12 @@ jobs:
          platforms: all

      - name: Build wheels
-        uses: pypa/cibuildwheel@v2.13.1
+        uses: pypa/cibuildwheel@v2.16.2
        env:
          CIBW_BUILD: ${{ matrix.python }}
          CIBW_ARCHS: ${{ matrix.arch }}
+          CIBW_MANYLINUX_X86_64_IMAGE: ${{ matrix.manylinux }}
+          CIBW_MANYLINUX_AARCH64_IMAGE: ${{ matrix.manylinux }}

      - uses: actions/upload-artifact@v3
        with:
@@ -143,7 +190,7 @@ jobs:

  macos:
    name: Build wheels on macOS
-    runs-on: macos-11
+    runs-on: macos-12
    # Don't run on OCIO forks
    if: |
      github.event_name != 'schedule' ||
@@ -169,6 +216,9 @@ jobs:
          - build: CPython 3.11 64 bits
            python: cp311-*
            arch: x86_64
+          - build: CPython 3.12 64 bits
+            python: cp312-*
+            arch: x86_64
          # -------------------------------------------------------------------
          # CPython ARM 64 bits
          # -------------------------------------------------------------------
@@ -184,6 +234,9 @@ jobs:
          - build: CPython 3.11 ARM 64 bits
            python: cp311-*
            arch: arm64
+          - build: CPython 3.12 ARM 64 bits
+            python: cp312-*
+            arch: arm64

    steps:
      - uses: actions/checkout@v3
@@ -194,7 +247,7 @@ jobs:
          python-version: '3.8'

      - name: Build wheels
-        uses: pypa/cibuildwheel@v2.13.1
+        uses: pypa/cibuildwheel@v2.16.2
        env:
          CIBW_BUILD: ${{ matrix.python }}
          CIBW_ARCHS: ${{ matrix.arch }}
@@ -209,7 +262,7 @@ jobs:

  windows:
    name: Build wheels on Windows
-    runs-on: windows-2019
+    runs-on: windows-2022
    # Don't run on OCIO forks
    if: |
      github.event_name != 'schedule' ||
@@ -235,6 +288,9 @@ jobs:
          - build: CPython 3.11 64 bits
            python: cp311-*
            arch: AMD64
+          - build: CPython 3.12 64 bits
+            python: cp312-*
+            arch: AMD64

    steps:
      - uses: actions/checkout@v3
@@ -245,7 +301,7 @@ jobs:
          python-version: '3.8'

      - name: Build wheels
-        uses: pypa/cibuildwheel@v2.13.1
+        uses: pypa/cibuildwheel@v2.16.2
        env:
          CIBW_BUILD: ${{ matrix.python }}
          CIBW_ARCHS: ${{ matrix.arch }}
@@ -3,8 +3,13 @@

 This file documents releases up to 1.1.1.  For a description of version 2.0 and later
 please refer to the Releases page on GitHub:
+
 https://github.com/AcademySoftwareFoundation/OpenColorIO/releases

+and for more details please see the release notes in latest documentation pages:
+
+https://opencolorio.readthedocs.io/en/latest/releases/_index.html#releases
+
 **Version 1.1.1 (April 2 2019):**
    * Added optional compatibility for building apps with OpenImageIO 1.9+
    * Added USE_SSE checks to fix Linux build failure
@@ -29,7 +29,7 @@ endif()
 # Project definition.

 project(OpenColorIO 
-    VERSION 2.3.0
+    VERSION 2.3.2
    DESCRIPTION "OpenColorIO (OCIO) is a complete color management solution"
    HOMEPAGE_URL https://github.com/AcademySoftwareFoundation/OpenColorIO
    LANGUAGES CXX C)
@@ -180,8 +180,11 @@ option(OCIO_USE_OIIO_FOR_APPS "Request OIIO to build apps (ociolutimage, ociocon


 if (NOT APPLE)
-    if ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(AMD64|IA64|EM64T|X86|x86_64|i386|i686)")
+    if ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(AMD64|IA64|EM64T|x86_64|X86|i386|i686)")
        # Intel-based architecture (not APPLE)
+        if ("${CMAKE_SYSTEM_PROCESSOR}" MATCHES "(X86|i386|i686)")
+            set(OCIO_ARCH_X86_32 1)
+        endif()
        set(OCIO_ARCH_X86 1)
        set(OCIO_BUILD_ENABLE_OPTIMIZATIONS_SSE ON)
        set(OCIO_BUILD_ENABLE_OPTIMIZATIONS_AVX ON)
@@ -243,7 +243,7 @@ expected to validate the behavior of every part of OCIO:
 * Any change to existing functionality should have tests added if they
  don't already exist.

-The test should should be run, via ``ctest``, before submitting a pull request.
+The test should be run, via ``ctest``, before submitting a pull request.

 ## Versioning Policy

@@ -38,7 +38,7 @@ Houdini, Silhouette FX, and
 [others](https://opencolorio.org/#supported_apps).

 OpenColorIO is free and open source software ([LICENSE](LICENSE)), and
-one of several projects actvively sponsored by the ASWF
+one of several projects actively sponsored by the ASWF
 ([Academy Software Foundation](https://www.aswf.io/)).

 OpenColorIO Project Mission
@@ -50,12 +50,12 @@ content creation applications and pipelines.

 OpenColorIO aims to:

-* be stable, secure, and thouroughly tested on Linux, macOS, and Windows
+* be stable, secure, and thoroughly tested on Linux, macOS, and Windows
 * be performant on modern CPUs and GPUs
 * be simple, scalable, and well documented
 * be compatible with critical color and imaging standards
 * provide lossless color processing wherever possible
-* maintain config backwards compatability across major versions
+* maintain config backwards compatibility across major versions
 * have every new feature carefully reviewed by leaders from the motion picture, 
  VFX, animation, and video game industries
 * have a healthy and active community
@@ -65,13 +65,14 @@ OpenColorIO Project Governance
 ------------------------------

 OpenColorIO is governed by the Academy Software Foundation (ASWF). See 
-[GOVERNANCE.md](GOVERNANCE.md) for detailed infomation about how the project 
+[GOVERNANCE.md](GOVERNANCE.md) for detailed information about how the project 
 operates.

 Web Resources
 -------------

 * Website: <http://opencolorio.org>
+* Documentation: <https://opencolorio.readthedocs.io/en/latest/>
 * Mailing lists:
  * Developer: <ocio-dev@lists.aswf.io>
  * User: <ocio-user@lists.aswf.io>
@@ -99,6 +100,11 @@ The following reference implementations are provided:
 * Other
  * nuke-default

+Sources for the newer builtin ACES configuration files can be found in the releases section of the
+[OpenColorIO-Config-ACES](https://github.com/AcademySoftwareFoundation/OpenColorIO-Config-ACES)
+repository.
+
+
 Acknowledgements
 ----------------

@@ -2456,6 +2456,10 @@ public:
     */
    bool hasChannelCrosstalk() const;

+    /**
+     * Returns a hash string generated by hashing the cachedIDs of the (unoptimized) list of ops
+     * contained in the Processor. (This forms part of the key used by the config's processor cache.)
+     */
    const char * getCacheID() const;

    /**
@@ -760,7 +760,7 @@ extern OCIOEXPORT const char * OCIO_INACTIVE_COLORSPACES_ENVVAR;
 * The envvar 'OCIO_OPTIMIZATION_FLAGS' provides a way to force a given optimization level.
 * Remove the variable or set the value to empty to not use it. Set the value of the variable
 * to the desired optimization level as either an integer or hexadecimal value.
- * Ex: OCIO_OPTIMIZATION_FLAGS="20479" or "0x4FFF" for OPTIMIZATION_LOSSLESS.
+ * Ex: OCIO_OPTIMIZATION_FLAGS="144457667" or "0x89c3fc3" for OPTIMIZATION_LOSSLESS.
 */
 extern OCIOEXPORT const char * OCIO_OPTIMIZATION_FLAGS_ENVVAR;

@@ -4,7 +4,10 @@ requires = [
    "wheel",
    "cmake>=3.13",
    "ninja; sys_platform != 'win32' and platform_machine != 'arm64'",
-    # Documentation requirements
+    # Documentation requirements (see docs/requirements.txt for details)
+    "urllib3<2",
+    "docutils>=0.18.1",
+    "sphinx<=7.1.2",
    "six",
    "testresources",
    "recommonmark",
@@ -23,10 +26,6 @@ test-command = [
    "ociocheck"
 ]

-manylinux-x86_64-image = "manylinux2014"
-manylinux-i686-image = "manylinux2014"
-manylinux-aarch64-image = "manylinux2014"
-
 [tool.cibuildwheel.linux]
 before-build = "share/ci/scripts/linux/yum/install_docs_env.sh"

@@ -34,4 +33,5 @@ before-build = "share/ci/scripts/linux/yum/install_docs_env.sh"
 before-build = "share/ci/scripts/macos/install_docs_env.sh"

 [tool.cibuildwheel.windows]
-before-build = "bash -c share/ci/scripts/windows/install_docs_env.sh"
+environment = { PATH="$GITHUB_WORKSPACE/doxygen;$PATH" }
+before-build = 'bash -c "share/ci/scripts/windows/install_docs_env.sh $GITHUB_WORKSPACE/doxygen"'
@@ -12,6 +12,7 @@ classifiers =
    Programming Language :: Python :: 3.9
    Programming Language :: Python :: 3.10
    Programming Language :: Python :: 3.11
+    Programming Language :: Python :: 3.12
    Programming Language :: Python :: Implementation :: CPython
    Programming Language :: C++
 description = OpenColorIO (OCIO) is a complete color management solution geared towards motion picture production with an emphasis on visual effects and computer animation.
@@ -5,6 +5,7 @@
 set -ex

 HERE=$(dirname $0)
+DOXYGEN_LOCATION="$1"

-bash $HERE/install_doxygen.sh latest
+bash $HERE/install_doxygen.sh "$DOXYGEN_LOCATION"
 pip install -r $HERE/../../../../docs/requirements.txt
@@ -4,10 +4,18 @@

 set -ex

-DOXYGEN_VERSION="$1"
+DOXYGEN_LOCATION="$1"

-if [ "$DOXYGEN_VERSION" == "latest" ]; then
-    choco install doxygen.install
-else
-    choco install doxygen.install --version=${DOXYGEN_VERSION}
-fi
+# Utility to parse JSON object.
+choco install jq
+
+# Get the URL of the latest zip package for Doxygen.
+url=$(curl -s 'https://api.github.com/repos/doxygen/doxygen/releases/latest' | jq -r '.assets[] | select(.name | test("doxygen-.*windows.x64.bin.zip")) | .browser_download_url')
+
+# Download the zip.
+mkdir $DOXYGEN_LOCATION
+cd $DOXYGEN_LOCATION
+powershell 'iwr -URI '$url' -OutFile doxygen.zip'
+
+# Unzip the file into $DOXYGEN_LOCATION.
+unzip -o doxygen.zip
@@ -216,7 +216,7 @@ macro (ocio_handle_dependency dep_name)
            endif()

            if(ocio_dep_REQUIRED)
-                if(NOT ${dep_name}_FOUND AND NOT ocio_dep_VERSION)
+                if(NOT ${dep_name}_FOUND)
                    message(SEND_ERROR "${ColorError}${dep_name} is required, will abort at the end.${ColorReset}")
                endif()
            endif()
@@ -8,6 +8,7 @@
 #   minizip-ng_LIBRARY      - minizip-ng library to link to
 #   minizip-ng_INCLUDE_DIR  - Where to find mz.h and other headers
 #   minizip-ng_VERSION      - The version of the library
+#   minizip-ng_COMPAT       - Whether minizip-ng MZ_COMPAT was used or not
 #
 # Global targets defined by this module:
 #   MINIZIP::minizip-ng - IMPORTED target, if found
@@ -114,7 +115,9 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
            PATH_SUFFIXES
                include
                include/minizip-ng
+                include/minizip
                minizip-ng/include
+                minizip/include
        )

        # Minizip-ng uses prefix "lib" on all platform by default.
@@ -202,4 +205,16 @@ if(_minizip-ng_TARGET_CREATE)
    mark_as_advanced(minizip-ng_INCLUDE_DIR minizip-ng_LIBRARY minizip-ng_VERSION)

    target_link_libraries(MINIZIP::minizip-ng INTERFACE ZLIB::ZLIB)
-endif()
+endif()
+
+###############################################################################
+### Detect compatibility mode ###
+
+set(minizip-ng_COMPAT FALSE)
+if(minizip-ng_INCLUDE_DIR)
+    list(GET minizip-ng_INCLUDE_DIR 0 _minizip-ng_INCLUDE_DIR)
+    if(EXISTS "${_minizip-ng_INCLUDE_DIR}/mz_compat.h")
+        set(minizip-ng_COMPAT TRUE)
+    endif()
+endif()
+mark_as_advanced(minizip-ng_COMPAT)
@@ -28,11 +28,12 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
    # Find include directory
    find_path(pystring_INCLUDE_DIR
        NAMES
-            pystring/pystring.h
+            pystring.h
        HINTS
            ${pystring_ROOT}
        PATH_SUFFIXES
            include
+            include/pystring
            pystring/include
    )

@@ -10,10 +10,9 @@
 #   yaml-cpp_VERSION        - Library's version
 #
 # Global targets defined by this module:
-#   yaml-cpp
+#   yaml-cpp::yaml-cpp
 #
 # For compatibility with the upstream CMake package, the following variables and targets are defined:
-#   yaml-cpp::yaml-cpp      - Alias of the yaml-cpp target
 #   YAML_CPP_LIBRARIES      - Libraries to link against yaml-cpp
 #   YAML_CPP_INCLUDE_DIR    - Include directory
 #
@@ -41,16 +40,26 @@ if(CMAKE_BUILD_TYPE MATCHES "[Dd][Ee][Bb][Uu][Gg]")
   set(BUILD_TYPE_DEBUG ON)
 endif()

+if(yaml-cpp_FIND_QUIETLY)
+    set(quiet QUIET)
+endif()
+
 if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
    set(_yaml-cpp_REQUIRED_VARS yaml-cpp_LIBRARY)

+    # Search for yaml-cpp-config.cmake
    if(NOT DEFINED yaml-cpp_ROOT)
-        # Search for yaml-cpp-config.cmake
-        find_package(yaml-cpp ${yaml-cpp_FIND_VERSION} CONFIG QUIET)
+        find_package(yaml-cpp ${yaml-cpp_FIND_VERSION} CONFIG ${quiet})
    endif()

    if(yaml-cpp_FOUND)
-        get_target_property(yaml-cpp_LIBRARY yaml-cpp LOCATION)
+        # Alias target for yaml-cpp < 0.8 compatibility
+        if(TARGET yaml-cpp AND NOT TARGET yaml-cpp::yaml-cpp)
+            add_library(yaml-cpp::yaml-cpp ALIAS yaml-cpp)
+        endif()
+
+        get_target_property(yaml-cpp_INCLUDE_DIR yaml-cpp::yaml-cpp INTERFACE_INCLUDE_DIRECTORIES)
+        get_target_property(yaml-cpp_LIBRARY yaml-cpp::yaml-cpp LOCATION)
    else()

        # As yaml-cpp-config.cmake search fails, search an installed library
@@ -59,14 +68,14 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
        list(APPEND _yaml-cpp_REQUIRED_VARS yaml-cpp_INCLUDE_DIR yaml-cpp_VERSION)

        # Search for yaml-cpp.pc
-        find_package(PkgConfig QUIET)
-        pkg_check_modules(PC_yaml-cpp QUIET "yaml-cpp>=${yaml-cpp_FIND_VERSION}")
+        find_package(PkgConfig ${quiet})
+        pkg_check_modules(PC_yaml-cpp ${quiet} "yaml-cpp>=${yaml-cpp_FIND_VERSION}")

        # Try to detect the version installed, if any.
        if(NOT PC_yaml-cpp_FOUND)
-            pkg_search_module(PC_yaml-cpp QUIET "yaml-cpp")
+            pkg_search_module(PC_yaml-cpp ${quiet} "yaml-cpp")
        endif()
-        
+
        # Find include directory
        find_path(yaml-cpp_INCLUDE_DIR 
            NAMES
@@ -91,7 +100,7 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)
            # Prefer static lib names
            set(_yaml-cpp_STATIC_LIB_NAMES 
                "${CMAKE_STATIC_LIBRARY_PREFIX}yaml-cpp${CMAKE_STATIC_LIBRARY_SUFFIX}")
-            
+
            # Starting from 0.7.0, all platforms uses the suffix "d" for debug.
            # See https://github.com/jbeder/yaml-cpp/blob/master/CMakeLists.txt#L141
            if(BUILD_TYPE_DEBUG)
@@ -127,42 +136,37 @@ if(NOT OCIO_INSTALL_EXT_PACKAGES STREQUAL ALL)

    include(FindPackageHandleStandardArgs)
    find_package_handle_standard_args(yaml-cpp
-        REQUIRED_VARS 
+        REQUIRED_VARS
            ${_yaml-cpp_REQUIRED_VARS}
        VERSION_VAR
            yaml-cpp_VERSION
    )
-endif()
-
-###############################################################################
-### Create target
-
-if(yaml-cpp_FOUND AND NOT TARGET yaml-cpp)
-    add_library(yaml-cpp UNKNOWN IMPORTED GLOBAL)
-    set(_yaml-cpp_TARGET_CREATE TRUE)
-endif()
-
-###############################################################################
-### Configure target ###
-
-if(_yaml-cpp_TARGET_CREATE)
-    set_target_properties(yaml-cpp PROPERTIES
-        IMPORTED_LOCATION ${yaml-cpp_LIBRARY}
-        INTERFACE_INCLUDE_DIRECTORIES ${yaml-cpp_INCLUDE_DIR}
-    )

    mark_as_advanced(yaml-cpp_INCLUDE_DIR yaml-cpp_LIBRARY yaml-cpp_VERSION)
 endif()

 ###############################################################################
-### Set variables for compatibility ###
+### Create target

-if(TARGET yaml-cpp AND NOT TARGET yaml-cpp::yaml-cpp)
-    add_library(yaml-cpp::yaml-cpp ALIAS yaml-cpp)
-endif()
+if (yaml-cpp_FOUND AND NOT TARGET yaml-cpp::yaml-cpp)
+    add_library(yaml-cpp::yaml-cpp UNKNOWN IMPORTED GLOBAL)
+    set_target_properties(yaml-cpp::yaml-cpp PROPERTIES
+        IMPORTED_LOCATION ${yaml-cpp_LIBRARY}
+        INTERFACE_INCLUDE_DIRECTORIES ${yaml-cpp_INCLUDE_DIR}
+    )

-if(yaml-cpp_INCLUDE_DIR)
-    set(YAML_CPP_INCLUDE_DIR "${yaml-cpp_INCLUDE_DIR}")
-endif()
+    # Required because Installyaml-cpp.cmake creates `yaml-cpp::yaml-cpp`
+    # as an alias, and aliases get resolved in exported targets, causing the
+    # find_dependency(yaml-cpp) call in OpenColorIOConfig.cmake to fail.
+    # This can be removed once Installyaml-cpp.cmake targets yaml-cpp 0.8.
+    if (NOT TARGET yaml-cpp)
+        add_library(yaml-cpp ALIAS yaml-cpp::yaml-cpp)
+    endif ()
+endif ()

-set(YAML_CPP_LIBRARIES yaml-cpp::yaml-cpp)
+if (yaml-cpp_FOUND)
+    # TODO: Remove this variable and use the `yaml-cpp::yaml-cpp` target
+    # directly when the minimum version of yaml-cpp is updated to 0.8.
+    get_target_property(YAML_CPP_INCLUDE_DIR yaml-cpp::yaml-cpp INCLUDE_DIRECTORIES)
+    set(YAML_CPP_LIBRARIES yaml-cpp::yaml-cpp)
+endif ()
@@ -110,7 +110,7 @@ if(NOT OpenEXR_FOUND AND OCIO_INSTALL_EXT_PACKAGES AND NOT OCIO_INSTALL_EXT_PACK
            -DBUILD_SHARED_LIBS=OFF
            -DBUILD_TESTING=OFF
            -DOPENEXR_INSTALL_EXAMPLES=OFF
-            -DOPENEXR_INSTALL_TOOLS=OFF
+            -DOPENEXR_BUILD_TOOLS=OFF
            # Try to use in-source built Imath first, if available.
            -DCMAKE_PREFIX_PATH=${_EXT_DIST_ROOT}
        )
@@ -38,7 +38,7 @@ if(NOT pystring_FOUND AND OCIO_INSTALL_EXT_PACKAGES AND NOT OCIO_INSTALL_EXT_PAC
    else()
        set(pystring_VERSION ${pystring_FIND_VERSION})
    endif()
-    set(pystring_INCLUDE_DIR "${_EXT_DIST_ROOT}/${CMAKE_INSTALL_INCLUDEDIR}")
+    set(pystring_INCLUDE_DIR "${_EXT_DIST_ROOT}/${CMAKE_INSTALL_INCLUDEDIR}/pystring")

    set(pystring_LIBRARY 
        "${_EXT_DIST_ROOT}/${CMAKE_INSTALL_LIBDIR}/${CMAKE_STATIC_LIBRARY_PREFIX}pystring${CMAKE_STATIC_LIBRARY_SUFFIX}")
@@ -21,8 +21,8 @@
 ###############################################################################
 ### Create target (if previous 'find_package' call hasn't) ###

-if(NOT TARGET yaml-cpp)
-    add_library(yaml-cpp UNKNOWN IMPORTED GLOBAL)
+if(NOT TARGET yaml-cpp::yaml-cpp)
+    add_library(yaml-cpp::yaml-cpp UNKNOWN IMPORTED GLOBAL)
    set(_yaml-cpp_TARGET_CREATE TRUE)
 endif()

@@ -138,7 +138,7 @@ if(NOT yaml-cpp_FOUND AND OCIO_INSTALL_EXT_PACKAGES AND NOT OCIO_INSTALL_EXT_PAC
                                 --parallel
        )

-        add_dependencies(yaml-cpp yaml-cpp_install)
+        add_dependencies(yaml-cpp::yaml-cpp yaml-cpp_install)
        if(OCIO_VERBOSE)
            message(STATUS "Installing yaml-cpp: ${yaml-cpp_LIBRARY} (version \"${yaml-cpp_VERSION}\")")
        endif()
@@ -149,7 +149,7 @@ endif()
 ### Configure target ###

 if(_yaml-cpp_TARGET_CREATE)
-    set_target_properties(yaml-cpp PROPERTIES
+    set_target_properties(yaml-cpp::yaml-cpp PROPERTIES
        IMPORTED_LOCATION ${yaml-cpp_LIBRARY}
        INTERFACE_INCLUDE_DIRECTORIES ${yaml-cpp_INCLUDE_DIR}
    )
@@ -157,15 +157,5 @@ if(_yaml-cpp_TARGET_CREATE)
    mark_as_advanced(yaml-cpp_INCLUDE_DIR yaml-cpp_LIBRARY yaml-cpp_VERSION)
 endif()

-###############################################################################
-### Set variables for compatibility ###
-
-if(TARGET yaml-cpp AND NOT TARGET yaml-cpp::yaml-cpp)
-    add_library(yaml-cpp::yaml-cpp ALIAS yaml-cpp)
-endif()
-
-if(yaml-cpp_INCLUDE_DIR)
-    set(YAML_CPP_INCLUDE_DIR "${yaml-cpp_INCLUDE_DIR}")
-endif()
-
+set(YAML_CPP_INCLUDE_DIR "${yaml-cpp_INCLUDE_DIR}")
 set(YAML_CPP_LIBRARIES yaml-cpp::yaml-cpp)
@@ -59,7 +59,7 @@ else()
    message(STATUS "Performing Test COMPILER_SUPPORTS_SSE2 - Failed")
 endif()

-set(CMAKE_REQUIRED_FLAGS "${_cmake_cxx_flags_orig}")
+set(CMAKE_CXX_FLAGS "${_cmake_cxx_flags_orig}")
 unset(_cmake_cxx_flags_orig)

 if(__universal_build)
@@ -13,7 +13,7 @@ endif()

 # MSVC doesn't have flags
 if(USE_GCC OR USE_CLANG)
-    set(CMAKE_CXX_FLAGS "-w -msse3")
+    set(CMAKE_CXX_FLAGS "-w -mssse3")
 endif()

 if (APPLE AND __universal_build)
@@ -107,8 +107,8 @@ if(USE_GCC OR USE_CLANG)
    endif()

    if(OCIO_ENABLE_SANITIZER)
-        set(PLATFORM_COMPILE_OPTIONS "${PLATFORM_COMPILE_OPTIONS};-fno-omit-frame-pointer;-fsanitize=address")
-        set(PLATFORM_LINK_OPTIONS "${PLATFORM_LINK_OPTIONS};-fsanitize=address")
+        set(PLATFORM_COMPILE_OPTIONS "${PLATFORM_COMPILE_OPTIONS};-fno-omit-frame-pointer;-fsanitize=address;-fsanitize=undefined")
+        set(PLATFORM_LINK_OPTIONS "${PLATFORM_LINK_OPTIONS};-fsanitize=address;-fsanitize=undefined")
    endif()

 endif()
@@ -9,7 +9,6 @@
 #if OCIO_USE_AVX

 #include <immintrin.h>
-#include <stdio.h>

 #include <OpenColorIO/OpenColorIO.h>
 #include "BitDepthUtils.h"
@@ -9,7 +9,6 @@
 #if OCIO_USE_AVX2

 #include <immintrin.h>
-#include <stdio.h>

 #include <OpenColorIO/OpenColorIO.h>
 #include "BitDepthUtils.h"
@@ -389,7 +389,7 @@ elseif(APPLE)


    # Check for minizip first since our Findminizip module sets minizip-ng_LIBRARY.
-    if (minizip_LIBRARY)
+    if (minizip_LIBRARY OR minizip-ng_COMPAT)
        get_filename_component(_minizip-ng_LIBDIR "${minizip_LIBRARY}" DIRECTORY)
        set(_minizip-ng_NAME "minizip")
    elseif(minizip-ng_LIBRARY)
@@ -50,6 +50,13 @@ static inline void cpuid(int index, int *data)
 {
 #if _MSC_VER
    __cpuid(data, index);
+#elif OCIO_ARCH_X86_32
+    __asm__ volatile (
+        "mov    %%ebx, %%esi \n\t"
+        "cpuid               \n\t"
+        "xchg   %%ebx, %%esi"
+        : "=a" (data[0]), "=S" (data[1]), "=c" (data[2]), "=d" (data[3])
+        : "0" (index), "2"(0));
 #else
    __asm__ volatile (
        "mov    %%rbx, %%rsi \n\t"
@@ -100,10 +107,10 @@ CPUInfo::CPUInfo()
            flags |= X86_CPU_FLAG_SSE42;

        /* Check OSXSAVE and AVX bits */
-        if (info.reg.ecx & 0x18000000)
+        if ((info.reg.ecx & 0x18000000) == 0x18000000)
        {
            xcr = xgetbv();
-            if(xcr & 0x6) {
+            if((xcr & 0x6) == 0x6) {
                flags |= X86_CPU_FLAG_AVX;

                if(info.reg.ecx & 0x20000000) {
@@ -122,7 +129,7 @@ CPUInfo::CPUInfo()

        /* OPMASK/ZMM state */
        if ((xcr & 0xe0) == 0xe0) {
-            if ((flags & X86_CPU_FLAG_AVX2) && (info.reg.ebx & 0xd0030000))
+            if ((flags & X86_CPU_FLAG_AVX2) && ((info.reg.ebx & 0xd0030000) == 0xd0030000))
                flags |= X86_CPU_FLAG_AVX512;
        }
    }
@@ -3,10 +3,13 @@


 #cmakedefine01 OCIO_ARCH_X86
+#cmakedefine01 OCIO_ARCH_X86_32

 // Relevant only for arm64 architecture.
 #if defined(__aarch64__)
    #cmakedefine01 OCIO_USE_SSE2NEON
+#else
+    #define OCIO_USE_SSE2NEON 0
 #endif

 // On the Apple platform, a universal build is created for both x86_64 and arm64 architectures. 
@@ -12,6 +12,8 @@
 #include <regex>
 #include <functional>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "builtinconfigs/BuiltinConfigRegistry.h"
@@ -34,7 +36,6 @@
 #include "Platform.h"
 #include "PrivateTypes.h"
 #include "Processor.h"
-#include "pystring/pystring.h"
 #include "transforms/FileTransform.h"
 #include "utils/StringUtils.h"
 #include "ViewingRules.h"
@@ -435,7 +436,7 @@ public:
            {
                m_viewTransforms.push_back(vt->createEditableCopy());
            }
-
+            m_defaultViewTransform = rhs.m_defaultViewTransform;
            m_defaultLumaCoefs = rhs.m_defaultLumaCoefs;
            m_strictParsing = rhs.m_strictParsing;

@@ -2821,6 +2822,23 @@ bool Config::isColorSpaceLinear(const char * colorSpace, ReferenceSpaceType refe
        auto procToReference = config.getImpl()->getProcessorWithoutCaching(
            config, t, TRANSFORM_DIR_FORWARD
        );
+
+        // TODO: It could be useful to try and avoid evaluating points through ops that are
+        // expensive but highly unlikely to be linear (with inverse Lut3D being the prime example).
+        // There are some heuristics that are used in ConfigUtils.cpp that are intended to filter
+        // out color spaces from consideration before a processor is even calculated.  However,
+        // those are not entirely appropriate here since one could imagine wanting to know if a
+        // color space involving a FileTransform (an ASC CDL being a good example) is linear.
+        // Likewise, one might want to know whether a color space involving a Look or ColorSpace
+        // Transform is linear (both of those are filtered out by the ConfigUtils heuristics).
+        // It seems like the right approach here is to go ahead and build the processor and
+        // thereby convert File/Look/ColorSpace Transforms into ops.  But currently there is
+        // no method on the Processor class to know if it contains a Lut3D.  There is the
+        // ProcessorMetadata files list, though that is not as precise.  For example, it would
+        // not say if a CLF or CTF file contains a Lut3D or just a matrix.  Probably the best
+        // solution would be to have each op sub-class provide an isLinear method and then
+        // surface that on the Processor class, iterating over each op in the Processor.
+
        auto optCPUProc = procToReference->getOptimizedCPUProcessor(OPTIMIZATION_NONE);
        optCPUProc->apply(desc, descDst);

@@ -4100,6 +4118,10 @@ void Config::addLook(const ConstLookRcPtr & look)
        if(StringUtils::Lower(getImpl()->m_looksList[i]->getName()) == namelower)
        {
            getImpl()->m_looksList[i] = look->createEditableCopy();
+
+            AutoMutex lock(getImpl()->m_cacheidMutex);
+            getImpl()->resetCacheIDs();
+
            return;
        }
    }
@@ -4715,20 +4737,29 @@ ConstProcessorRcPtr Config::GetProcessorFromConfigs(const ConstContextRcPtr & sr
            "the source color space.");
    }

+    const char* csName = dstConfig->getDisplayViewColorSpaceName(dstDisplay, dstView);
+    const char* displayColorSpaceName = View::UseDisplayName(csName) ? dstDisplay : csName;
+    ConstColorSpaceRcPtr displayColorSpace = dstConfig->getColorSpace(displayColorSpaceName);
+    if (!displayColorSpace)
+    {
+        throw Exception("Can't create the processor for the destination config: "
+            "display color space not found.");
+    }
+
    auto p2 = dstConfig->getProcessor(dstContext, dstInterchangeName, dstDisplay, dstView, direction);
    if (!p2)
    {
        throw Exception("Can't create the processor for the destination config "
-            "and the destination color space.");
+            "and the destination display view transform.");
    }

    ProcessorRcPtr processor = Processor::Create();
    processor->getImpl()->setProcessorCacheFlags(srcConfig->getImpl()->m_cacheFlags);

-    // If the source color spaces is a data space, its corresponding processor
+    // If either of the color spaces are data spaces, its corresponding processor
    // will be empty, but need to make sure the entire result is also empty to
    // better match the semantics of how data spaces are handled.
-    if (!srcColorSpace->isData())
+    if (!srcColorSpace->isData() && !displayColorSpace->isData())
    {
        if (direction == TRANSFORM_DIR_INVERSE)
        {
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: BSD-3-Clause
 // Copyright Contributors to the OpenColorIO Project.

+#include <pystring.h>
+
 #include "ConfigUtils.h"
 #include "MathUtils.h"
 #include "utils/StringUtils.h"
@@ -165,7 +167,7 @@ bool GetInterchangeRolesForColorSpaceConversion(const char ** srcInterchangeCSNa

 // Return true if the color space name or its aliases contains sRGB (case-insensitive).
 //
-bool containsSRGB(ConstColorSpaceRcPtr & cs)
+bool containsSRGB(const ConstColorSpaceRcPtr & cs)
 {
    std::string name = StringUtils::Lower(cs->getName());
    if (StringUtils::Find(name, "srgb") != std::string::npos)
@@ -223,10 +225,31 @@ const char * getRefSpaceName(const ConstConfigRcPtr & cfg)
    return "";
 }

+// Find the first scene-referred color space with isdata: true.
+//
+const char * getDataSpaceName(const ConstConfigRcPtr & cfg)
+{
+    int nbCs = cfg->getNumColorSpaces(SEARCH_REFERENCE_SPACE_SCENE, COLORSPACE_ALL);
+
+    for (int i = 0; i < nbCs; i++)
+    {
+        const char * csname = cfg->getColorSpaceNameByIndex(SEARCH_REFERENCE_SPACE_SCENE, 
+                                                            COLORSPACE_ALL, 
+                                                            i);
+        ConstColorSpaceRcPtr cs = cfg->getColorSpace(csname);
+
+        if (cs->isData())
+        {
+            return csname;
+        }
+    }
+    return "";
+}
+
 // Return false if the supplied Processor modifies any of the supplied float values
 // by more than the supplied absolute tolerance amount.
 //
-bool isIdentityTransform(ConstProcessorRcPtr proc, 
+bool isIdentityTransform(const ConstProcessorRcPtr & proc, 
                         std::vector<float> & RGBAvals, 
                         float absTolerance)
 {
@@ -249,28 +272,143 @@ bool isIdentityTransform(ConstProcessorRcPtr proc,
    return true;
 }

-// Helper to avoid color spaces that are without transforms or are data spaces.
+// Determine whether a Processor contains a MatrixTransform with off-diagonal coefficients.
 //
-bool hasNoTransform(const ConstColorSpaceRcPtr & cs)
+bool hasNonTrivialMatrixTransform(const ConstProcessorRcPtr & proc)
+{
+    GroupTransformRcPtr gt = proc->createGroupTransform();
+    // The result of createGroupTransform only contains transforms that correspond to ops,
+    // in other words, there are no complex transforms such as File, Builtin, or ColorSpace,
+    // and the only GroupTransform is the enclosing one.
+    for (int i = 0; i < gt->getNumTransforms(); ++i)
+    {
+        ConstTransformRcPtr transform = gt->getTransform(i);
+        if (transform->getTransformType() == TRANSFORM_TYPE_MATRIX)
+        {
+            // Check that there is a significant off-diagonal coefficient in the matrix.
+            // This is to avoid matrices that are not actual color primary conversions,
+            // for example, the scale and offset that are sometimes prepended to a Lut1D.
+            ConstMatrixTransformRcPtr mtx = DynamicPtrCast<const MatrixTransform>(transform);
+            double values[16];
+            mtx->getMatrix(values);
+            for (int j = 0; j < 3 ; ++j)      // only checking rgb, not alpha
+            {
+                for (int k = 0; k < 3 ; ++k)  // only checking rgb, not alpha
+                {
+                    if (j != k)
+                    {
+                        if (std::abs(values[j * 4 + k]) > 0.1)
+                        {
+                            return true;
+                        }
+                    }
+                }
+            }
+        }
+    }
+    return false;
+}
+
+// Determine if the transform contains a type that is inappropriate for the heuristics.
+//
+bool containsBlockedTransform(const ConstTransformRcPtr & transform)
+{
+    // If it's a GroupTransform, need to recurse into it to check the contents.
+    if (transform->getTransformType() == TRANSFORM_TYPE_GROUP)
+    {
+        ConstGroupTransformRcPtr gt = DynamicPtrCast<const GroupTransform>(transform);
+        for (int i = 0; i < gt->getNumTransforms(); ++i)
+        {
+            ConstTransformRcPtr tr = gt->getTransform(i);
+            if (containsBlockedTransform(tr))
+            {
+                return true;
+            }
+        }
+    }
+
+    // Prevent FileTransforms from being used, except for spi1d and spimtx since these
+    // may be used with OCIO v1 configs to implement the type of color spaces the heuristics
+    // are designed to look for.  (E.g. The sRGB Texture space in the legacy ACES configs.)
+    else if (transform->getTransformType() == TRANSFORM_TYPE_FILE)
+    {
+        ConstFileTransformRcPtr ft = DynamicPtrCast<const FileTransform>(transform);
+        std::string filepath = ft->getSrc();
+        std::string root, extension;
+        pystring::os::path::splitext(root, extension, filepath);
+        extension = StringUtils::Lower(extension);
+        if (extension != ".spi1d" && extension != ".spimtx")
+        {
+            return true;
+        }
+    }
+
+    // Prevent transforms that may be hiding a FileTransform.
+    else if (transform->getTransformType() == TRANSFORM_TYPE_COLORSPACE
+     || transform->getTransformType() == TRANSFORM_TYPE_DISPLAY_VIEW
+     || transform->getTransformType() == TRANSFORM_TYPE_LOOK)
+    {
+        return true;
+    }
+
+    // Putting this here since Lut3D is the main type of transform to avoid,
+    // however given that the input transform comes directly from a color space
+    // and has not been converted to a processor yet, it should never actually
+    // have a transform of this type (it would still be a FileTransform).
+    else if (transform->getTransformType() == TRANSFORM_TYPE_LUT3D)
+    {
+        return true;
+    }
+    return false;
+}
+
+// Look at the to_ref/from_ref transforms in the color space and exclude color spaces
+// that are probably not what the heuristics are looking for and could be prohibitively
+// expensive to fully check.
+//
+// Because this check is done before a processor is built, it is inexpensive but it may
+// be inaccurate.  In other words, it's possible that this check will exclude some 
+// reasonable color spaces, but that's better than trying to invert 3d-LUTs, etc.
+//
+// cs -- Color space object to check.
+// refSpaceType -- Exclude if the color space is not of the same reference space type.
+// blockRefSpaces -- Exclude the color space if it does not have any transforms.
+//
+bool excludeColorSpaceFromHeuristics(const ConstColorSpaceRcPtr & cs, 
+                                     ReferenceSpaceType refSpaceType,
+                                     bool blockRefSpaces)
 {
    if (cs->isData())
    {
        return true;
    }
-    ConstTransformRcPtr srcTransform = cs->getTransform(COLORSPACE_DIR_TO_REFERENCE);
-    if (!srcTransform)
+
+    if (cs->getReferenceSpaceType() != refSpaceType)
    {
-        srcTransform = cs->getTransform(COLORSPACE_DIR_FROM_REFERENCE);
-        if (srcTransform)
-        {
-            return false;
-        }
-        else
-        {
-            return true;
-        }
+        return true;
+    }
+
+    ConstTransformRcPtr transform = cs->getTransform(COLORSPACE_DIR_TO_REFERENCE);
+    if (transform)
+    {
+        // The to_ref transform is what the heuristics try to use first, so if that
+        // does not contain problematic transforms, it's ok to proceed without checking
+        // the from_ref transform.
+
+        return containsBlockedTransform(transform);
+    }
+
+    // There is no to_ref transform, check if the from_ref is present.
+    transform = cs->getTransform(COLORSPACE_DIR_FROM_REFERENCE);
+    if (transform)
+    {
+        return containsBlockedTransform(transform);
+    }
+    // Color space contains no transforms (it's a reference space).
+    else
+    {
+        return blockRefSpaces;
    }
-    return false;
 }

 // Test the supplied color space against a set of color spaces in the built-in config.
@@ -288,17 +426,6 @@ int getReferenceSpaceFromLinearSpace(const ConstConfigRcPtr & srcConfig,
                                     const ConstColorSpaceRcPtr & cs,
                                     const ConstConfigRcPtr & builtinConfig)
 {
-    // Currently only handling scene-referred spaces in the heuristics.
-    if (cs->getReferenceSpaceType() == REFERENCE_SPACE_DISPLAY)
-    {
-        return -1;
-    }
-    // Don't check spaces without transforms / data spaces.
-    if (hasNoTransform(cs))
-    {
-        return -1;
-    }
-
    // Define a set of (somewhat arbitrary) RGB values to test whether the combined transform is 
    // enough of an identity.
    std::vector<float> vals = { 0.7f,  0.4f,  0.02f, 0.f,
@@ -353,14 +480,9 @@ int getReferenceSpaceFromLinearSpace(const ConstConfigRcPtr & srcConfig,
 //
 int getReferenceSpaceFromSRGBSpace(const ConstConfigRcPtr & srcConfig, 
                                   const char * srcRefName,
-                                   const ConstColorSpaceRcPtr cs,
+                                   const ConstColorSpaceRcPtr & cs,
                                   const ConstConfigRcPtr & builtinConfig)
 {
-    // Currently only handling scene-referred spaces in the heuristics.
-    if (cs->getReferenceSpaceType() == REFERENCE_SPACE_DISPLAY)
-    {
-        return -1;
-    }
    // Get a transform in the to-reference direction.
    ConstTransformRcPtr toRefTransform;
    ConstTransformRcPtr ctransform = cs->getTransform(COLORSPACE_DIR_TO_REFERENCE);
@@ -405,6 +527,18 @@ int getReferenceSpaceFromSRGBSpace(const ConstConfigRcPtr & srcConfig,

    ConstProcessorRcPtr proc = srcConfig->getProcessor(toRefTransform, TRANSFORM_DIR_FORWARD);

+    // Ensure that the color space is not only an sRGB curve, it needs to have a color matrix
+    // too or else the last step below could succeed by pairing the built-in sRGB space with
+    // a linear space that cancels out the matrix in the built-in sRGB space.
+        // NB: This is being done after the getProcessor call rather than simply looking at
+        // the raw color space transform contents since once it becomes a processor, the complex
+        // transforms (e.g. File, ColorSpace, Builtins) that could be hiding a matrix are 
+        // converted into ops.
+    if (!hasNonTrivialMatrixTransform(proc))
+    {
+        return -1;
+    }
+
    ConstCPUProcessorRcPtr cpu  = proc->getOptimizedCPUProcessor(OPTIMIZATION_NONE);
    // Convert the non-linear values to linear.
    cpu->apply(desc, descDst);
@@ -422,6 +556,7 @@ int getReferenceSpaceFromSRGBSpace(const ConstConfigRcPtr & srcConfig,
            out[i] = 1.055f * std::pow(out[i], 1.f / 2.4f) - 0.055f;
        }
        // Compare against the original source values.
+        // (This assumes equal channel sRGB values remain so in the reference space of src config.)
        if (!EqualWithAbsError(vals[i], out[i], 1e-3f))
        {
            return -1;
@@ -442,6 +577,8 @@ int getReferenceSpaceFromSRGBSpace(const ConstConfigRcPtr & srcConfig,
    // sRGB texture space. If the result is an identity, then that tells what the source config
    // reference space is.

+    // At this point, cs has the expected non-linearity and a non-trivial matrix to its reference space.
+    // Now try to identify the matrix.
    for (int i = 0; i < getNumberOfbuiltinLinearSpaces(); i++)
    {
        ConstProcessorRcPtr proc = Config::GetProcessorFromConfigs(srcConfig,
@@ -511,7 +648,7 @@ void IdentifyInterchangeSpace(const char ** srcInterchange,

    // Identify the name of a reference space in the source config.
    *srcInterchange = getRefSpaceName(srcConfig);
-    if (!*srcInterchange)
+    if (!**srcInterchange)
    {
        std::ostringstream os;
        os  << "The supplied config does not have a color space for the reference.";
@@ -531,8 +668,16 @@ void IdentifyInterchangeSpace(const char ** srcInterchange,
    for (int i = 0; i < nbCs; i++)
    {
        ConstColorSpaceRcPtr cs = srcConfig->getColorSpace(srcConfig->getColorSpaceNameByIndex(i));
+
        if (containsSRGB(cs))
        {
+            // Exclude color spaces that may be too expensive to test or otherwise inappropriate.
+            // Currently only handling scene-referred spaces in the heuristics.
+            if (excludeColorSpaceFromHeuristics(cs, REFERENCE_SPACE_SCENE, true))
+            {
+                continue;
+            }
+
            refColorSpacePrimsIndex = getReferenceSpaceFromSRGBSpace(srcConfig, 
                                                                     *srcInterchange,
                                                                     cs, 
@@ -549,6 +694,14 @@ void IdentifyInterchangeSpace(const char ** srcInterchange,
        for (int i = 0; i < nbCs; i++)
        {
            ConstColorSpaceRcPtr cs = srcConfig->getColorSpace(srcConfig->getColorSpaceNameByIndex(i));
+
+            // Exclude color spaces that may be too expensive to test or otherwise inappropriate.
+            // Currently only handling scene-referred spaces in the heuristics.
+            if (excludeColorSpaceFromHeuristics(cs, REFERENCE_SPACE_SCENE, true))
+            {
+                continue;
+            }
+
            if (srcConfig->isColorSpaceLinear(cs->getName(), REFERENCE_SPACE_SCENE))
            {
                refColorSpacePrimsIndex = getReferenceSpaceFromLinearSpace(srcConfig,
@@ -602,6 +755,18 @@ const char * IdentifyBuiltinColorSpace(const ConstConfigRcPtr & srcConfig,
        throw Exception(os.str().c_str());
    }

+    if (builtinColorSpace->isData())
+    {
+        const char * dataName = getDataSpaceName(srcConfig);
+        if (!*dataName)
+        {
+            std::ostringstream os;
+            os  << "The requested space is a data space but the supplied config does not have a data space.";
+            throw Exception(os.str().c_str());
+        }
+        return dataName;
+    }
+
    ReferenceSpaceType builtinRefSpaceType = builtinColorSpace->getReferenceSpaceType();

    // Identify interchange spaces.  Passing an empty string for the source color space
@@ -633,8 +798,8 @@ const char * IdentifyBuiltinColorSpace(const ConstConfigRcPtr & srcConfig,
                                    0.f,   0.f,   0.f,   0.f,
                                    1.f,   1.f,   1.f,   0.f };

-        // Loop over each non-data color space in the source config and test if the conversion to
-        // the specified space in the built-in config is an identity.
+        // Loop over the active, non-excluded, color spaces in the source config and test if the
+        // conversion to the specified space in the built-in config is an identity.
        //
        //    Note that there is a possibility that both the source and built-in sides of the
        //    transform could be an identity (e.g., if the user asks for ACES2065-1 and that is
@@ -646,7 +811,8 @@ const char * IdentifyBuiltinColorSpace(const ConstConfigRcPtr & srcConfig,
        for (int i = 0; i < nbCs; i++)
        {
            ConstColorSpaceRcPtr cs = srcConfig->getColorSpace(srcConfig->getColorSpaceNameByIndex(i));
-            if (cs->isData() || (cs->getReferenceSpaceType() != builtinRefSpaceType))
+
+            if (excludeColorSpaceFromHeuristics(cs, builtinRefSpaceType, false))
            {
                continue;
            }
@@ -7,6 +7,8 @@
 #include <sstream>
 #include <string>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "ContextVariableUtils.h"
@@ -15,7 +17,6 @@
 #include "OCIOZArchive.h"
 #include "PathUtils.h"
 #include "PrivateTypes.h"
-#include "pystring/pystring.h"
 #include "utils/StringUtils.h"

 namespace OCIO_NAMESPACE
@@ -4,6 +4,8 @@
 #include <cstring>
 #include <unordered_set>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "Display.h"
@@ -19,7 +21,6 @@
 #include "ParseUtils.h"
 #include "PathUtils.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "utils/StringUtils.h"
 #include "ViewingRules.h"
 #include "yaml-cpp/yaml.h"
@@ -4737,9 +4738,9 @@ inline void save(YAML::Emitter & out, const Config & config)
    out << YAML::Newline;
    out << YAML::Newline;

-    if (configMajorVersion >= 2)
+    if (configMajorVersion >= 2 || config.getNumEnvironmentVars() > 0)
    {
-        // Print the environment even if empty.
+        // For v2 configs, write the environment section, even if empty.
        out << YAML::Key << "environment";
        out << YAML::Value << YAML::BeginMap;
        for(int i = 0; i < config.getNumEnvironmentVars(); ++i)
@@ -8,10 +8,12 @@
 #include <set>
 #include <limits>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>
+
 #include "Mutex.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "utils/StringUtils.h"
 #include "transforms/FileTransform.h"

@@ -24,7 +26,6 @@
 #include "mz_strm_mem.h"
 #include "mz_strm_os.h"
 #include "mz_strm_split.h"
-#include "mz_strm_zlib.h"
 #include "mz_zip.h"
 #include "mz_zip_rw.h"

@@ -4,6 +4,8 @@
 #include <cstring>
 #include <sstream>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "Logging.h"
@@ -20,7 +22,6 @@
 #include "ops/lut1d/Lut1DOp.h"
 #include "ops/lut3d/Lut3DOp.h"
 #include "ops/range/RangeOp.h"
-#include "pystring/pystring.h"

 namespace OCIO_NAMESPACE
 {
@@ -5,12 +5,13 @@
 #include <iostream>
 #include <map>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "Mutex.h"
 #include "PathUtils.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "utils/StringUtils.h"
 #include "OCIOZArchive.h"

@@ -218,4 +219,3 @@ int ParseColorSpaceFromString(const Config & config, const char * str)
 }

 } // namespace OCIO_NAMESPACE
-
@@ -18,8 +18,6 @@
    #endif
 #endif

-#include <stdio.h>
-
 #include <OpenColorIO/OpenColorIO.h>
 #include "BitDepthUtils.h"

@@ -76,6 +74,8 @@ static inline void sse2RGBATranspose_4x4(__m128 row0, __m128 row1, __m128 row2,
    out_a = _mm_movehl_ps(tmp3, tmp1);
 }

+#if !OCIO_USE_SSE2NEON
+
 static inline __m128i sse2_blendv(__m128i a, __m128i b, __m128i mask)
 {
    return _mm_xor_si128(_mm_and_si128(_mm_xor_si128(a, b), mask), a);
@@ -164,6 +164,8 @@ static inline __m128 sse2_cvtph_ps(__m128i a)
    return  _mm_or_ps(o, sign);
 }

+#endif
+
 // Note Packing functions perform no 0.0 - 1.0 normalization
 // but perform 0 - max value clamping for integer formats
 template<BitDepth BD> struct SSE2RGBAPack {};
@@ -290,21 +292,48 @@ struct SSE2RGBAPack<BIT_DEPTH_F16>
        __m128i rgba_00_01 = _mm_loadu_si128((const __m128i*)(in + 0));
        __m128i rgba_02_03 = _mm_loadu_si128((const __m128i*)(in + 8));

+#if OCIO_USE_SSE2NEON
+        // use neon hardware support for f16 to f32
+        __m128 rgba0 = vreinterpretq_m128_f32(
+            vcvt_f32_f16(vget_low_f16(vreinterpretq_f16_s64(vreinterpretq_s64_m128i(rgba_00_01))))
+        );
+        __m128 rgba1 = vreinterpretq_m128_f32(
+            vcvt_f32_f16(vget_high_f16(vreinterpretq_f16_s64(vreinterpretq_s64_m128i(rgba_00_01))))
+        );
+        __m128 rgba2 = vreinterpretq_m128_f32(
+            vcvt_f32_f16(vget_low_f16(vreinterpretq_f16_s64(vreinterpretq_s64_m128i(rgba_02_03))))
+        );
+        __m128 rgba3 = vreinterpretq_m128_f32(
+            vcvt_f32_f16(vget_high_f16(vreinterpretq_f16_s64(vreinterpretq_s64_m128i(rgba_02_03))))
+        );
+#else
        __m128 rgba0 = sse2_cvtph_ps(rgba_00_01);
        __m128 rgba1 = sse2_cvtph_ps(_mm_shuffle_epi32(rgba_00_01, _MM_SHUFFLE(1,0,3,2)));
        __m128 rgba2 = sse2_cvtph_ps(rgba_02_03);
        __m128 rgba3 = sse2_cvtph_ps(_mm_shuffle_epi32(rgba_02_03, _MM_SHUFFLE(1,0,3,2)));
-
+#endif
        sse2RGBATranspose_4x4(rgba0, rgba1, rgba2, rgba3, r, g, b, a);
    }

    static inline  void Store(half *out, __m128 r, __m128 g, __m128 b, __m128 a)
    {
        __m128 rgba0, rgba1, rgba2, rgba3;
-        __m128i rgba;
-
        sse2RGBATranspose_4x4(r, g, b, a, rgba0, rgba1, rgba2, rgba3);

+#if OCIO_USE_SSE2NEON
+        // use neon hardware support for f32 to f16
+        float16x8_t rgba;
+        float16x4_t rgba00_01 = vcvt_f16_f32(vreinterpretq_f32_m128(rgba0));
+        float16x4_t rgba03_03 = vcvt_f16_f32(vreinterpretq_f32_m128(rgba1));
+        float16x4_t rgba04_05 = vcvt_f16_f32(vreinterpretq_f32_m128(rgba2));
+        float16x4_t rgba06_07 = vcvt_f16_f32(vreinterpretq_f32_m128(rgba3));
+        rgba = vcombine_f16(rgba00_01, rgba03_03);
+        vst1q_f16((float16_t *)(out+0), rgba);
+
+        rgba = vcombine_f16(rgba04_05, rgba06_07);
+        vst1q_f16((float16_t *)(out+8), rgba);
+#else
+        __m128i rgba;
        __m128i rgba00_01 = sse2_cvtps_ph(rgba0);
        __m128i rgba02_03 = sse2_cvtps_ph(rgba1);
        __m128i rgba04_05 = sse2_cvtps_ph(rgba2);
@@ -315,6 +344,7 @@ struct SSE2RGBAPack<BIT_DEPTH_F16>

        rgba = _mm_xor_si128(rgba04_05, _mm_shuffle_epi32(rgba06_07, _MM_SHUFFLE(1,0,3,2)));
        _mm_storeu_si128((__m128i*)(out+8), rgba);
+#endif
    }
 };

@@ -217,7 +217,7 @@ void LocalFileFormat::buildFileOps(OpRcPtrVec & ops,
    {
        // Use 0 for empty string.
        int cccindex=0;
-        if (StringToInt(&cccindex, cccid.c_str(), true))
+        if (cccid.empty() || StringToInt(&cccindex, cccid.c_str(), true))
        {
            int maxindex = ((int)cachedFile->m_transformVec.size())-1;
            if (cccindex<0 || cccindex>maxindex)
@@ -247,7 +247,7 @@ LocalFileFormat::buildFileOps(OpRcPtrVec & ops,
    {
        // Use 0 for empty string.
        int cccindex=0;
-        if (StringToInt(&cccindex, cccid.c_str(), true))
+        if (cccid.empty() || StringToInt(&cccindex, cccid.c_str(), true))
        {
            int maxindex = ((int)cachedFile->m_transformVec.size())-1;
            if (cccindex<0 || cccindex>maxindex)
@@ -274,7 +274,7 @@ LocalFileFormat::buildFileOps(OpRcPtrVec & ops,
    if (!success)
    {
        std::ostringstream os;
-        os << "You must specify a valid cccid to load from the ccc file";
+        os << "You must specify a valid cccid to load from the cdl file";
        os << " (either by name or index). id='" << cccid << "' ";
        os << "is not found in the file, and is not parsable as an ";
        os << "integer index.";
@@ -6,6 +6,8 @@
 #include <fstream>
 #include <sstream>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "expat.h"
@@ -23,7 +25,6 @@
 #include "OpBuilders.h"
 #include "ops/noop/NoOps.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "TransformBuilder.h"
 #include "transforms/FileTransform.h"
 #include "utils/StringUtils.h"
@@ -8,6 +8,8 @@
 #include <sstream>
 #include <iostream>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "BitDepthUtils.h"
@@ -16,7 +18,6 @@
 #include "ops/lut1d/Lut1DOp.h"
 #include "ops/lut3d/Lut3DOp.h"
 #include "ParseUtils.h"
-#include "pystring/pystring.h"
 #include "Platform.h"
 #include "transforms/FileTransform.h"
 #include "utils/StringUtils.h"
@@ -771,4 +772,3 @@ FileFormat * CreateFileFormatDiscreet1DL()
 }

 } // namespace OCIO_NAMESPACE
-
@@ -5,6 +5,8 @@
 #include <sstream>
 #include <fstream>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "Logging.h"
@@ -15,7 +17,6 @@
 #include "ops/matrix/MatrixOp.h"
 #include "ops/range/RangeOp.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "transforms/FileTransform.h"


@@ -5,6 +5,8 @@
 #include <cstring>
 #include <iterator>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "expat.h"
@@ -13,7 +15,6 @@
 #include "ops/lut3d/Lut3DOp.h"
 #include "ParseUtils.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "transforms/FileTransform.h"
 #include "utils/StringUtils.h"
 #include "utils/NumberUtils.h"
@@ -579,4 +580,3 @@ FileFormat * CreateFileFormatIridasLook()
 }

 } // namespace OCIO_NAMESPACE
-
@@ -24,13 +24,23 @@ namespace {

 static inline __m128 fmadd_ps_sse2(__m128 a, __m128 b, __m128 c)
 {
+#if OCIO_USE_SSE2NEON
+    return vreinterpretq_m128_f32(
+        vfmaq_f32(vreinterpretq_f32_m128(c), vreinterpretq_f32_m128(a), vreinterpretq_f32_m128(b))
+    );
+#else
    return  _mm_add_ps(_mm_mul_ps(a, b), c);
+#endif
 }

 static inline __m128 floor_ps_sse2(__m128 v)
 {
+#if OCIO_USE_SSE2NEON
+    return _mm_floor_ps(v);
+#else
    // NOTE: using truncate cvtt
    return _mm_cvtepi32_ps(_mm_cvttps_epi32(v));
+#endif
 }


@@ -38,18 +38,32 @@ struct rgbavec_sse2 {

 static inline __m128 floor_ps_sse2(__m128 v)
 {
+#if OCIO_USE_SSE2NEON
+    return _mm_floor_ps(v);
+#else
    // NOTE: using truncate cvtt
    return _mm_cvtepi32_ps(_mm_cvttps_epi32(v));
+#endif
 }

 static inline __m128 blendv_ps_sse2(__m128 a, __m128 b, __m128 mask)
 {
+#if OCIO_USE_SSE2NEON
+    return _mm_blendv_ps(a, b, mask);
+#else
    return _mm_xor_ps(_mm_and_ps(_mm_xor_ps(a, b), mask), a);
+#endif
 }

 static inline __m128 fmadd_ps_sse2(__m128 a, __m128 b, __m128 c)
 {
+#if OCIO_USE_SSE2NEON
+    return vreinterpretq_m128_f32(
+        vfmaq_f32(vreinterpretq_f32_m128(c), vreinterpretq_f32_m128(a), vreinterpretq_f32_m128(b))
+    );
+#else
    return  _mm_add_ps(_mm_mul_ps(a, b), c);
+#endif
 }

 static inline rgbavec_sse2 interp_tetrahedral_sse2(const Lut3DContextSSE2 &ctx, __m128 r, __m128 g, __m128 b, __m128 a)
@@ -184,7 +184,7 @@ void BuildColorSpaceOps(OpRcPtrVec & ops,

    if (!src)
    {
-        srcNamedTransform = config.getNamedTransform(srcName.c_str());
+        srcNamedTransform = config.getNamedTransform( context->resolveStringVar(srcName.c_str()) );
        if (!srcNamedTransform)
        {
            ThrowMissingCS(srcName.c_str());
@@ -192,7 +192,7 @@ void BuildColorSpaceOps(OpRcPtrVec & ops,
    }
    if (!dst)
    {
-        dstNamedTransform = config.getNamedTransform(dstName.c_str());
+        dstNamedTransform = config.getNamedTransform( context->resolveStringVar(dstName.c_str()) );
        if (!dstNamedTransform)
        {
            ThrowMissingCS(dstName.c_str());
@@ -393,6 +393,31 @@ void BuildReferenceConversionOps(OpRcPtrVec & ops,
    }
 }

+bool CollectContextVariables(const Config & config, 
+                             const Context & context,
+                             ConstNamedTransformRcPtr & nt,
+                             ContextRcPtr & usedContextVars)
+{
+    bool foundContextVars = false;
+
+    if (nt)
+    {
+        ConstTransformRcPtr to = nt->getTransform(TRANSFORM_DIR_FORWARD);
+        if (to && CollectContextVariables(config, context, to, usedContextVars))
+        {
+            foundContextVars = true;
+        }
+
+        ConstTransformRcPtr from = nt->getTransform(TRANSFORM_DIR_INVERSE);
+        if (from && CollectContextVariables(config, context, from, usedContextVars))
+        {
+            foundContextVars = true;
+        }
+    }
+
+    return foundContextVars;
+}
+
 bool CollectContextVariables(const Config & config, 
                             const Context & context,
                             ConstColorSpaceRcPtr & cs,
@@ -441,15 +466,37 @@ bool CollectContextVariables(const Config & config,
    }

    ConstColorSpaceRcPtr src = config.getColorSpace(srcName.c_str());
-    if (CollectContextVariables(config, context, src, usedContextVars))
+    if (src)
    {
-        foundContextVars = true;
+        if (CollectContextVariables(config, context, src, usedContextVars))
+        {
+            foundContextVars = true;
+        }
+    }
+    else
+    {
+        ConstNamedTransformRcPtr nt_src = config.getNamedTransform(srcName.c_str());
+        if (CollectContextVariables(config, context, nt_src, usedContextVars))
+        {
+            foundContextVars = true;
+        }
    }

    ConstColorSpaceRcPtr dst = config.getColorSpace(dstName.c_str());
-    if (CollectContextVariables(config, context, dst, usedContextVars))
+    if (dst)
    {
-        foundContextVars = true;
+        if (CollectContextVariables(config, context, dst, usedContextVars))
+        {
+            foundContextVars = true;
+        }
+    }
+    else
+    {
+        ConstNamedTransformRcPtr nt_dst = config.getNamedTransform(dstName.c_str());
+        if (CollectContextVariables(config, context, nt_dst, usedContextVars))
+        {
+            foundContextVars = true;
+        }
    }

    return foundContextVars;
@@ -9,6 +9,8 @@
 #include <iostream>
 #include <iterator>

+#include <pystring.h>
+
 #include <OpenColorIO/OpenColorIO.h>

 #include "Caching.h"
@@ -19,7 +21,6 @@
 #include "ops/noop/NoOps.h"
 #include "PathUtils.h"
 #include "Platform.h"
-#include "pystring/pystring.h"
 #include "utils/StringUtils.h"

 namespace OCIO_NAMESPACE
@@ -50,12 +50,16 @@ public:
    void setGPU(OCIO::ConstGPUProcessorRcPtr gpu)
    {
        m_gpu = gpu;
-        m_oglApp = OCIO::OglApp::CreateOglApp("ociochecklut", 256, 20);
-
-        if (m_verbose)
+        if (!m_oglApp)
        {
-            m_oglApp->printGLInfo();
+            m_oglApp = OCIO::OglApp::CreateOglApp("ociochecklut", 256, 20);
+
+            if (m_verbose)
+            {
+                m_oglApp->printGLInfo();
+            }
        }
+
        m_oglApp->setPrintShader(m_verbose);
        float image[4]{ 0.f, 0.f, 0.f, 0.f };
        m_oglApp->initImage(1, 1, OCIO::OglApp::COMPONENTS_RGBA, image);
@@ -191,6 +195,7 @@ int main (int argc, const char* argv[])
    bool usegpu        = false;
    bool usegpuLegacy  = false;
    bool outputgpuInfo = false;
+    bool stepInfo      = false;

    ArgParse ap;
    ap.options("ociochecklut -- check any LUT file and optionally convert a pixel\n\n"
@@ -199,6 +204,7 @@ int main (int argc, const char* argv[])
               "<SEPARATOR>", "Options:",
               "-t", &test, "Test a set a predefined RGB values",
               "-v", &verbose, "Verbose",
+               "-s", &stepInfo, "Print the output after each step in a multi - transform LUT",
               "--help", &help, "Print help message",
               "--inv", &invlut, "Apply LUT in inverse direction",
               "--gpu", &usegpu, "Use GPU instead of CPU",
@@ -346,7 +352,7 @@ int main (int argc, const char* argv[])
              0.f,   1.f,   0.f,
              0.f,   0.f,   1.f };

-        if (verbose)
+        if (verbose || stepInfo)
        {
            std::cout << std::endl;
        }
@@ -357,59 +363,140 @@ int main (int argc, const char* argv[])
            {
                std::vector<float> pixel = { input[curPix], input[curPix+1], input[curPix+2],
                                             comp == 3 ? 0.0f : input[curPix + 3] };
-                try
-                {
-                    proc.apply(pixel);
-                }
-                catch (const OCIO::Exception & e)
-                {
-                    std::cerr << "ERROR: Processing pixel: " << e.what() << std::endl;
-                    return 1;
-                }
-                catch (...)
-                {
-                    std::cerr << "ERROR: Unknown error encountered while processing pixel." << std::endl;
-                    return 1;
-                }

-                // Print to string so that in & out values can be aligned if needed.
-
-                std::vector<std::string> out;
-                ToString(out, pixel, 0, comp);
-
-                if (verbose)
+                if (stepInfo)
                {
-                    std::vector<std::string> in;
-                    ToString(in, input, curPix, comp);
-
-                    std::cout << "Input  [R G B";
-                    if (comp == 4)
+                    // Process each step in a multi - transform LUT
+                    try
                    {
-                        std::cout << " A";
-                    }
-                    std::cout << "]: [";
-                    PrintAlignedVec(in, out, comp);
-                    std::cout << "]" << std::endl;
+                        // Create GroupTransform so that each can be processed one at a time. 
+                        auto processor = config->getProcessor(t);
+                        auto transform = processor->createGroupTransform();
+                        std::vector<float> inputPixel = pixel;
+                        std::vector<float> outputPixel = pixel;
+                        const auto numTransforms = transform->getNumTransforms();
+                        
+                        std::cout << std::endl;

-                    std::cout << "Output [R G B";
-                    if (comp == 4)
-                    {
-                        std::cout << " A";
+                        for (int i = 0; i < numTransforms; ++i)
+                        {
+                            auto transformStep = transform->getTransform(i);
+                            auto processorStep = config->getProcessor(transformStep);
+
+                            if (usegpu || usegpuLegacy)
+                            {
+                                proc.setGPU(usegpuLegacy ? processorStep->getOptimizedLegacyGPUProcessor(OCIO::OPTIMIZATION_DEFAULT, 32)
+                                    : processorStep->getDefaultGPUProcessor());
+                            }
+                            else
+                            {
+                                proc.setCPU(processorStep->getDefaultCPUProcessor());
+                            }
+                            
+                            // Process the pixel
+                            proc.apply(outputPixel);
+
+                            // Print the input/output pixel
+                            std::vector<std::string> in;
+                            ToString(in, inputPixel, 0, comp);
+
+                            std::vector<std::string> out;
+                            ToString(out, outputPixel, 0, comp);
+
+                            std::cout << "\n" << *(transform->getTransform(i)) << std::endl;
+                            std::cout << "Input  [R G B";
+                            if (comp == 4)
+                            {
+                                std::cout << " A";
+                            }
+                            std::cout << "]: [";
+                            PrintAlignedVec(in, out, comp);
+                            std::cout << "]" << std::endl;
+
+                            std::cout << "Output [R G B";
+                            if (comp == 4)
+                            {
+                                std::cout << " A";
+                            }
+                            std::cout << "]: [";
+                            PrintAlignedVec(out, in, comp);
+                            std::cout << "]" << std::endl;
+
+                            inputPixel = outputPixel;         
+                        }
                    }
-                    std::cout << "]: [";
-                    PrintAlignedVec(out, in, comp);
-                    std::cout << "]" << std::endl;
+                    catch (const OCIO::Exception& exception)
+                    {
+                        std::cerr << "ERROR: " << exception.what() << std::endl;
+                        return 1;
+                    }
+                    catch (...)
+                    {
+                        std::cerr << "ERROR: Unknown error encountered while processing single step operator." << std::endl;
+                        return 1;
+                    }
+
+                    curPix += comp;
                }
                else
                {
-                    std::cout << out[0] << " " << out[1] << " " << out[2];
-                    if (comp == 4)
+                    // Process in a single step
+                    try
                    {
-                        std::cout << " " << out[3];
+                        proc.apply(pixel);
                    }
+                    catch (const OCIO::Exception& e)
+                    {
+                        std::cerr << "ERROR: Processing pixel: " << e.what() << std::endl;
+                        return 1;
+                    }
+                    catch (...)
+                    {
+                        std::cerr << "ERROR: Unknown error encountered while processing pixel." << std::endl;
+                        return 1;
+                    }
+
+                    // Print to string so that in & out values can be aligned if needed.
+
+                    std::vector<std::string> out;
+                    ToString(out, pixel, 0, comp);
+
                    std::cout << std::endl;
-                }
-                curPix += comp;
+
+                    if (verbose)
+                    {
+                        std::vector<std::string> in;
+                        ToString(in, input, curPix, comp);
+
+                        std::cout << "Input  [R G B";
+                        if (comp == 4)
+                        {
+                            std::cout << " A";
+                        }
+                        std::cout << "]: [";
+                        PrintAlignedVec(in, out, comp);
+                        std::cout << "]" << std::endl;
+
+                        std::cout << "Output [R G B";
+                        if (comp == 4)
+                        {
+                            std::cout << " A";
+                        }
+                        std::cout << "]: [";
+                        PrintAlignedVec(out, in, comp);
+                        std::cout << "]" << std::endl;
+                    }
+                    else
+                    {
+                        std::cout << out[0] << " " << out[1] << " " << out[2];
+                        if (comp == 4)
+                        {
+                            std::cout << " " << out[3];
+                        }
+                        std::cout << std::endl;
+                    }
+                    curPix += comp;
+                }               
            }
            else if (test)
            {
@@ -41,10 +41,10 @@ Dependencies

 * PyOpenColorIO
 * [OpenImageIO (Python bindings)](https://github.com/OpenImageIO/oiio)
-* [Imath (Python bindings)](https://github.com/AcademySoftwareFoundation/Imath)
 * ``pip install -r requirements.txt``
  * [numpy](https://pypi.org/project/numpy/)
  * [Pygments](https://pypi.org/project/Pygments/)
  * [PyOpenGL](https://pypi.org/project/PyOpenGL/)
-  * [PySide2](https://pypi.org/project/PySide2/)
+  * [PySide6](https://pypi.org/project/PySide6/)
  * [QtAwesome](https://pypi.org/project/QtAwesome/)
+  * [imageio](https://pypi.org/project/imageio/)
@@ -7,7 +7,7 @@ import sys
 from pathlib import Path

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets, QtOpenGL
+from PySide6 import QtCore, QtGui, QtWidgets, QtOpenGL

 import ocioview.log_handlers  # Import to initialize logging
 from ocioview.main_window import OCIOView
@@ -30,12 +30,11 @@ if __name__ == "__main__":
    sys.excepthook = excepthook

    # OpenGL core profile needed on macOS to access programmatic pipeline
-    gl_format = QtOpenGL.QGLFormat()
-    gl_format.setProfile(QtOpenGL.QGLFormat.CoreProfile)
-    gl_format.setSampleBuffers(True)
+    gl_format = QtGui.QSurfaceFormat()
+    gl_format.setProfile(QtGui.QSurfaceFormat.CoreProfile)
    gl_format.setSwapInterval(1)
    gl_format.setVersion(4, 0)
-    QtOpenGL.QGLFormat.setDefaultFormat(gl_format)
+    QtGui.QSurfaceFormat.setDefaultFormat(gl_format)

    # Create app
    app = QtWidgets.QApplication(sys.argv)
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from .items import (
    ColorSpaceEdit,
@@ -3,7 +3,7 @@

 from pathlib import Path

-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui


 # Root application directory
@@ -6,7 +6,7 @@ from typing import Optional

 import PyOpenColorIO as ocio
 from pygments.formatters import HtmlFormatter
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..message_router import MessageRouter
 from ..utils import get_glyph_icon, processor_to_shader_html
@@ -40,9 +40,9 @@ class CodeInspector(QtWidgets.QWidget):

        html_css = HtmlFormatter(style="material").get_style_defs()
        # Update line number colors to match palette
-        html_css = html_css.replace("#263238", palette.color(palette.Base).name())
+        html_css = html_css.replace("#263238", palette.color(palette.ColorRole.Base).name())
        html_css = html_css.replace(
-            "#37474F", palette.color(palette.Text).darker(150).name()
+            "#37474F", palette.color(palette.ColorRole.Text).darker(150).name()
        )

        # Widgets
@@ -8,7 +8,7 @@ from typing import Optional
 import numpy as np

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..constants import R_COLOR, G_COLOR, B_COLOR, GRAY_COLOR
 from ..message_router import MessageRouter
@@ -17,11 +17,22 @@ from ..widgets import EnumComboBox, FloatEditArray, IntEdit


 class SampleType(enum.Enum):
+    """Enum of curve sampling types for representing OCIO transforms."""
+
    LINEAR = "linear"
+    """Linear scale."""
+
    LOG = "log"
+    """Log scale with a user-defined base."""


 class CurveInspector(QtWidgets.QWidget):
+    """
+    Widget for inspecting OCIO transform tone curves, which updates
+    asynchronously when visible, to reduce unnecessary background
+    processing.
+    """
+
    @classmethod
    def label(cls) -> str:
        return "Curve"
@@ -43,11 +54,11 @@ class CurveInspector(QtWidgets.QWidget):
        self.input_range_edit.setToolTip(self.input_range_label.toolTip())
        self.input_range_edit.value_changed.connect(self._on_input_range_changed)

-        self.sample_size_label = get_glyph_icon("ph.line-segments", as_widget=True)
-        self.sample_size_label.setToolTip("Sample size")
-        self.sample_size_edit = IntEdit(default=CurveView.SAMPLE_SIZE_DEFAULT)
-        self.sample_size_edit.setToolTip(self.sample_size_label.toolTip())
-        self.sample_size_edit.value_changed.connect(self._on_sample_size_changed)
+        self.sample_count_label = get_glyph_icon("ph.line-segments", as_widget=True)
+        self.sample_count_label.setToolTip("Sample count")
+        self.sample_count_edit = IntEdit(default=CurveView.SAMPLE_COUNT_DEFAULT)
+        self.sample_count_edit.setToolTip(self.sample_count_label.toolTip())
+        self.sample_count_edit.value_changed.connect(self._on_sample_count_changed)

        self.sample_type_label = get_glyph_icon("mdi6.function-variant", as_widget=True)
        self.sample_type_label.setToolTip("Sample type")
@@ -70,16 +81,16 @@ class CurveInspector(QtWidgets.QWidget):
        option_layout = QtWidgets.QHBoxLayout()
        option_layout.addWidget(self.input_range_label)
        option_layout.addWidget(self.input_range_edit)
-        option_layout.setStretch(1, 2)
-        option_layout.addWidget(self.sample_size_label)
-        option_layout.addWidget(self.sample_size_edit)
-        option_layout.setStretch(3, 1)
+        option_layout.setStretch(1, 3)
+        option_layout.addWidget(self.sample_count_label)
+        option_layout.addWidget(self.sample_count_edit)
+        option_layout.setStretch(3, 2)
        option_layout.addWidget(self.sample_type_label)
        option_layout.addWidget(self.sample_type_combo)
-        option_layout.setStretch(5, 1)
+        option_layout.setStretch(5, 3)
        option_layout.addWidget(self.log_base_label)
        option_layout.addWidget(self.log_base_edit)
-        option_layout.setStretch(7, 1)
+        option_layout.setStretch(7, 2)

        layout = QtWidgets.QVBoxLayout()
        layout.addLayout(option_layout)
@@ -88,83 +99,137 @@ class CurveInspector(QtWidgets.QWidget):
        self.setLayout(layout)

    def reset(self) -> None:
+        """Clear rendered curves."""
        self.view.reset()

    @QtCore.Slot(str, float)
    def _on_input_range_changed(self, label: str, value: float) -> None:
+        """
+        Triggered when the user changes the input range, which defines
+        the input values to be sampled through the transform.
+
+        :param label: Float edit label
+        :param value: Float edit value
+        """
        self.view.set_input_range(
            self.input_range_edit.component_value("min"),
            self.input_range_edit.component_value("max"),
        )

    @QtCore.Slot(int)
-    def _on_sample_size_changed(self, sample_size: int) -> None:
-        if sample_size >= CurveView.SAMPLE_SIZE_MIN:
-            self.view.set_sample_size(sample_size)
+    def _on_sample_count_changed(self, sample_count: int) -> None:
+        """
+        Triggered when the user changes the number of samples to be
+        processed within the input range through the transform.
+
+        :param sample_count: Number of samples. Typically, a power of 2
+            number.
+        """
+        if sample_count >= CurveView.SAMPLE_COUNT_MIN:
+            self.view.set_sample_count(sample_count)
        else:
-            with SignalsBlocked(self.sample_size_edit):
-                self.sample_size_edit.set_value(CurveView.SAMPLE_SIZE_MIN)
-                self.view.set_sample_size(CurveView.SAMPLE_SIZE_MIN)
+            with SignalsBlocked(self.sample_count_edit):
+                self.sample_count_edit.set_value(CurveView.SAMPLE_COUNT_MIN)
+                self.view.set_sample_count(CurveView.SAMPLE_COUNT_MIN)

    @QtCore.Slot(int)
    def _on_sample_type_changed(self, index: int) -> None:
+        """
+        Triggered when the user changes the sample type, which defines
+        how samples are distributed within the input range.
+
+        :param index: Curve type index
+        """
        sample_type = self.sample_type_combo.member()
        self.log_base_edit.setEnabled(sample_type == SampleType.LOG)
        self.view.set_sample_type(sample_type)

    @QtCore.Slot(int)
    def _on_log_base_changed(self, log_base: int) -> None:
+        """
+        Triggered when the user changes the base for the log sample
+        type.
+
+        :param log_base: Log scale base
+        """
        self.view.set_log_base(log_base)


 class CurveView(QtWidgets.QGraphicsView):
+    """
+    Widget for rendering OCIO transform tone curves.
+    """

-    SAMPLE_SIZE_MIN = 2**8
-    SAMPLE_SIZE_DEFAULT = 2**10
+    SAMPLE_COUNT_MIN = 2**8
+    SAMPLE_COUNT_DEFAULT = 2**10
    INPUT_MIN_DEFAULT = 0.0
    INPUT_MAX_DEFAULT = 1.0
+    LOG_BASE_DEFAULT = 2
    CURVE_SCALE = 100
    FONT_HEIGHT = 4

    # The curve viewer only shows 5 digit decimal precision, so this should work fine
    # as a minimum when input min is 0.
-    LOG_EPSILON = 1e-5
-    LOG_BASE_DEFAULT = 2
+    EPSILON = 1e-5

    def __init__(
        self,
        input_min: float = INPUT_MIN_DEFAULT,
        input_max: float = INPUT_MAX_DEFAULT,
-        sample_size: int = SAMPLE_SIZE_DEFAULT,
+        sample_count: int = SAMPLE_COUNT_DEFAULT,
        sample_type: SampleType = SampleType.LINEAR,
        log_base: int = LOG_BASE_DEFAULT,
        parent: Optional[QtWidgets.QWidget] = None,
    ):
+        """
+        :param input_min: Input range minimum value
+        :param input_max: Input range maximum value
+        :param sample_count: Number of samples in the input range,
+            which will typically be a power of 2 value.
+        :param sample_type: Sample scale/distribution type
+        :param log_base: Log scale base when sample_type is
+            `SampleType.LOG`.
+        """
        super().__init__(parent=parent)
        self.setRenderHint(QtGui.QPainter.Antialiasing, True)
        self.setViewportUpdateMode(QtWidgets.QGraphicsView.FullViewportUpdate)
        self.setHorizontalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setVerticalScrollBarPolicy(QtCore.Qt.ScrollBarAlwaysOff)
        self.setMouseTracking(True)
-        self.scale(1, -1)
+        self.scale(1, -1)  # Flip to make origin the bottom-left corner

+        # Input  range
        if input_max <= input_min:
            input_min = self.INPUT_MIN_DEFAULT
            input_max = self.INPUT_MAX_DEFAULT

-        self._log_base = max(2, log_base)
        self._input_min = input_min
        self._input_max = input_max
-        self._sample_size = max(self.SAMPLE_SIZE_MIN, sample_size)
+
+        # Sample characteristics
+        self._sample_count = max(self.SAMPLE_COUNT_MIN, sample_count)
        self._sample_type = sample_type
+        self._log_base = max(2, log_base)
+
+        # Cached sample data
        self._sample_ellipse: Optional[QtWidgets.QGraphicsEllipseItem] = None
        self._sample_text: Optional[QtWidgets.QGraphicsTextItem] = None
        self._sample_rect: Optional[QtCore.QRectF] = None
-        self._samples_x_lin: np.ndarray = None
-        self._samples_x_log: np.ndarray = None
-        self._sample_y_min: float = self._input_min
-        self._sample_y_max: float = self._input_max
+
        self._samples: dict[str, np.ndarray] = {}
+        self._nearest_samples: dict[str, tuple[float, float, float]] = {}
+
+        self._x_lin: np.ndarray = np.array([], dtype=np.float32)
+        self._x_log: np.ndarray = np.array([], dtype=np.float32)
+        self._x_min: float = self._input_min
+        self._x_max: float = self._input_max
+        self._y_min: float = self._input_min
+        self._y_max: float = self._input_max
+
+        # Cached curve data
+        self._curve_init = False
+        self._curve_tf = QtGui.QTransform()
+        self._curve_tf_inv = QtGui.QTransform()
        self._curve_paths: dict[str, QtGui.QPainterPath] = {}
        self._curve_items: dict[str, QtWidgets.QGraphicsPathItem] = {}
        self._curve_rect = QtCore.QRectF(
@@ -173,10 +238,11 @@ class CurveView(QtWidgets.QGraphicsView):
            self._input_max - self._input_min,
            self._input_max - self._input_min,
        )
-        self._nearest_samples: dict[str, tuple[float, float, float]] = {}
-        self._prev_cpu_proc = None
-        self._curve_init = False

+        # Cached processor from which the OCIO transform is derived
+        self._prev_cpu_proc = None
+
+        # Graphics scene
        self._scene = QtWidgets.QGraphicsScene()
        self.setScene(self._scene)

@@ -200,8 +266,8 @@ class CurveView(QtWidgets.QGraphicsView):
        msg_router.set_cpu_processor_updates_allowed(False)

    def resizeEvent(self, event: QtGui.QResizeEvent) -> None:
+        """Re-fit graph on resize, to always be centered."""
        super().resizeEvent(event)
-
        self._fit()

    def mouseMoveEvent(self, event: QtGui.QMouseEvent) -> None:
@@ -213,37 +279,52 @@ class CurveView(QtWidgets.QGraphicsView):

        self._nearest_samples.clear()

-        pos = self.mapToScene(event.pos()) / self.CURVE_SCALE
+        pos = self._curve_tf_inv.map(self.mapToScene(event.pos()))
        pos_arr = np.array([pos.x(), pos.y()], dtype=np.float32)

        for color_name, samples in self._samples.items():
-            all_dist = np.linalg.norm(samples - pos_arr, axis=2)
+            all_dist = np.linalg.norm(samples - pos_arr, axis=1)
            nearest_dist_index = np.argmin(all_dist)
            self._nearest_samples[color_name] = (
                (
-                    self._samples_x_lin[nearest_dist_index]
+                    self._x_lin[nearest_dist_index]
                    if self._sample_type == SampleType.LINEAR
-                    else self._samples_x_log[nearest_dist_index]
+                    else self._x_log[nearest_dist_index]
                ),
-                samples[0][nearest_dist_index][0],
-                samples[0][nearest_dist_index][1],
+                samples[nearest_dist_index][0],
+                samples[nearest_dist_index][1],
            )

        self._invalidate()

+    def wheelEvent(self, event: QtGui.QWheelEvent) -> None:
+        """
+        Ignore wheel events to prevent scrolling around graphics scene.
+        """
+        event.ignore()
+
    def reset(self) -> None:
        """Clear all curves."""
        self._samples.clear()
-        self._curve_items.clear()
-        self._curve_paths.clear()
        self._nearest_samples.clear()
-        self._prev_cpu_proc = None
+
        self._curve_init = False
+        self._curve_paths.clear()
+        self._curve_items.clear()
+
+        self._prev_cpu_proc = None

        self._scene.clear()
        self._invalidate()

    def set_input_range(self, input_min: float, input_max: float) -> None:
+        """
+        Set the input range, which defines the input values to be
+        sampled through the transform.
+
+        :param input_min: Input range minimum value
+        :param input_max: Input range maximum value
+        """
        if (
            input_min != self._input_min or input_max != self._input_max
        ) and input_max > input_min:
@@ -252,31 +333,62 @@ class CurveView(QtWidgets.QGraphicsView):
            self._update_curves()

    def set_input_min(self, input_min: float) -> None:
+        """
+        Set the input minimum, which defines the lowest value to be
+        sampled through the transform.
+
+        :param input_min: Input range minimum value
+        """
        if input_min != self._input_min and input_min < self._input_max:
            self._input_min = input_min
            self._update_curves()

    def set_input_max(self, input_max: float) -> None:
+        """
+        Set the input maximum, which defines the highest value to be
+        sampled through the transform.
+
+        :param input_max: Input range minimum value
+        """
        if input_max != self._input_max and input_max > self._input_min:
            self._input_max = input_max
            self._update_curves()

-    def set_sample_size(self, sample_size: int) -> None:
-        if sample_size != self._sample_size and sample_size >= self.SAMPLE_SIZE_MIN:
-            self._sample_size = sample_size
+    def set_sample_count(self, sample_count: int) -> None:
+        """
+        Set the number of samples to be processed within the input
+        range through the transform.
+
+        :param sample_count: Number of samples. Typically, a power of 2
+            number.
+        """
+        if sample_count != self._sample_count and sample_count >= self.SAMPLE_COUNT_MIN:
+            self._sample_count = sample_count
            self._update_curves()

    def set_sample_type(self, sample_type: SampleType) -> None:
+        """
+        Set the sample type, which defines how samples are distributed
+        within the input range.
+
+        :param sample_type: Curve type index
+        """
        if sample_type != self._sample_type:
            self._sample_type = sample_type
            self._update_curves()

    def set_log_base(self, log_base: int) -> None:
+        """
+        Set the base for the log sample type.
+
+        :param log_base: Log scale base
+        """
        if log_base != self._log_base and log_base >= 2:
            self._log_base = log_base
            self._update_curves()

    def drawBackground(self, painter: QtGui.QPainter, rect: QtCore.QRectF) -> None:
+        """Draw curve grid and axis values."""
        # Flood fill background
        painter.setPen(QtCore.Qt.NoPen)
        painter.setBrush(QtCore.Qt.black)
@@ -285,101 +397,41 @@ class CurveView(QtWidgets.QGraphicsView):
        if not self._curve_init:
            return

-        # Calculate grid rect
-        curve_t, curve_b, curve_l, curve_r = (
-            self._curve_rect.top(),
-            self._curve_rect.bottom(),
-            self._curve_rect.left(),
-            self._curve_rect.right(),
-        )
-
-        # Round to nearest 10 for grid bounds
-        grid_t = curve_t // 10 * 10
-        if grid_t > math.ceil(curve_t):
-            grid_t -= 10
-        grid_b = curve_b // 10 * 10
-        if grid_b < math.floor(curve_b):
-            grid_b += 10
-        grid_l = curve_l // 10 * 10
-        if grid_l > math.ceil(curve_l):
-            grid_l -= 10
-        grid_r = curve_r // 10 * 10
-        if grid_r < math.floor(curve_r):
-            grid_r += 10
+        font = painter.font()
+        font.setPixelSize(self.FONT_HEIGHT)
+        painter.setFont(font)

        text_pen = QtGui.QPen(GRAY_COLOR)
-
        grid_pen = QtGui.QPen(GRAY_COLOR.darker(200))
        grid_pen.setWidthF(0)

-        font = painter.font()
-        font.setPixelSize(self.FONT_HEIGHT)
-
+        painter.setPen(grid_pen)
        painter.setBrush(QtCore.Qt.NoBrush)
-        painter.setFont(font)

-        # Calculate samples to display
-        sample_step = math.ceil(self._sample_size / 10.0)
-        min_x = max_x = min_y = max_y = None
-
-        if self._sample_type == SampleType.LINEAR:
-            sample_x_values = self._samples_x_lin
-        else:  # SampleType.LOG
-            sample_x_values = self._samples_x_log
-
-        sample_y_data = []
-        for i, sample_y in enumerate(
-            np.linspace(self._sample_y_min, self._sample_y_max, 11, dtype=np.float32)
-        ):
-            pos_y = sample_y * self.CURVE_SCALE
-            sample_y_data.append((pos_y, sample_y))
-
-            if min_y is None or pos_y < min_y:
-                min_y = pos_y
-            if max_y is None or pos_y > max_y:
-                max_y = pos_y
-
-        sample_x_data = []
-        for i, sample_x in enumerate(sample_x_values):
-            if not (i % sample_step == 0 or i == self._sample_size - 1):
-                continue
-
-            pos_x = self._samples_x_lin[i] * self.CURVE_SCALE
-            sample_x_data.append((pos_x, sample_x))
-
-            if min_x is None or pos_x < min_x:
-                min_x = pos_x
-            if max_x is None or pos_x > max_x:
-                max_x = pos_x
-
-        if min_x is None:
-            min_x = grid_l
-        if max_x is None:
-            max_x = grid_r
-        if min_y is None:
-            min_y = grid_t
-        if max_x is None:
-            max_y = grid_b
-
-        self._sample_rect = QtCore.QRectF(
-            max_x + 5, min_y, 40, len(self._curve_items) * 20
-        )
+        # Draw grid border
+        painter.drawRect(self._curve_rect)

        # Draw grid rows
        y_text_origin = QtGui.QTextOption(QtCore.Qt.AlignRight | QtCore.Qt.AlignVCenter)
        y_text_origin.setWrapMode(QtGui.QTextOption.NoWrap)

-        for pos_y, sample_y in sample_y_data:
-            painter.setPen(grid_pen)
-            painter.drawLine(QtCore.QLineF(min_x, pos_y, max_x, pos_y))
+        for i, y in enumerate(
+            np.linspace(self._y_min, self._y_max, 11, dtype=np.float32)
+        ):
+            p1 = self._curve_tf.map(QtCore.QPointF(self._x_min, y))
+            p2 = self._curve_tf.map(QtCore.QPointF(self._x_max, y))

-            if pos_y > grid_t:
-                label_value = round(sample_y, 2)
+            if self._y_min < y < self._y_max:
+                painter.setPen(grid_pen)
+                painter.drawLine(QtCore.QLineF(p1, p2))
+
+            if y > self._y_min:
+                label_value = round(y, 2)
                if label_value == 0.0:
                    label_value = abs(label_value)

                painter.save()
-                painter.translate(QtCore.QPointF(min_x, pos_y))
+                painter.translate(p1)
                painter.scale(1, -1)
                painter.setPen(text_pen)
                painter.drawText(
@@ -391,28 +443,39 @@ class CurveView(QtWidgets.QGraphicsView):
        x_text_origin = QtGui.QTextOption(QtCore.Qt.AlignLeft | QtCore.Qt.AlignVCenter)
        x_text_origin.setWrapMode(QtGui.QTextOption.NoWrap)

-        for pos_x, sample_x in sample_x_data:
-            painter.setPen(grid_pen)
-            painter.drawLine(QtCore.QLineF(pos_x, min_y, pos_x, max_y))
+        sample_step = math.ceil(self._sample_count / 10.0)

-            if pos_x > grid_l:
+        for i, x in enumerate(self._x_lin):
+            if not (i % sample_step == 0 or i == self._sample_count - 1):
+                continue
+
+            p1 = self._curve_tf.map(QtCore.QPointF(x, self._y_min))
+            p2 = self._curve_tf.map(QtCore.QPointF(x, self._y_max))
+
+            if self._x_min < x < self._x_max:
+                painter.setPen(grid_pen)
+                painter.drawLine(QtCore.QLineF(p1, p2))
+
+            if x > self._x_min:
                label_value = round(
-                    sample_x, 5 if self._sample_type == SampleType.LOG else 2
+                    x if self._sample_type == SampleType.LINEAR else self._x_log[i],
+                    2 if self._sample_type == SampleType.LINEAR else 5,
                )
                if label_value == 0.0:
                    label_value = abs(label_value)

                painter.save()
-                painter.translate(QtCore.QPointF(pos_x, min_y))
+                painter.translate(p1)
                painter.scale(1, -1)
                painter.rotate(90)
                painter.setPen(text_pen)
                painter.drawText(
-                    QtCore.QRect(2.5 + 1, -10, 40, 20), str(label_value), x_text_origin
+                    QtCore.QRectF(2.5 + 1, -10, 40, 20), str(label_value), x_text_origin
                )
                painter.restore()

    def drawForeground(self, painter: QtGui.QPainter, rect: QtCore.QRectF) -> None:
+        """Draw nearest sample point and coordinates."""
        if not self._curve_init:
            return

@@ -436,16 +499,18 @@ class CurveView(QtWidgets.QGraphicsView):
            painter.setBrush(QtGui.QColor(color_name))

            painter.drawEllipse(
-                QtCore.QPointF(
-                    nearest_sample[1] * self.CURVE_SCALE,
-                    nearest_sample[2] * self.CURVE_SCALE,
+                self._curve_tf.map(
+                    QtCore.QPointF(
+                        nearest_sample[1],
+                        nearest_sample[2],
+                    )
                ),
-                1.25,
-                1.25,
+                1.5,
+                1.5,
            )

+            # Draw sample values
            if sample_l is not None:
-                # Draw sample values
                painter.setBrush(QtCore.Qt.NoBrush)

                x_label_value = f"{nearest_sample[0]:.05f}"
@@ -461,27 +526,56 @@ class CurveView(QtWidgets.QGraphicsView):

                if color_name == GRAY_COLOR.name():
                    palette = self.palette()
-                    painter.setPen(palette.color(palette.Text))
+                    painter.setPen(palette.color(palette.ColorRole.Text))
                else:
                    painter.setPen(QtGui.QColor(color_name))
+
                painter.drawText(
                    QtCore.QRectF(5, -20, 35, 10), x_label_value, text_origin
                )
                painter.drawText(
                    QtCore.QRectF(5, -10, 35, 10), y_label_value, text_origin
                )
-
                painter.restore()

+    def _invalidate(self) -> None:
+        """Force repaint of visible region of graphics scene."""
+        self._scene.invalidate(QtCore.QRectF(self.visibleRegion().boundingRect()))
+
    def _update_curves(self) -> None:
+        """
+        Update X-axis samples and rebuild curves from any cached
+        processor.
+        """
        self._update_x_samples()
        if self._prev_cpu_proc is not None:
            self._on_cpu_processor_ready(self._prev_cpu_proc)

+    def _update_x_samples(self):
+        """
+        Update linear and log X-axis samples from input and sample
+        parameters.
+        """
+        self._x_lin = np.linspace(
+            self._input_min, self._input_max, self._sample_count, dtype=np.float32
+        )
+
+        log_min = math.log(max(self.EPSILON, self._input_min))
+        log_max = max(log_min + 0.00001, math.log(self._input_max, self._log_base))
+        self._x_log = np.logspace(
+            log_min, log_max, self._sample_count, base=self._log_base, dtype=np.float32
+        )
+
+        self._x_min = self._x_lin.min()
+        self._x_max = self._x_lin.max()
+
    def _fit(self) -> None:
+        """Fit and center graph."""
        if not self._curve_init:
            return

+        # Use font metrics to calculate text padding, based on estimated maximum
+        # number lengths.
        font = self.font()
        font.setPixelSize(self.FONT_HEIGHT)
        fm = QtGui.QFontMetrics(font)
@@ -503,29 +597,15 @@ class CurveView(QtWidgets.QGraphicsView):

        fit_rect = self._curve_rect.adjusted(-pad_l, -pad_t, pad_r, pad_b)

+        # Fit and center on calculated rectangle
        self.fitInView(fit_rect, QtCore.Qt.KeepAspectRatio)
        self.centerOn(fit_rect.center())
        self.update()

-    def _invalidate(self) -> None:
-        self._scene.invalidate(QtCore.QRectF(self.visibleRegion().boundingRect()))
-
-    def _update_x_samples(self):
-        self._samples_x_lin = np.linspace(
-            self._input_min, self._input_max, self._sample_size, dtype=np.float32
-        )
-        self._samples_x_log = np.logspace(
-            math.log(max(self.LOG_EPSILON, self._input_min)),
-            math.log(max(self.LOG_EPSILON, self._input_max)),
-            self._sample_size,
-            base=self._log_base,
-            dtype=np.float32,
-        )
-
    @QtCore.Slot(ocio.CPUProcessor)
    def _on_cpu_processor_ready(self, cpu_proc: ocio.CPUProcessor) -> None:
        """
-        Update curves from OCIO CPU processor.
+        Update curves from sampled OCIO CPU processor.

        :param cpu_proc: CPU processor of currently viewed transform
        """
@@ -535,12 +615,12 @@ class CurveView(QtWidgets.QGraphicsView):

        # Get input samples
        if self._sample_type == SampleType.LOG:
-            samples = self._samples_x_log
+            x_samples = self._x_log
        else:  # LINEAR
-            samples = self._samples_x_lin
+            x_samples = self._x_lin

        # Interleave samples per channel
-        rgb_samples = np.repeat(samples, 3)
+        rgb_samples = np.repeat(x_samples, 3)

        # Apply processor to samples
        cpu_proc.applyRGB(rgb_samples)
@@ -550,28 +630,21 @@ class CurveView(QtWidgets.QGraphicsView):
        g_samples = rgb_samples[1::3]
        b_samples = rgb_samples[2::3]

-        # Build painter path from sample data
-        if np.array_equal(r_samples, g_samples) and np.array_equal(
-            r_samples, b_samples
+        # Collect sample pairs and min/max Y sample values
+        if np.allclose(r_samples, g_samples, atol=self.EPSILON) and np.allclose(
+            r_samples, b_samples, atol=self.EPSILON
        ):
            palette = self.palette()
-            color_name = palette.color(palette.Text).name()
+            color_name = palette.color(palette.ColorRole.Text).name()

-            self._samples[color_name] = np.dstack((self._samples_x_lin, r_samples))
-            self._sample_y_min = r_samples.min()
-            self._sample_y_max = r_samples.max()
+            self._samples[color_name] = np.stack((self._x_lin, r_samples), axis=-1)

-            curve = QtGui.QPainterPath(
-                QtCore.QPointF(self._samples_x_lin[0], r_samples[0])
-            )
-            curve.reserve(samples.size)
-            for i in range(1, samples.size):
-                curve.lineTo(QtCore.QPointF(self._samples_x_lin[i], r_samples[i]))
-            self._curve_paths[color_name] = curve
+            self._y_min = r_samples.min()
+            self._y_max = r_samples.max()

        else:
-            sample_y_min = None
-            sample_y_max = None
+            y_min = None
+            y_max = None

            for i, (color, channel_samples) in enumerate(
                [
@@ -582,43 +655,71 @@ class CurveView(QtWidgets.QGraphicsView):
            ):
                color_name = color.name()

-                self._samples[color_name] = np.dstack(
-                    (self._samples_x_lin, channel_samples)
+                self._samples[color_name] = np.stack(
+                    (self._x_lin, channel_samples), axis=-1
                )

-                channel_sample_y_min = channel_samples.min()
-                if sample_y_min is None or channel_sample_y_min < sample_y_min:
-                    sample_y_min = channel_sample_y_min
-                channel_sample_y_max = channel_samples.max()
-                if sample_y_max is None or channel_sample_y_max > sample_y_max:
-                    sample_y_max = channel_sample_y_max
+                channel_y_min = channel_samples.min()
+                if y_min is None or channel_y_min < y_min:
+                    y_min = channel_y_min
+                channel_y_max = channel_samples.max()
+                if y_max is None or channel_y_max > y_max:
+                    y_max = channel_y_max

-                curve = QtGui.QPainterPath(
-                    QtCore.QPointF(self._samples_x_lin[0], channel_samples[0])
+            self._y_min = y_min
+            self._y_max = y_max
+
+        # Transform to scale/translate curve so that it fits in a square and
+        # has its origin at (0, 0).
+        curve_tf = QtGui.QTransform()
+        curve_tf.translate(-self._x_min, -self._y_min)
+        curve_tf.scale(
+            self.CURVE_SCALE / (self._x_max - self._x_min),
+            self.CURVE_SCALE / (self._y_max - self._y_min),
+        )
+        self._curve_tf = curve_tf
+        self._curve_tf_inv, ok = curve_tf.inverted()
+
+        # Curve square
+        self._curve_rect = QtCore.QRectF(
+            self._curve_tf.map(QtCore.QPointF(self._x_min, self._y_min)),
+            self._curve_tf.map(QtCore.QPointF(self._x_max, self._y_max)),
+        )
+
+        # Sample box rect
+        self._sample_rect = QtCore.QRectF(
+            self._curve_rect.right() + 5,
+            self._curve_rect.top(),
+            40,
+            len(self._samples) * 20,
+        )
+
+        # Build painter paths that fit in square from sample data
+        for color_name, channel_samples in self._samples.items():
+            curve = QtGui.QPainterPath(
+                self._curve_tf.map(
+                    QtCore.QPointF(channel_samples[0][0], channel_samples[0][1])
                )
-                curve.reserve(samples.size)
-                for j in range(1, samples.size):
-                    curve.lineTo(
-                        QtCore.QPointF(self._samples_x_lin[j], channel_samples[j])
+            )
+            curve.reserve(channel_samples.shape[0])
+            for i in range(1, channel_samples.shape[0]):
+                curve.lineTo(
+                    self._curve_tf.map(
+                        QtCore.QPointF(channel_samples[i][0], channel_samples[i][1])
                    )
-                self._curve_paths[color_name] = curve
-
-            self._sample_y_min = sample_y_min
-            self._sample_y_max = sample_y_max
+                )
+            self._curve_paths[color_name] = curve

        # Add curve(s) to scene
-        self._curve_rect = QtCore.QRectF()
        for color_name, curve in self._curve_paths.items():
            pen = QtGui.QPen()
            pen.setColor(QtGui.QColor(color_name))
-            pen.setWidthF(0)
+            pen.setWidthF(0.5)

            curve_item = self._scene.addPath(
                curve, pen, QtGui.QBrush(QtCore.Qt.NoBrush)
            )
-            curve_item.setScale(self.CURVE_SCALE)
            self._curve_items[color_name] = curve_item
-            self._curve_rect = self._curve_rect.united(curve_item.sceneBoundingRect())

        self._curve_init = True

@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..log_handlers import set_logging_level
 from ..message_router import MessageRouter
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from .inspect.curve_inspector import CurveInspector
 from .inspect import LogInspector, CodeInspector
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..widgets import ItemModelListWidget
 from ..utils import get_glyph_icon
@@ -5,7 +5,7 @@ from dataclasses import dataclass
 from typing import Any, Callable, Optional, Type

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..undo import ConfigSnapshotUndoCommand
@@ -87,7 +87,7 @@ class BaseActiveDisplayViewModel(BaseConfigItemModel):

    def _get_undo_command_type(
        self, column_desc: ColumnDesc
-    ) -> Type[QtWidgets.QUndoCommand]:
+    ) -> Type[QtGui.QUndoCommand]:
        if column_desc == self.ACTIVE:
            # Changing check state of the ACTIVE column has side effects related to
            # display/view order, so a config snapshot is needed to revert the change.
@@ -4,7 +4,7 @@
 from functools import partial
 from typing import Optional

-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets
 import PyOpenColorIO as ocio

 from ..config_cache import ConfigCache
@@ -5,7 +5,7 @@ import copy
 from typing import Any, Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..ref_space_manager import ReferenceSpaceManager
@@ -4,7 +4,7 @@
 from functools import partial
 from typing import Optional

-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..constants import MARGIN_WIDTH
 from ..transform_manager import TransformManager
@@ -47,7 +47,7 @@ class BaseConfigItemParamEdit(QtWidgets.QWidget):

        if self.__has_transforms__:
            self.__has_tabs__ = True
-            no_tf_color = palette.color(palette.Disabled, palette.Text)
+            no_tf_color = palette.color(palette.ColorGroup.Disabled, palette.ColorRole.Text)
            self._from_ref_icon = get_glyph_icon("mdi6.layers-plus")
            self._no_from_ref_icon = get_glyph_icon(
                "mdi6.layers-plus", color=no_tf_color
@@ -6,7 +6,7 @@ from dataclasses import dataclass
 from typing import Any, Optional, Type, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..config_cache import ConfigCache
 from ..transform_manager import TransformManager, TransformAgent
@@ -587,7 +587,7 @@ class BaseConfigItemModel(QtCore.QAbstractTableModel):

    def _get_undo_command_type(
        self, column_desc: ColumnDesc
-    ) -> Type[QtWidgets.QUndoCommand]:
+    ) -> Type[QtGui.QUndoCommand]:
        """
        Support overriding the undo command type used to
        track data changes, per column.
@@ -5,7 +5,7 @@ from pathlib import Path
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtWidgets
+from PySide6 import QtWidgets

 from ..constants import RGB
 from ..widgets import (
@@ -5,7 +5,7 @@ import logging
 from pathlib import Path
 from typing import Any, Optional

-from PySide2 import QtCore
+from PySide6 import QtCore
 import PyOpenColorIO as ocio

 from .config_item_model import ColumnDesc, BaseConfigItemModel
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..config_cache import ConfigCache
 from ..widgets import CallbackComboBox
@@ -34,7 +34,6 @@ class ColorSpaceDelegate(QtWidgets.QStyledItemDelegate):
        editor = CallbackComboBox(
            get_items=ConfigCache.get_color_space_names, editable=True, parent=parent
        )
-        editor.setAutoCompletion(True)
        editor.completer().setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
        return editor

@@ -119,7 +118,6 @@ class RoleDelegate(QtWidgets.QStyledItemDelegate):
            raise NotImplementedError

        widget = CallbackComboBox(get_items=get_items, editable=True, parent=parent)
-        widget.setAutoCompletion(True)
        widget.completer().setCompletionMode(QtWidgets.QCompleter.PopupCompletion)
        return widget

@@ -5,7 +5,7 @@ from dataclasses import dataclass, field
 from typing import Any, Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..config_cache import ConfigCache
 from ..utils import next_name
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..utils import get_glyph_icon
 from .active_display_view_edit import ActiveDisplayViewEdit
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..config_cache import ConfigCache
 from ..utils import get_glyph_icon
@@ -6,7 +6,7 @@ from dataclasses import dataclass, field
 from typing import Any, Optional, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..undo import ConfigSnapshotUndoCommand
@@ -5,7 +5,7 @@ from functools import partial
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtWidgets
+from PySide6 import QtWidgets

 from ..config_cache import ConfigCache
 from ..widgets import CallbackComboBox, TextEdit
@@ -5,7 +5,7 @@ import copy
 from typing import Any, Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..ref_space_manager import ReferenceSpaceManager
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtWidgets
+from PySide6 import QtWidgets

 from ..config_cache import ConfigCache
 from ..utils import get_glyph_icon
@@ -5,7 +5,7 @@ import copy
 from typing import Any, Optional, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..utils import get_glyph_icon
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtGui, QtWidgets
+from PySide6 import QtGui, QtWidgets

 from ..widgets import ItemModelTableWidget
 from .delegates import RoleDelegate
@@ -5,7 +5,7 @@ from dataclasses import dataclass
 from typing import Any

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..config_cache import ConfigCache
 from .config_item_model import ColumnDesc, BaseConfigItemModel
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from ..utils import get_glyph_icon
 from .file_rule_edit import FileRuleEdit
@@ -5,7 +5,7 @@ from functools import partial
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtWidgets
+from PySide6 import QtWidgets

 from ..config_cache import ConfigCache
 from ..widgets import CallbackComboBox, LineEdit
@@ -6,7 +6,7 @@ from dataclasses import dataclass, field
 from typing import Any, Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from .config_item_model import ColumnDesc, BaseConfigItemModel
@@ -5,7 +5,7 @@ from functools import partial
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..config_cache import ConfigCache
 from ..transform_manager import TransformManager
@@ -4,7 +4,7 @@
 from typing import Any, Optional, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..ref_space_manager import ReferenceSpaceManager
@@ -4,7 +4,7 @@
 from functools import partial
 from typing import Optional

-from PySide2 import QtWidgets
+from PySide6 import QtWidgets
 import PyOpenColorIO as ocio

 from ..config_cache import ConfigCache
@@ -5,7 +5,7 @@ import copy
 from typing import Any, Optional, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..utils import get_enum_member, get_glyph_icon
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..config_cache import ConfigCache
 from ..utils import get_glyph_icon
@@ -7,7 +7,7 @@ from dataclasses import dataclass, field
 from typing import Any, Optional, Union

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from ..config_cache import ConfigCache
 from ..undo import ConfigSnapshotUndoCommand
@@ -7,7 +7,7 @@ from pathlib import Path
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from .config_cache import ConfigCache
 from .config_dock import ConfigDock
@@ -10,7 +10,7 @@ from typing import Any, Optional
 from queue import Empty, SimpleQueue

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui, QtWidgets
+from PySide6 import QtCore, QtGui, QtWidgets

 from .utils import config_to_html, processor_to_ctf_html, processor_to_shader_html

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: BSD-3-Clause
 # Copyright Contributors to the OpenColorIO Project.

-from PySide2 import QtCore
+from PySide6 import QtCore


 settings = QtCore.QSettings(
@@ -3,7 +3,7 @@

 from typing import Optional

-from PySide2 import QtGui, QtWidgets
+from PySide6 import QtGui, QtWidgets

 from .constants import (
    BORDER_COLOR_ROLE,
@@ -7,7 +7,7 @@ from functools import partial
 from typing import Callable, Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtGui
+from PySide6 import QtCore, QtGui

 from .utils import get_glyph_icon

@@ -99,12 +99,15 @@ class TransformManager:
        tf_agent.item_tf_changed.connect(partial(cls._on_item_tf_changed, slot))
        cls._tf_subscriptions[slot] = tf_subscription

-        # Trigger immediate update to subscribers
+        # Inform menu subscribers of the menu change
        cls._update_menu_items()
-        cls._on_item_tf_changed(
-            slot,
-            *item_model.get_item_transforms(item_name),
-        )
+
+        # Inform init subscribers of the new subscription
+        for init_callback in cls._tf_subscribers.get(-1, []):
+            init_callback(slot)
+
+        # Trigger immediate update to subscribers of this slot
+        cls._on_item_tf_changed(slot, *item_model.get_item_transforms(item_name))

        # Repaint views for previous and new model
        if prev_item_model is not None:
@@ -206,10 +209,27 @@ class TransformManager:
        menu_callback(cls.get_subscription_menu_items())

    @classmethod
-    def subscribe_to_transforms(cls, slot: int, tf_callback: Callable) -> None:
+    def subscribe_to_transform_subscription_init(cls, init_callback: Callable) -> None:
        """
-        Subscribe to transform and item name updates at the given slot
-        number.
+        Subscribe to transform subscription initialization on all slots.
+
+        :param init_callback: Transform subscription initialization
+            callback, which will be called whenever a new transform
+            subscription is initialized with the subscription slot
+            number.
+        """
+        cls._tf_subscribers[-1].append(init_callback)
+
+        # Trigger immediate update to init subscriber if a transform subscription
+        # exists.
+        for slot, tf_subscription in cls._tf_subscriptions.items():
+            init_callback(slot)
+            break
+
+    @classmethod
+    def subscribe_to_transforms_at(cls, slot: int, tf_callback: Callable) -> None:
+        """
+        Subscribe to transform updates at the given slot number.

        :param slot: Subscription slot number
        :param tf_callback: Transform callback, which will be called
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..widgets import EnumComboBox, FloatEdit, FloatEditArray
 from .transform_edit import BaseTransformEdit
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..widgets import ComboBox
 from .transform_edit import BaseTransformEdit
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..constants import RGB
 from ..widgets import EnumComboBox, FloatEdit, FloatEditArray
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..config_cache import ConfigCache
 from ..widgets import CheckBox, CallbackComboBox
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..config_cache import ConfigCache
 from ..utils import SignalsBlocked
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..constants import RGBA
 from ..widgets import EnumComboBox, FloatEditArray
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..constants import RGBA
 from ..widgets import EnumComboBox, FloatEditArray
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..widgets import EnumComboBox, FloatEdit
 from .transform_edit import BaseTransformEdit
@@ -5,7 +5,7 @@ import os
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore
+from PySide6 import QtCore

 from ..widgets import EnumComboBox, LineEdit
 from .transform_edit import BaseTransformEdit
@@ -4,7 +4,7 @@
 from typing import Optional

 import PyOpenColorIO as ocio
-from PySide2 import QtCore, QtWidgets
+from PySide6 import QtCore, QtWidgets

 from ..widgets import EnumComboBox, FloatEditArray, ExpandingStackedWidget
 from .transform_edit import BaseTransformEdit
--- a/Show More
+++ b/Show More