ProPhotoRGB builtin transforms

docs/guides/authoring/colorspaces.rst

@@ -579,7 +579,7 @@ its transforms.
 
       - !<ColorSpace>
         name: sRGB
-        family: 
+        family:
         description: |
           sRGB monitor (piecewise EOTF)
         isdata: false
@@ -589,3 +589,74 @@ its transforms.
           children:
             - !<BuiltinTransform> {style: "DISPLAY - CIE-XYZ-D65_to_sRGB"}
             - !<RangeTransform> {min_in_value: 0., min_out_value: 0., max_in_value: 1., max_out_value: 1.}
+
+
+Using Builtin Transforms
+-------------------------
+
+OCIO provides a set of builtin transforms that implement common color space conversions. These
+transforms are pre-defined and maintained as part of the OCIO library, ensuring consistent
+behavior across applications.
+
+To use a builtin transform, specify it with the ``!<BuiltinTransform>`` tag and provide the
+``style`` parameter with the name of the desired transform. For example:
+
+.. code-block:: yaml
+
+    - !<ColorSpace>
+      name: ProPhoto RGB
+      description: |
+        ProPhoto RGB / ROMM RGB (D50 white point, gamma 1.8 encoded)
+      from_scene_reference: !<BuiltinTransform> {style: "ACES2065-1_to_PROPHOTO-RGB-ENCODED"}
+
+The available builtin transform styles can be queried programmatically using the
+BuiltinTransformRegistry API, or by using the ``ociocheck`` command-line tool with the
+``--list-builtins`` option.
+
+ProPhotoRGB / ROMM RGB Builtin Transforms
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+ProPhotoRGB (also known as ROMM RGB) is a wide-gamut color space specified in ANSI/I3A
+IT10.7666:2003. OCIO provides builtin transforms to convert between ProPhotoRGB and ACES2065-1.
+
+The following builtin transform styles are available:
+
+Native ROMM RGB (Gamma 1.8):
+  * ``PROPHOTO-RGB_to_ACES2065-1`` - Linear ProPhoto RGB to ACES2065-1
+  * ``PROPHOTO-RGB-ENCODED_to_ACES2065-1`` - Gamma 1.8 encoded ProPhoto RGB to ACES2065-1
+  * ``ACES2065-1_to_PROPHOTO-RGB`` - ACES2065-1 to linear ProPhoto RGB
+  * ``ACES2065-1_to_PROPHOTO-RGB-ENCODED`` - ACES2065-1 to gamma 1.8 encoded ProPhoto RGB
+
+ProPhoto RGB with sRGB Gamma:
+  * ``PROPHOTO-RGB-SRGB-GAMMA_to_ACES2065-1`` - sRGB gamma encoded ProPhoto RGB to ACES2065-1
+  * ``ACES2065-1_to_PROPHOTO-RGB-SRGB-GAMMA`` - ACES2065-1 to sRGB gamma encoded ProPhoto RGB
+
+Example using ProPhotoRGB with gamma 1.8 encoding:
+
+.. code-block:: yaml
+
+    colorspaces:
+      - !<ColorSpace>
+        name: ProPhoto-RGB-Gamma1.8
+        family: Input/ProPhotoRGB
+        description: |
+          ProPhoto RGB / ROMM RGB with native gamma 1.8 encoding
+        isdata: false
+        categories: [ file-io, working-space ]
+        encoding: sdr-video
+        to_scene_reference: !<BuiltinTransform> {style: "PROPHOTO-RGB-ENCODED_to_ACES2065-1"}
+
+Example using ProPhotoRGB with sRGB gamma encoding (common in Adobe workflows):
+
+.. code-block:: yaml
+
+    colorspaces:
+      - !<ColorSpace>
+        name: ProPhoto-RGB-sRGB-Gamma
+        family: Input/ProPhotoRGB
+        description: |
+          ProPhoto RGB with sRGB transfer function (Adobe variant)
+        isdata: false
+        categories: [ file-io, working-space ]
+        encoding: sdr-video
+        to_scene_reference: !<BuiltinTransform> {style: "PROPHOTO-RGB-SRGB-GAMMA_to_ACES2065-1"}

docs/releases/ocio_2_5.rst

@@ -315,6 +315,44 @@ around the origin to pass negative values rather than clamp them:
 * ``DISPLAY - CIE-XYZ-D65_to_sRGB - MIRROR NEGS``
 * ``DISPLAY - CIE-XYZ-D65_to_G2.6-P3-D65 - MIRROR NEGS``
 
+ProPhotoRGB / ROMM RGB Built-in Transforms
+*******************************************
+
+For Config Authors
+++++++++++++++++++
+
+ProPhotoRGB (also known as ROMM RGB, Reference Output Medium Metric RGB) is now supported as
+a set of builtin transforms. ProPhotoRGB is specified in the ANSI/I3A IT10.7666:2003 standard
+and is a wide-gamut color space commonly used in photography workflows.
+
+The ProPhotoRGB color primaries are combined with the ACES2065-1 AP0 reference connection
+space using Bradford chromatic adaptation to convert between the D50 white point (ProPhotoRGB)
+and D60 white point (ACES AP0).
+
+Two transfer function variants are provided:
+
+Native ROMM RGB (Gamma 1.8)
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The following styles implement the standard ROMM RGB gamma 1.8 piecewise transfer function:
+
+* ``PROPHOTO-RGB_to_ACES2065-1`` - Convert ProPhoto RGB (linear) to ACES2065-1
+* ``PROPHOTO-RGB-ENCODED_to_ACES2065-1`` - Convert ProPhoto RGB (gamma 1.8 encoded) to ACES2065-1
+* ``ACES2065-1_to_PROPHOTO-RGB`` - Convert ACES2065-1 to ProPhoto RGB (linear)
+* ``ACES2065-1_to_PROPHOTO-RGB-ENCODED`` - Convert ACES2065-1 to ProPhoto RGB (gamma 1.8 encoded)
+
+The gamma 1.8 curve is a piecewise function with a linear segment below 0.001953 (slope of 16)
+and a power function above that breakpoint.
+
+ProPhoto RGB with sRGB Gamma
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+The following styles use ProPhotoRGB primaries but with the sRGB transfer function (gamma 2.4,
+offset 0.055). This variant is commonly used in Adobe applications and other photography workflows:
+
+* ``PROPHOTO-RGB-SRGB-GAMMA_to_ACES2065-1`` - Convert ProPhoto RGB (sRGB gamma) to ACES2065-1
+* ``ACES2065-1_to_PROPHOTO-RGB-SRGB-GAMMA`` - Convert ACES2065-1 to ProPhoto RGB (sRGB gamma)
+
 
 Release Notes
 =============

src/OpenColorIO/CMakeLists.txt

@@ -166,6 +166,7 @@ set(SOURCES
     transforms/builtins/CanonCameras.cpp
     transforms/builtins/Displays.cpp
     transforms/builtins/PanasonicCameras.cpp
+    transforms/builtins/ProPhotoRGB.cpp
     transforms/builtins/RedCameras.cpp
     transforms/builtins/SonyCameras.cpp
     transforms/BuiltinTransform.cpp