Python API: add mathutils.Color functions to convert color spaces

Between scene linear and sRGB, XYZ, linear Rec.709 and ACES2065-1.

And add some clarifications about color spaces in the docs.

Fixes T98267

Ref T68926

Differential Revision: https://developer.blender.org/D14989

4 files changed, 48 insertions, 6 deletions

diff --git a/source/blender/imbuf/IMB_colormanagement.h b/source/blender/imbuf/IMB_colormanagement.h
index 1f0ed4cafbe..94036da9d22 100644
--- a/source/blender/imbuf/IMB_colormanagement.h
+++ b/source/blender/imbuf/IMB_colormanagement.h
@@ -72,8 +72,16 @@ BLI_INLINE float IMB_colormanagement_get_luminance(const float rgb[3]);
  * Byte equivalent of #IMB_colormanagement_get_luminance().
  */
 BLI_INLINE unsigned char IMB_colormanagement_get_luminance_byte(const unsigned char[3]);
+
+/**
+ * Conversion between scene linear and other color spaces.
+ */
 BLI_INLINE void IMB_colormanagement_xyz_to_rgb(float rgb[3], const float xyz[3]);
 BLI_INLINE void IMB_colormanagement_rgb_to_xyz(float xyz[3], const float rgb[3]);
+BLI_INLINE void IMB_colormanagement_rec709_to_rgb(float rgb[3], const float rec709[3]);
+BLI_INLINE void IMB_colormanagement_rgb_to_rec709(float rec709[3], const float rgb[3]);
+BLI_INLINE void IMB_colormanagement_aces_to_rgb(float rgb[3], const float aces[3]);
+BLI_INLINE void IMB_colormanagement_rgb_to_aces(float aces[3], const float rgb[3]);
 const float *IMB_colormanagement_get_xyz_to_rgb(void);
 
 /** \} */
diff --git a/source/blender/imbuf/intern/IMB_colormanagement_intern.h b/source/blender/imbuf/intern/IMB_colormanagement_intern.h
index c89b15480a2..fd70c633f83 100644
--- a/source/blender/imbuf/intern/IMB_colormanagement_intern.h
+++ b/source/blender/imbuf/intern/IMB_colormanagement_intern.h
@@ -20,6 +20,10 @@ struct OCIO_ConstCPUProcessorRcPtr;
 extern float imbuf_luma_coefficients[3];
 extern float imbuf_xyz_to_rgb[3][3];
 extern float imbuf_rgb_to_xyz[3][3];
+extern float imbuf_xyz_to_aces[3][3];
+extern float imbuf_aces_to_xyz[3][3];
+extern float imbuf_xyz_to_rec709[3][3];
+extern float imbuf_rec709_to_xyz[3][3];
 
 #define MAX_COLORSPACE_NAME 64
 #define MAX_COLORSPACE_DESCRIPTION 512
diff --git a/source/blender/imbuf/intern/colormanagement.c b/source/blender/imbuf/intern/colormanagement.c
index 95e2d36891a..f189614e61c 100644
--- a/source/blender/imbuf/intern/colormanagement.c
+++ b/source/blender/imbuf/intern/colormanagement.c
@@ -75,8 +75,10 @@ static int global_tot_looks = 0;
 float imbuf_luma_coefficients[3] = {0.0f};
 float imbuf_xyz_to_rgb[3][3] = {{0.0f}};
 float imbuf_rgb_to_xyz[3][3] = {{0.0f}};
-static float imbuf_xyz_to_linear_srgb[3][3] = {{0.0f}};
-static float imbuf_linear_srgb_to_xyz[3][3] = {{0.0f}};
+float imbuf_xyz_to_rec709[3][3] = {{0.0f}};
+float imbuf_rec709_to_xyz[3][3] = {{0.0f}};
+float imbuf_xyz_to_aces[3][3] = {{0.0f}};
+float imbuf_aces_to_xyz[3][3] = {{0.0f}};
 
 /* lock used by pre-cached processors getters, so processor wouldn't
  * be created several times
@@ -573,10 +575,14 @@ static void colormanage_load_config(OCIO_ConstConfigRcPtr *config)
 
   /* Load luminance coefficients. */
   OCIO_configGetDefaultLumaCoefs(config, imbuf_luma_coefficients);
+
+  /* Load standard color spaces. */
   OCIO_configGetXYZtoRGB(config, imbuf_xyz_to_rgb);
   invert_m3_m3(imbuf_rgb_to_xyz, imbuf_xyz_to_rgb);
-  copy_m3_m3(imbuf_xyz_to_linear_srgb, OCIO_XYZ_TO_LINEAR_SRGB);
-  invert_m3_m3(imbuf_linear_srgb_to_xyz, imbuf_xyz_to_linear_srgb);
+  copy_m3_m3(imbuf_xyz_to_rec709, OCIO_XYZ_TO_REC709);
+  invert_m3_m3(imbuf_rec709_to_xyz, imbuf_xyz_to_rec709);
+  copy_m3_m3(imbuf_aces_to_xyz, OCIO_ACES_TO_XYZ);
+  invert_m3_m3(imbuf_xyz_to_aces, imbuf_aces_to_xyz);
 }
 
 static void colormanage_free_config(void)
@@ -2370,14 +2376,14 @@ void IMB_colormanagement_color_picking_to_scene_linear_v3(float pixel[3])
 void IMB_colormanagement_scene_linear_to_srgb_v3(float pixel[3])
 {
   mul_m3_v3(imbuf_rgb_to_xyz, pixel);
-  mul_m3_v3(imbuf_xyz_to_linear_srgb, pixel);
+  mul_m3_v3(imbuf_xyz_to_rec709, pixel);
   linearrgb_to_srgb_v3_v3(pixel, pixel);
 }
 
 void IMB_colormanagement_srgb_to_scene_linear_v3(float pixel[3])
 {
   srgb_to_linearrgb_v3_v3(pixel, pixel);
-  mul_m3_v3(imbuf_linear_srgb_to_xyz, pixel);
+  mul_m3_v3(imbuf_rec709_to_xyz, pixel);
   mul_m3_v3(imbuf_xyz_to_rgb, pixel);
 }
 
diff --git a/source/blender/imbuf/intern/colormanagement_inline.c b/source/blender/imbuf/intern/colormanagement_inline.c
index 411cf9af802..4c632da1520 100644
--- a/source/blender/imbuf/intern/colormanagement_inline.c
+++ b/source/blender/imbuf/intern/colormanagement_inline.c
@@ -37,4 +37,28 @@ void IMB_colormanagement_rgb_to_xyz(float xyz[3], const float rgb[3])
   mul_v3_m3v3(xyz, imbuf_rgb_to_xyz, rgb);
 }
 
+void IMB_colormanagement_rec709_to_rgb(float rgb[3], const float rec709[3])
+{
+  mul_v3_m3v3(rgb, imbuf_rec709_to_xyz, rec709);
+  mul_v3_m3v3(rgb, imbuf_xyz_to_rgb, rgb);
+}
+
+void IMB_colormanagement_rgb_to_rec709(float rec709[3], const float rgb[3])
+{
+  mul_v3_m3v3(rec709, imbuf_rgb_to_xyz, rgb);
+  mul_v3_m3v3(rec709, imbuf_xyz_to_rec709, rec709);
+}
+
+void IMB_colormanagement_aces_to_rgb(float rgb[3], const float aces[3])
+{
+  mul_v3_m3v3(rgb, imbuf_aces_to_xyz, aces);
+  mul_v3_m3v3(rgb, imbuf_xyz_to_rgb, rgb);
+}
+
+void IMB_colormanagement_rgb_to_aces(float aces[3], const float rgb[3])
+{
+  mul_v3_m3v3(aces, imbuf_rgb_to_xyz, rgb);
+  mul_v3_m3v3(aces, imbuf_xyz_to_aces, aces);
+}
+
 #endif /* __IMB_COLORMANAGEMENT_INLINE_H__ */