Implement support for "Kirk (2019)" "Yrg" colourspace.

Author: KelSolaar

BIBLIOGRAPHY.bib

@@ -917,6 +917,14 @@ Ragoo and Farup (2021) Optimised IPT Colourspace
     >>> colour.XYZ_to_IPT_Ragoo2021([0.20654008, 0.12197225, 0.05136952])
     array([ 0.42248243,  0.2910514 ,  0.20410663])
 
+Yrg Colourspace - Kirk (2019)
+*****************************
+
+.. code-block:: python
+
+    >>> colour.XYZ_to_Yrg([0.20654008, 0.12197225, 0.05136952])
+    array([ 0.13137801,  0.49037645,  0.37777388])
+
 Y'CbCr Colour Encoding
 **********************
 

README.rst

@@ -339,9 +339,11 @@
     XYZ_to_sRGB,
     XYZ_to_xy,
     XYZ_to_xyY,
+    XYZ_to_Yrg,
     YCbCr_to_RGB,
     YCoCg_to_RGB,
     YcCbcCrc_to_RGB,
+    Yrg_to_XYZ,
     cctf_decoding,
     cctf_encoding,
     chromatically_adapted_primaries,
@@ -763,9 +765,11 @@ def __getattr__(self, attribute) -> Any:
     "XYZ_to_sRGB",
     "XYZ_to_xy",
     "XYZ_to_xyY",
+    "XYZ_to_Yrg",
     "YCbCr_to_RGB",
     "YCoCg_to_RGB",
     "YcCbcCrc_to_RGB",
+    "Yrg_to_XYZ",
     "cctf_decoding",
     "cctf_encoding",
     "chromatically_adapted_primaries",

colour/__init__.py

@@ -130,9 +130,11 @@
     XYZ_to_sRGB,
     XYZ_to_xy,
     XYZ_to_xyY,
+    XYZ_to_Yrg,
     YCbCr_to_RGB,
     YCoCg_to_RGB,
     YcCbcCrc_to_RGB,
+    Yrg_to_XYZ,
     cctf_decoding,
     cctf_encoding,
     hdr_CIELab_to_XYZ,
@@ -753,6 +755,8 @@ def mired_to_CCT_D_uv(mired: ArrayLike) -> NDArrayFloat:
     ("Oklab", "CIE XYZ", Oklab_to_XYZ),
     ("CIE XYZ", "ProLab", XYZ_to_ProLab),
     ("ProLab", "CIE XYZ", ProLab_to_XYZ),
+    ("CIE XYZ", "Yrg", XYZ_to_Yrg),
+    ("Yrg", "CIE XYZ", Yrg_to_XYZ),
     # RGB Colour Models
     (
         "CIE XYZ",

colour/graph/conversion.py

@@ -97,6 +97,7 @@
 from .osa_ucs import XYZ_to_OSA_UCS, OSA_UCS_to_XYZ
 from .prolab import XYZ_to_ProLab, ProLab_to_XYZ
 from .ragoo2021 import XYZ_to_IPT_Ragoo2021, IPT_Ragoo2021_to_XYZ
+from .yrg import LMS_to_Yrg, Yrg_to_LMS, XYZ_to_Yrg, Yrg_to_XYZ
 from .datasets import (
     DATA_MACADAM_1942_ELLIPSES,
     CCS_ILLUMINANT_POINTER_GAMUT,
@@ -483,6 +484,12 @@
     "XYZ_to_IPT_Ragoo2021",
     "IPT_Ragoo2021_to_XYZ",
 ]
+__all__ += [
+    "LMS_to_Yrg",
+    "Yrg_to_LMS",
+    "XYZ_to_Yrg",
+    "Yrg_to_XYZ",
+]
 __all__ += [
     "HDR_IPT_METHODS",
     "XYZ_to_hdr_IPT",

colour/models/__init__.py

@@ -82,6 +82,7 @@
     "Oklab",
     "hdr-CIELAB",
     "hdr-IPT",
+    "Yrg",
 )
 if is_documentation_building():  # pragma: no cover
     COLOURSPACE_MODELS = DocstringTuple(COLOURSPACE_MODELS)
@@ -117,6 +118,7 @@
         "Oklab": ("$L$", "$a$", "$b$"),
         "hdr-CIELAB": ("L hdr", "a hdr", "b hdr"),
         "hdr-IPT": ("I hdr", "P hdr", "T hdr"),
+        "Yrg": ("Y", "r", "g"),
     }
 )
 """Colourspace models labels mapping."""
@@ -152,6 +154,7 @@
         "Oklab": np.array([1, 1, 1]),
         "hdr-CIELAB": np.array([100, 100, 100]),
         "hdr-IPT": np.array([100, 100, 100]),
+        "Yrg": np.array([1, 1, 1]),
     }
 )
 """Colourspace models domain-range scale **'1'** to **'Reference'** mapping."""