Remove ability to pass illuminant in "CIE XYZ" to "CIE xyY" related t…

…ransformations.

This is not a CIE recommendation and the choice of what to when null tristimulus values are passed should be given to the user.

colour/characterisation/datasets/colour_checkers/chromaticity_coordinates.py

@@ -464,10 +464,7 @@ class ColourChecker(
 DATA_TE226_V2: dict = dict(
     zip(
         tuple(DATA_TE226_V2_CIE_XYZ.keys()),
-        XYZ_to_xyY(
-            list(DATA_TE226_V2_CIE_XYZ.values()),
-            CCS_ILLUMINANTS["CIE 1931 2 Degree Standard Observer"]["D65"],
-        ),
+        XYZ_to_xyY(list(DATA_TE226_V2_CIE_XYZ.values())),
     )
 )
 
@@ -481,7 +478,7 @@ class ColourChecker(
 )
 """
 Reference data from *TE226 V2*. Transparent color rendition test chart
-for HDTV cameras, in addition to known colors from “ColorChecker”, the test
+for HDTV cameras, in addition to known colors from "ColorChecker", the test
 chart contains colors which are critical in reproduction.
 """
 

colour/examples/models/examples_models.py

@@ -24,14 +24,6 @@
 
 print("\n")
 
-message_box("Using an alternative illuminant.")
-print(
-    colour.XYZ_to_xyY(
-        np.array([0.00000000, 0.00000000, 0.00000000]),
-        colour.CCS_ILLUMINANTS["CIE 1931 2 Degree Standard Observer"]["ACES"],
-    )
-)
-
 print("\n")
 
 xyY = np.array([0.26414772, 0.37770001, 0.10080000])

colour/graph/tests/test_conversion.py

@@ -138,9 +138,9 @@ def test_convert_direct_keyword_argument_passing(self):
         ]
         np.testing.assert_array_almost_equal(
             convert(
-                a, "CIE XYZ", "CIE xyY", XYZ_to_xyY={"illuminant": illuminant}
+                a, "CIE XYZ", "CIE UVW", XYZ_to_UVW={"illuminant": illuminant}
             ),
-            convert(a, "CIE XYZ", "CIE xyY", illuminant=illuminant),
+            convert(a, "CIE XYZ", "CIE UVW", illuminant=illuminant),
             decimal=7,
         )
 

colour/models/cie_xyy.py

@@ -13,10 +13,9 @@
 
 References
 ----------
--   :cite:`Lindbloom2003e` : Lindbloom, B. (2003). XYZ to xyY. Retrieved
-    February 24, 2014, from http://www.brucelindbloom.com/Eqn_XYZ_to_xyY.html
--   :cite:`Lindbloom2009d` : Lindbloom, B. (2009). xyY to XYZ. Retrieved
-    February 24, 2014, from http://www.brucelindbloom.com/Eqn_xyY_to_XYZ.html
+-   :cite:`CIETC1-482004h` : CIE TC 1-48. (2004). CIE 015:2004 Colorimetry,
+    3rd Edition. In CIE 015:2004 Colorimetry, 3rd Edition. Commission
+    Internationale de l'Eclairage. ISBN:978-3-901906-33-6
 -   :cite:`Wikipedia2005` : Wikipedia. (2005). CIE 1931 color space. Retrieved
     February 24, 2014, from http://en.wikipedia.org/wiki/CIE_1931_color_space
 """
@@ -25,7 +24,6 @@
 
 import numpy as np
 
-from colour.colorimetry import CCS_ILLUMINANTS
 from colour.hints import ArrayLike, NDArrayFloat
 from colour.utilities import (
     as_float_array,
@@ -55,22 +53,14 @@
 ]
 
 
-def XYZ_to_xyY(
-    XYZ: ArrayLike,
-    illuminant: ArrayLike = CCS_ILLUMINANTS[
-        "CIE 1931 2 Degree Standard Observer"
-    ]["D65"],
-) -> NDArrayFloat:
+def XYZ_to_xyY(XYZ: ArrayLike) -> NDArrayFloat:
     """
-    Convert from *CIE XYZ* tristimulus values to *CIE xyY* colourspace and
-    reference *illuminant*.
+    Convert from *CIE XYZ* tristimulus values to *CIE xyY* colourspace.
 
     Parameters
     ----------
     XYZ
         *CIE XYZ* tristimulus values.
-    illuminant
-        Reference *illuminant* chromaticity coordinates.
 
     Returns
     -------
@@ -93,7 +83,7 @@ def XYZ_to_xyY(
 
     References
     ----------
-    :cite:`Lindbloom2003e`, :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------
@@ -103,12 +93,11 @@ def XYZ_to_xyY(
     """
 
     XYZ = to_domain_1(XYZ)
-    xy_w = as_float_array(illuminant)
 
     X, Y, Z = tsplit(XYZ)
 
     xyY = zeros(XYZ.shape)
-    xyY[..., 0:2] = xy_w
+    xyY[..., 0:2] = 0
 
     m_xyY = ~np.all(XYZ == 0, axis=-1)
     X_Y_Z = (X + Y + Z)[m_xyY]
@@ -156,7 +145,7 @@ def xyY_to_XYZ(xyY: ArrayLike) -> NDArrayFloat:
 
     References
     ----------
-    :cite:`Lindbloom2009d`, :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------
@@ -210,7 +199,7 @@ def xyY_to_xy(xyY: ArrayLike) -> NDArrayFloat:
 
     References
     ----------
-    :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------
@@ -277,7 +266,7 @@ def xy_to_xyY(xy: ArrayLike, Y: float = 1) -> NDArrayFloat:
 
     References
     ----------
-    :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------
@@ -307,12 +296,7 @@ def xy_to_xyY(xy: ArrayLike, Y: float = 1) -> NDArrayFloat:
     return from_range_1(xyY, np.array([1, 1, 100]))
 
 
-def XYZ_to_xy(
-    XYZ: ArrayLike,
-    illuminant: ArrayLike = CCS_ILLUMINANTS[
-        "CIE 1931 2 Degree Standard Observer"
-    ]["D65"],
-) -> NDArrayFloat:
+def XYZ_to_xy(XYZ: ArrayLike) -> NDArrayFloat:
     """
     Return the *CIE xy* chromaticity coordinates from given *CIE XYZ*
     tristimulus values.
@@ -321,8 +305,6 @@ def XYZ_to_xy(
     ----------
     XYZ
         *CIE XYZ* tristimulus values.
-    illuminant
-        Reference *illuminant* chromaticity coordinates.
 
     Returns
     -------
@@ -339,7 +321,7 @@ def XYZ_to_xy(
 
     References
     ----------
-    :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------
@@ -348,7 +330,7 @@ def XYZ_to_xy(
     array([ 0.5436955...,  0.3210794...])
     """
 
-    return xyY_to_xy(XYZ_to_xyY(XYZ, illuminant))
+    return xyY_to_xy(XYZ_to_xyY(XYZ))
 
 
 def xy_to_XYZ(xy: ArrayLike) -> NDArrayFloat:
@@ -382,7 +364,7 @@ def xy_to_XYZ(xy: ArrayLike) -> NDArrayFloat:
 
     References
     ----------
-    :cite:`Wikipedia2005`
+    :cite:`CIETC1-482004h`, :cite:`Wikipedia2005`
 
     Examples
     --------

colour/models/tests/test_cie_xyy.py

@@ -78,7 +78,7 @@ def test_XYZ_to_xyY(self):
             np.array(
                 [
                     [0.54369557, 0.32107944, 0.12197225],
-                    [0.31270000, 0.32900000, 0.00000000],
+                    [0.00000000, 0.00000000, 0.00000000],
                     [0.00000000, 1.00000000, 1.00000000],
                 ]
             ),
@@ -92,26 +92,15 @@ def test_n_dimensional_XYZ_to_xyY(self):
         """
 
         XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
-        illuminant = np.array([0.31270, 0.32900])
-        xyY = XYZ_to_xyY(XYZ, illuminant)
+        xyY = XYZ_to_xyY(XYZ)
 
         XYZ = np.tile(XYZ, (6, 1))
         xyY = np.tile(xyY, (6, 1))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xyY(XYZ, illuminant), xyY, decimal=7
-        )
-
-        illuminant = np.tile(illuminant, (6, 1))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xyY(XYZ, illuminant), xyY, decimal=7
-        )
+        np.testing.assert_array_almost_equal(XYZ_to_xyY(XYZ), xyY, decimal=7)
 
         XYZ = np.reshape(XYZ, (2, 3, 3))
-        illuminant = np.reshape(illuminant, (2, 3, 2))
         xyY = np.reshape(xyY, (2, 3, 3))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xyY(XYZ, illuminant), xyY, decimal=7
-        )
+        np.testing.assert_array_almost_equal(XYZ_to_xyY(XYZ), xyY, decimal=7)
 
     def test_domain_range_scale_XYZ_to_xyY(self):
         """
@@ -141,7 +130,7 @@ def test_nan_XYZ_to_xyY(self):
 
         cases = [-1.0, 0.0, 1.0, -np.inf, np.inf, np.nan]
         cases = np.array(list(set(product(cases, repeat=3))))
-        XYZ_to_xyY(cases, cases[..., 0:2])
+        XYZ_to_xyY(cases)
 
 
 class TestxyY_to_XYZ(unittest.TestCase):
@@ -446,7 +435,7 @@ def test_XYZ_to_xy(self):
 
         np.testing.assert_array_almost_equal(
             XYZ_to_xy(np.array([0.00000000, 0.00000000, 0.00000000])),
-            np.array([0.31270000, 0.32900000]),
+            np.array([0.00000000, 0.00000000]),
             decimal=7,
         )
 
@@ -457,26 +446,15 @@ def test_n_dimensional_XYZ_to_xy(self):
         """
 
         XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
-        illuminant = np.array([0.31270, 0.32900])
-        xy = XYZ_to_xy(XYZ, illuminant)
+        xy = XYZ_to_xy(XYZ)
 
         XYZ = np.tile(XYZ, (6, 1))
         xy = np.tile(xy, (6, 1))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xy(XYZ, illuminant), xy, decimal=7
-        )
-
-        illuminant = np.tile(illuminant, (6, 1))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xy(XYZ, illuminant), xy, decimal=7
-        )
+        np.testing.assert_array_almost_equal(XYZ_to_xy(XYZ), xy, decimal=7)
 
         XYZ = np.reshape(XYZ, (2, 3, 3))
-        illuminant = np.reshape(xy, (2, 3, 2))
         xy = np.reshape(xy, (2, 3, 2))
-        np.testing.assert_array_almost_equal(
-            XYZ_to_xy(XYZ, illuminant), xy, decimal=7
-        )
+        np.testing.assert_array_almost_equal(XYZ_to_xy(XYZ), xy, decimal=7)
 
     def test_domain_range_scale_XYZ_to_xy(self):
         """
@@ -502,7 +480,7 @@ def test_nan_XYZ_to_xy(self):
 
         cases = [-1.0, 0.0, 1.0, -np.inf, np.inf, np.nan]
         cases = np.array(list(set(product(cases, repeat=3))))
-        XYZ_to_xy(cases, cases[..., 0:2])
+        XYZ_to_xy(cases)
 
 
 class Testxy_to_XYZ(unittest.TestCase):

colour/plotting/diagrams.py

@@ -175,7 +175,7 @@ def plot_spectral_locus(
 
     labels = ()
     if method == "cie 1931":
-        ij = XYZ_to_xy(cmfs.values, illuminant)
+        ij = XYZ_to_xy(cmfs.values)
         labels = optional(
             spectral_locus_labels,
             (
@@ -452,7 +452,7 @@ def plot_chromaticity_diagram_colours(
     illuminant = CONSTANTS_COLOUR_STYLE.colour.colourspace.whitepoint
 
     if method == "cie 1931":
-        spectral_locus = XYZ_to_xy(cmfs.values, illuminant)
+        spectral_locus = XYZ_to_xy(cmfs.values)
     elif method == "cie 1960 ucs":
         spectral_locus = UCS_to_uv(XYZ_to_UCS(cmfs.values))
     elif method == "cie 1976 ucs":

colour/plotting/models.py

@@ -335,13 +335,15 @@ def plot_pointer_gamut(
 
     if method == "cie 1931":
 
-        def XYZ_to_ij(XYZ: NDArrayFloat, *args: Any) -> NDArrayFloat:
+        def XYZ_to_ij(
+            XYZ: NDArrayFloat, *args: Any  # noqa: ARG001
+        ) -> NDArrayFloat:
             """
             Convert given *CIE XYZ* tristimulus values to *ij* chromaticity
             coordinates.
             """
 
-            return XYZ_to_xy(XYZ, *args)
+            return XYZ_to_xy(XYZ)
 
         def xy_to_ij(xy: NDArrayFloat) -> NDArrayFloat:
             """
@@ -1062,7 +1064,7 @@ def plot_RGB_chromaticities_in_chromaticity_diagram(
     XYZ = RGB_to_XYZ(RGB, colourspace)
 
     if method == "cie 1931":
-        ij = XYZ_to_xy(XYZ, colourspace.whitepoint)
+        ij = XYZ_to_xy(XYZ)
 
     elif method == "cie 1960 ucs":
         ij = UCS_to_uv(XYZ_to_UCS(XYZ))