Add is_within_visible_xy implementation

colour/volume/spectrum.py

@@ -38,6 +38,7 @@
     Literal,
     NDArrayFloat,
 )
+from colour.models.cie_xyy import XYZ_to_xy
 from colour.utilities import (
     CACHE_REGISTRY,
     is_caching_enabled,
@@ -393,14 +394,20 @@ def is_within_visible_spectrum(
     **kwargs: Any,
 ) -> NDArrayFloat:
     """
-    Return whether given *CIE XYZ* tristimulus values are within the visible
-    spectrum volume, i.e. *Rösch-MacAdam* colour solid, for given colour
-    matching functions and illuminant.
+    Return whether given *CIE XYZ* tristimulus values or *CIE xy* chromaticity
+    values are within the visible spectrum volume, i.e. *Rösch-MacAdam* colour
+    solid, for given colour matching functions and illuminant.
+
+    For the brightness invariant *CIE xy* check, the limit is determined by the
+    spectral locus and "line of purples" depending on the precision of the
+    spectral arguments.
 
     Parameters
     ----------
     XYZ
-        *CIE XYZ* tristimulus values.
+        *CIE XYZ* or xy tristimulus values. xy chromaticity mode will be
+        selected if the size of the last dimension is 2. i.e. if XYZ.shape[-1]
+        == 2
     cmfs
         Standard observer colour matching functions, default to the
         *CIE 1931 2 Degree Standard Observer*.
@@ -439,6 +446,16 @@ def is_within_visible_spectrum(
     array([ True, False], dtype=bool)
     """
 
+    XYZ = np.asarray(XYZ)
+    if XYZ.shape[-1] == 2:
+        return _is_within_visible_xy(
+            XYZ,
+            cmfs=cmfs,
+            illuminant=illuminant,
+            tolerance=tolerance,
+            **kwargs,
+        )
+
     cmfs, illuminant = handle_spectral_arguments(
         cmfs,
         illuminant,
@@ -456,3 +473,76 @@ def is_within_visible_spectrum(
         )
 
     return is_within_mesh_volume(XYZ, vertices, tolerance)
+
+
+def _is_within_visible_xy(
+    xy: ArrayLike,
+    cmfs: MultiSpectralDistributions | None = None,
+    illuminant: SpectralDistribution | None = None,
+    tolerance: float = 100 * EPSILON,
+    **kwargs: Any,
+) -> NDArrayFloat:
+    """
+    Return whether given *CIE XYZ* tristimulus values are within the visible
+    spectrum volume, i.e. *Rösch-MacAdam* colour solid, for given colour
+    matching functions and illuminant.
+
+    Parameters
+    ----------
+    XYZ
+        *CIE XYZ* tristimulus values.
+    cmfs
+        Standard observer colour matching functions, default to the
+        *CIE 1931 2 Degree Standard Observer*.
+    illuminant
+        Illuminant spectral distribution, default to *CIE Illuminant E*.
+    tolerance
+        Tolerance allowed in the inside-triangle check.
+
+    Other Parameters
+    ----------------
+    kwargs
+        {:func:`colour.msds_to_XYZ`},
+        See the documentation of the previously listed definition.
+
+    Returns
+    -------
+    :class:`numpy.ndarray`
+        Are *CIE XYZ* tristimulus values within the visible spectrum volume,
+        i.e. *Rösch-MacAdam* colour solid.
+
+    Notes
+    -----
+    +------------+-----------------------+---------------+
+    | **Domain** | **Scale - Reference** | **Scale - 1** |
+    +============+=======================+===============+
+    | ``XYZ``    | [0, 1]                | [0, 1]        |
+    +------------+-----------------------+---------------+
+
+    Examples
+    --------
+    >>> import numpy as np
+    >>> is_within_visible_spectrum(np.array([0.33, 0.33]))
+    array(True, dtype=bool)
+    >>> a = np.array([[0.33, 0.33], [0.1, 0.1]])
+    >>> is_within_visible_spectrum(a)
+    array([ True, False], dtype=bool)
+    """
+
+    cmfs, illuminant = handle_spectral_arguments(
+        cmfs,
+        illuminant,
+        "CIE 1931 2 Degree Standard Observer",
+        "E",
+        SPECTRAL_SHAPE_OUTER_SURFACE_XYZ,
+    )
+
+    key = (hash(cmfs), hash(illuminant), str(kwargs))
+    vertices = _CACHE_OUTER_SURFACE_XYZ_POINTS.get(key)
+
+    if vertices is None:
+        _CACHE_OUTER_SURFACE_XYZ_POINTS[key] = vertices = XYZ_to_xy(
+            cmfs.values
+        )
+
+    return is_within_mesh_volume(xy, vertices, tolerance)

colour/volume/tests/test_spectrum.py

@@ -197,6 +197,16 @@ class TestIsWithinVisibleSpectrum(unittest.TestCase):
     definition unit tests methods.
     """
 
+    def test_is_within_visible_spectrum_xy(self):
+        """Test :func:`colour.volume.spectrum.is_within_visible_spectrum`
+        detection and use of xy chromaticity.
+        """
+
+        samples = [[0.1, 0.1], [0.3, 0.3]]
+        results = is_within_visible_spectrum(samples)
+
+        np.testing.assert_array_equal(results, (False, True))
+
     def test_is_within_visible_spectrum(self):
         """
         Test :func:`colour.volume.spectrum.is_within_visible_spectrum`