Implement support for "Munish Ragoo and Farup (2021)" "Optimised IPT"…

… Colourspace.

BIBLIOGRAPHY.bib

@@ -2550,6 +2550,19 @@ @article{Morovic2000
   keywords     = {Cross-media reproduction,Gamut boundary
     calculation,Gamut mapping},
 }
+@article{MunishRagoo2021,
+  title        = {Optimising a {{Euclidean Colour Space Transform}}
+    for {{Colour Order}} and {{Perceptual Uniformity}}},
+  author       = {Munish Ragoo, Luvin and Farup, Ivar},
+  year         = 2021,
+  month        = nov,
+  journal      = {Color and Imaging Conference},
+  volume       = 29,
+  number       = 1,
+  pages        = {282--287},
+  issn         = {2166-9635},
+  doi          = {10.2352/issn.2169-2629.2021.29.282},
+}
 @misc{MunsellColorScienceb,
   title        = {Macbeth {{Colorchecker}}},
   author       = {{Munsell Color Science}},

README.rst

@@ -741,6 +741,14 @@ IPT Colourspace
     >>> colour.XYZ_to_IPT([0.20654008, 0.12197225, 0.05136952])
     array([ 0.38426191,  0.38487306,  0.18886838])
 
+Munish Ragoo and Farup (2021) Optimised IPT Colourspace
+*******************************************************
+
+.. code-block:: python
+
+    >>> colour.XYZ_to_IPT([0.20654008, 0.12197225, 0.05136952])
+    array([ 0.42248243,  0.2910514 ,  0.20410663])
+
 DIN99 Colourspace and DIN99b, DIN99c, DIN99d Refined Formulas
 *************************************************************
 

colour/__init__.py

@@ -253,6 +253,7 @@
     IgPgTg_to_XYZ,
     IPT_hue_angle,
     IPT_to_XYZ,
+    IPT_Munish2021_to_XYZ,
     JMh_CAM16_to_CAM16LCD,
     JMh_CAM16_to_CAM16SCD,
     JMh_CAM16_to_CAM16UCS,
@@ -313,6 +314,7 @@
     XYZ_to_ICtCp,
     XYZ_to_IgPgTg,
     XYZ_to_IPT,
+    XYZ_to_IPT_Munish2021,
     XYZ_to_Jzazbz,
     XYZ_to_K_ab_HunterLab1966,
     XYZ_to_Lab,
@@ -665,6 +667,7 @@ def __getattr__(self, attribute) -> Any:
     "IgPgTg_to_XYZ",
     "IPT_hue_angle",
     "IPT_to_XYZ",
+    "IPT_Munish2021_to_XYZ",
     "JMh_CAM16_to_CAM16LCD",
     "JMh_CAM16_to_CAM16SCD",
     "JMh_CAM16_to_CAM16UCS",
@@ -725,6 +728,7 @@ def __getattr__(self, attribute) -> Any:
     "XYZ_to_ICtCp",
     "XYZ_to_IgPgTg",
     "XYZ_to_IPT",
+    "XYZ_to_IPT_Munish2021",
     "XYZ_to_Jzazbz",
     "XYZ_to_K_ab_HunterLab1966",
     "XYZ_to_Lab",

colour/examples/models/examples_models.py

@@ -307,7 +307,6 @@
 )
 print(colour.ICaCb_to_XYZ(ICaCb))
 
-XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
 message_box(
     f'Converting to "IgPgTg" colourspace from given "CIE XYZ" tristimulus '
     f"values:\n\n\t{XYZ}"
@@ -325,7 +324,6 @@
 
 print("\n")
 
-XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
 message_box(
     f'Converting to "IPT" colourspace from given "CIE XYZ" tristimulus '
     f"values:\n\n\t{XYZ}"
@@ -343,6 +341,24 @@
 
 print("\n")
 
+message_box(
+    f'Converting to "Munish Ragoo and Farup (2021)" "Optimised IPT" '
+    f'colourspace from given "CIE XYZ" tristimulus values:\n\n\t{XYZ}'
+)
+print(colour.XYZ_to_IPT_Munish2021(XYZ))
+
+print("\n")
+
+IPT = np.array([0.42248243, 4.05710276, 0.20410663])
+message_box(
+    f'Converting to "CIE XYZ" tristimulus values from given'
+    f'"Munish Ragoo and Farup (2021)" "Optimised IPT" colourspace '
+    f"values:\n\n\t{IPT}"
+)
+print(colour.IPT_Munish2021_to_XYZ(IPT))
+
+print("\n")
+
 message_box(
     f'Converting to "hdr-CIELab" colourspace from given "CIE XYZ" tristimulus '
     f"values:\n\n\t{XYZ}"

colour/graph/conversion.py

@@ -79,6 +79,7 @@
     IHLS_to_RGB,
     IgPgTg_to_XYZ,
     IPT_to_XYZ,
+    IPT_Munish2021_to_XYZ,
     JMh_CAM16_to_CAM16LCD,
     JMh_CAM16_to_CAM16SCD,
     JMh_CAM16_to_CAM16UCS,
@@ -122,6 +123,7 @@
     XYZ_to_ICtCp,
     XYZ_to_IgPgTg,
     XYZ_to_IPT,
+    XYZ_to_IPT_Munish2021,
     XYZ_to_Jzazbz,
     XYZ_to_Lab,
     XYZ_to_Luv,
@@ -663,6 +665,8 @@ def RGB_luminance_to_RGB(Y: FloatingOrArrayLike) -> NDArray:
     ("IgPgTg", "CIE XYZ", IgPgTg_to_XYZ),
     ("CIE XYZ", "IPT", XYZ_to_IPT),
     ("IPT", "CIE XYZ", IPT_to_XYZ),
+    ("CIE XYZ", "IPT Munish 2021", XYZ_to_IPT_Munish2021),
+    ("IPT Munish 2021", "CIE XYZ", IPT_Munish2021_to_XYZ),
     ("CIE XYZ", "Jzazbz", XYZ_to_Jzazbz),
     ("Jzazbz", "CIE XYZ", Jzazbz_to_XYZ),
     ("CIE XYZ", "hdr-IPT", XYZ_to_hdr_IPT),

colour/models/__init__.py

@@ -92,6 +92,7 @@
     Izazbz_to_XYZ,
     Jzazbz_to_XYZ,
 )
+from .munish2021 import XYZ_to_IPT_Munish2021, IPT_Munish2021_to_XYZ
 from .hdr_ipt import HDR_IPT_METHODS, XYZ_to_hdr_IPT, hdr_IPT_to_XYZ
 from .oklab import XYZ_to_Oklab, Oklab_to_XYZ
 from .osa_ucs import XYZ_to_OSA_UCS, OSA_UCS_to_XYZ
@@ -452,6 +453,10 @@
     "Izazbz_to_XYZ",
     "Jzazbz_to_XYZ",
 ]
+__all__ += [
+    "XYZ_to_IPT_Munish2021",
+    "IPT_Munish2021_to_XYZ",
+]
 __all__ += [
     "HDR_IPT_METHODS",
     "XYZ_to_hdr_IPT",

colour/models/common.py

@@ -75,6 +75,7 @@
     "ICaCb",
     "ICtCp",
     "IPT",
+    "IPT Munish 2021",
     "IgPgTg",
     "Jzazbz",
     "OSA UCS",
@@ -110,6 +111,7 @@
             "ICaCb": ("$I$", "$C_a$", "$C_b$"),
             "ICtCp": ("$I$", "$C_T$", "$C_P$"),
             "IPT": ("I", "P", "T"),
+            "IPT Munish 2021": ("I", "P", "T"),
             "IgPgTg": ("$I_G$", "$P_G$", "$T_G$"),
             "Jzazbz": ("$J_z$", "$a_z$", "$b_z$"),
             "OSA UCS": ("L", "j", "g"),
@@ -145,6 +147,7 @@
         "ICaCb": np.array([1, 1, 1]),
         "ICtCp": np.array([1, 1, 1]),
         "IPT": np.array([1, 1, 1]),
+        "IPT Munish 2021": np.array([1, 1, 1]),
         "IgPgTg": np.array([1, 1, 1]),
         "Jzazbz": np.array([1, 1, 1]),
         "OSA UCS": np.array([100, 100, 100]),

colour/models/munish2021.py

@@ -0,0 +1,179 @@
+"""
+Munish Ragoo and Farup (2021) Optimised IPT Colourspace
+=======================================================
+
+Defines the *Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace
+transformations:
+
+-   :func:`colour.XYZ_to_IPT_Munish2021`
+-   :func:`colour.IPT_Munish2021_to_XYZ`
+
+References
+----------
+-   :cite:`Munish2021` : Munish Ragoo, L., & Farup, I. (2021). Optimising
+    a Euclidean Colour Space Transform for Colour Order and Perceptual
+    Uniformity. Color and Imaging Conference, 29(1), 282-287.
+    doi:10.2352/issn.2169-2629.2021.29.282
+"""
+
+from __future__ import annotations
+
+import numpy as np
+from functools import partial
+
+from colour.algebra import spow
+from colour.models import Iab_to_XYZ, XYZ_to_Iab
+from colour.hints import ArrayLike, NDArray
+
+__author__ = "Colour Developers"
+__copyright__ = "Copyright 2013 Colour Developers"
+__license__ = "New BSD License - https://opensource.org/licenses/BSD-3-Clause"
+__maintainer__ = "Colour Developers"
+__email__ = "colour-developers@colour-science.org"
+__status__ = "Production"
+
+__all__ = [
+    "MATRIX_IPT_XYZ_TO_LMS",
+    "MATRIX_IPT_LMS_TO_XYZ",
+    "MATRIX_IPT_LMS_P_TO_IPT",
+    "MATRIX_IPT_IPT_TO_LMS_P",
+    "XYZ_to_IPT_Munish2021",
+    "IPT_Munish2021_to_XYZ",
+]
+
+MATRIX_IPT_XYZ_TO_LMS: NDArray = np.array(
+    [
+        [0.4321, 0.6906, -0.0930],
+        [-0.1793, 1.1458, 0.0226],
+        [0.0631, 0.1532, 0.7226],
+    ]
+)
+"""*CIE XYZ* tristimulus values to normalised cone responses matrix."""
+
+MATRIX_IPT_LMS_TO_XYZ: NDArray = np.linalg.inv(MATRIX_IPT_XYZ_TO_LMS)
+"""Normalised cone responses to *CIE XYZ* tristimulus values matrix."""
+
+MATRIX_IPT_LMS_P_TO_IPT: NDArray = np.array(
+    [
+        [0.3037, 0.6688, 0.0276],
+        [3.9247, -4.7339, 0.8093],
+        [1.5932, -0.5205, -1.0727],
+    ]
+)
+"""
+Normalised non-linear cone responses to *Munish Ragoo and Farup (2021)*
+*Optimised IPT* colourspace matrix.
+"""
+
+MATRIX_IPT_IPT_TO_LMS_P: NDArray = np.linalg.inv(MATRIX_IPT_LMS_P_TO_IPT)
+"""
+*Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace to normalised
+non-linear cone responses matrix.
+"""
+
+
+def XYZ_to_IPT_Munish2021(XYZ: ArrayLike) -> NDArray:
+    """
+    Convert from *CIE XYZ* tristimulus values to
+    *Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace.
+
+    Parameters
+    ----------
+    XYZ
+        *CIE XYZ* tristimulus values.
+
+    Returns
+    -------
+    :class:`numpy.ndarray`
+        *Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace array.
+
+    Notes
+    -----
+    +------------+-----------------------+-----------------+
+    | **Domain** | **Scale - Reference** | **Scale - 1**   |
+    +============+=======================+=================+
+    | ``XYZ``    | [0, 1]                | [0, 1]          |
+    +------------+-----------------------+-----------------+
+
+    +------------+-----------------------+-----------------+
+    | **Range**  | **Scale - Reference** | **Scale - 1**   |
+    +============+=======================+=================+
+    | ``IPT``    | ``I`` : [0, 1]        | ``I`` : [0, 1]  |
+    |            |                       |                 |
+    |            | ``P`` : [-1, 1]       | ``P`` : [-1, 1] |
+    |            |                       |                 |
+    |            | ``T`` : [-1, 1]       | ``T`` : [-1, 1] |
+    +------------+-----------------------+-----------------+
+
+    -   Input *CIE XYZ* tristimulus values must be adapted to
+        *CIE Standard Illuminant D Series* *D65*.
+
+    References
+    ----------
+    :cite:`Munish2021`
+
+    Examples
+    --------
+    >>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
+    >>> XYZ_to_IPT_Munish2021(XYZ)  # doctest: +ELLIPSIS
+    array([ 0.4224824...,  0.2910514...,  0.2041066...])
+    """
+
+    return XYZ_to_Iab(
+        XYZ,
+        partial(spow, p=0.4071),
+        MATRIX_IPT_XYZ_TO_LMS,
+        MATRIX_IPT_LMS_P_TO_IPT,
+    )
+
+
+def IPT_Munish2021_to_XYZ(IPT: ArrayLike) -> NDArray:
+    """
+    Convert from *Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace to
+    *CIE XYZ* tristimulus values.
+
+    Parameters
+    ----------
+    IPT
+        *Munish Ragoo and Farup (2021)* *Optimised IPT* colourspace array.
+
+    Returns
+    -------
+    :class:`numpy.ndarray`
+        *CIE XYZ* tristimulus values.
+
+    Notes
+    -----
+    +------------+-----------------------+-----------------+
+    | **Domain** | **Scale - Reference** | **Scale - 1**   |
+    +============+=======================+=================+
+    | ``IPT``    | ``I`` : [0, 1]        | ``I`` : [0, 1]  |
+    |            |                       |                 |
+    |            | ``P`` : [-1, 1]       | ``P`` : [-1, 1] |
+    |            |                       |                 |
+    |            | ``T`` : [-1, 1]       | ``T`` : [-1, 1] |
+    +------------+-----------------------+-----------------+
+
+    +------------+-----------------------+-----------------+
+    | **Range**  | **Scale - Reference** | **Scale - 1**   |
+    +============+=======================+=================+
+    | ``XYZ``    | [0, 1]                | [0, 1]          |
+    +------------+-----------------------+-----------------+
+
+    References
+    ----------
+    :cite:`Munish2021`
+
+    Examples
+    --------
+    >>> IPT = np.array([0.42248243, 0.2910514, 0.20410663])
+    >>> IPT_Munish2021_to_XYZ(IPT)  # doctest: +ELLIPSIS
+    array([ 0.2065400...,  0.1219722...,  0.0513695...])
+    """
+
+    return Iab_to_XYZ(
+        IPT,
+        partial(spow, p=1 / 0.4071),
+        MATRIX_IPT_IPT_TO_LMS_P,
+        MATRIX_IPT_LMS_TO_XYZ,
+    )