Colour 0.4.7 - Alpha Milestone

Features

Dependencies

• Support for Python 3.14 was implemented. (#1379, @ KelSolaar)
• scipy has been made optional.
• imageio has been made optional.
• typing-extensions requirement has been dropped.

The following scientific packages minimum versions are required:

• numpy >= 2.0.0
• scipy >= 1.13.0
• matplotlib >= 3.9
• networkx >= 3.3
• pandas >= 2.2

Documentation

• Each documented object has been verified and processed with a LLM to improve consistency and correct typos and mistakes. (#1352, #1357, @KelSolaar, Claude Code)

colour.adaptation

• Implement support for Li (2025) chromatic adaptation transform with colour.chromatic_adaptation_Li2025 definition. (#1349, #1356, @UltraMo114, @KelSolaar, Claude Code)

colour.appearance

• Implement support for sCAM colour appearance model with colour.XYZ_to_sCAM and colour.sCAM_to_XYZ definitions. (#1349, #1356, @UltraMo114, @KelSolaar, Claude Code)

colour.io

• The colour.LUT3D.invert method has been improved and yields smoother results via Shepard interpolation and iterative adaptive smoothing. (54637c4, @KelSolaar, Claude Code)

colour.difference

• Implement support for Metamerism Index computation with colour.difference.Lab_to_metamerism_index and colour.difference.XYZ_to_metamerism_index definitions. (#1374, @lassefschmidt)

colour.models

• Implement support for sUCS colour space model with colour.XYZ_to_sUCS, colour.sUCS_to_XYZ, colour.models.sUCS_Iab_to_sUCS_ICh and colour.models.sUCS_ICh_to_sUCS_Iab definitions. (#1349, #1356, @UltraMo114, @KelSolaar, Claude Code)

• Implement Color Interop Forum recommendation for ColorSpace Encodings for Texture Assets and CG Rendering. (#1316, @KelSolaar)

The following RGB colourspaces were added:

• colour.models.RGB_COLOURSPACE_LIN_REC709_SCENE
• colour.models.RGB_COLOURSPACE_LIN_P3D65_SCENE
• colour.models.RGB_COLOURSPACE_LIN_REC2020_SCENE
• colour.models.RGB_COLOURSPACE_LIN_ADOBERGB_SCENE
• colour.models.RGB_COLOURSPACE_LIN_CIEXYZD65_SCENE
• colour.models.RGB_COLOURSPACE_SRGB_REC709_SCENE
• colour.models.RGB_COLOURSPACE_G22_REC709_SCENE
• colour.models.RGB_COLOURSPACE_G18_REC709_SCENE
• colour.models.RGB_COLOURSPACE_SRGB_AP1_SCENE
• colour.models.RGB_COLOURSPACE_G22_AP1_SCENE
• colour.models.RGB_COLOURSPACE_SRGB_P3D65_SCENE
• colour.models.RGB_COLOURSPACE_G22_ADOBERGB_SCENE

The following aliases were added:

• lin_ap1_scene

• lin_ap0_scene

• lin_rec709_scene

• lin_p3d65_scene

• lin_rec2020_scene

• lin_adobergb_scene

• lin_ciexyzd65_scene

• srgb_rec709_scene

• g22_rec709_scene

• g18_rec709_scene

• srgb_ap1_scene

• g22_ap1_scene

• srgb_p3d65_scene

• g22_adobergb_scene

• Implement support for Filmlight E-Gamut 2 RGB colourspace with colour.models.RGB_COLOURSPACE_FILMLIGHT_E_GAMUT_2 attribute. (#1323, @nick-shaw)

• Implement support for Fujifilm F-Gamut C RGB colourspace with colour.models.RGB_COLOURSPACE_F_GAMUT_C attribute. (#1317, @KelSolaar)

• Implement support for Xiaomi Mi-Log Profile with colour.models.log_encoding_MiLog and colour.models.log_decoding_MiLog definitions. (#1359, @KelSolaar, Claude Code)

• Implement Schlömer (2019) improved OSA-UCS to CIE XYZ conversion: This reduced failure cases significantly and brought x28.5 increased performance. (#1372, @KelSolaar, Claude Code)

colour.phenomena

• Implement support for the Transfer Matrix Method: The main definition is colour.phenomena.matrix_transfer_tmm that computes transfer matrices for multilayer thin film structures with full vectorisation across wavelength, angle and thickness. (#1366, @KelSolaar, Claude Code)

The colour.phenomena.thin_film_tmm and colour.phenomena.multilayer_tmm definitions compute thin film and multilayer reflectance / transmittance respectively.

• colour.phenomena.snell_law
• colour.phenomena.polarised_light_magnitude_elements
• colour.phenomena.polarised_light_reflection_amplitude
• colour.phenomena.polarised_light_reflection_coefficient
• colour.phenomena.polarised_light_transmission_amplitude
• colour.phenomena.polarised_light_transmission_coefficient
• colour.phenomena.TransferMatrixResult
• colour.phenomena.matrix_transfer_tmm
• colour.phenomena.light_water_molar_refraction_Schiebener1990
• colour.phenomena.light_water_refractive_index_Schiebener1990
• colour.phenomena.thin_film_tmm
• colour.phenomena.multilayer_tmm

New plotting definitions were added, most notable ones being colour.plotting.plot_thin_film_iridescence, colour.plotting.plot_thin_film_reflectance_map and colour.plotting.plot_multi_layer_stack.

• colour.plotting.plot_single_layer_thin_film
• colour.plotting.plot_multi_layer_thin_film
• colour.plotting.plot_thin_film_comparison
• colour.plotting.plot_thin_film_spectrum
• colour.plotting.plot_thin_film_iridescence
• colour.plotting.plot_thin_film_reflectance_map
• colour.plotting.plot_multi_layer_stack

colour.quality

• Implement support for Spectral radiance factors of test-colour sample #15 of the Japanese skin complexion, 5nm wavelength steps. (#1337, @cmuellner, @KelSolaar)
• The colour.spectral_similarity_index definition now also supports colour.MultiSpectralDistributions as parameters. (#1373, #1370, @KelSolaar)

colour.utilities

Introduce a metadata system for documenting expected input/output value ranges in function signatures using Annotated type hints. Functions now declare scale information (e.g., [0, 1], [0, 100], [0, 360]) directly in their type annotations. (#1371, @KelSolaar)

Type Aliases for Common Scales

def XYZ_to_Lab(XYZ: Domain1) -> Range100:  # Domain [0, 1], Range [0, 100]
    ...

def Lab_to_LCHab(Lab: Domain100_100_360) -> Range100_100_360:  # Tuple scales
    ...

Metadata Extraction

from colour.utilities import get_domain_range_scale_metadata

metadata = get_domain_range_scale_metadata(XYZ_to_Lab)
# {'domain': {'XYZ': 1}, 'range': 100}

Automatic Scaling in Automatic Colour Conversion Graph

Lab = convert(XYZ, "CIE XYZ", "CIE Lab", to_reference_scale=True)  # Returns Lab in [0, 100]
XYZ = convert(Lab_native, "CIE Lab", "CIE XYZ", from_reference_scale=True)  # Accepts Lab in [0, 100]

Performance

Import Time

• scipy has been made optional to reduce import times. (#1375, #1376, @KelSolaar)

colour.algebra

• Optimise colour.algebra.table_interpolation_trilinear and colour.algebra.table_interpolation_tetrahedral definitions for 1.3x performance improvement. (b8e1583, @KelSolaar, Claude Code)

colour.temperature

• Vectorise colour.temperature.uv_to_CCT_Robertson1968 and colour.temperature.CCT_to_uv_Robertson1968 definitions for 30x and 90x performance improvement. (#1367, @KelSolaar, Claude Code)

Fixes

colour.utilities

• Ensure that colour.utilities.tsplit definition returns a contiguous copy of the input array. (9ba813d, @KelSolaar)

Changes

colour.algebra

• The colour.algebra.sdiv_mode context manager and colour.algebra.sdiv definition and other related objects now support two new modes:
  • Replace With Epsilon: Zero-division is avoided by replacing zero denominators with the machine epsilon value from :attr:colour.constants.EPSILON.
  • Warning Replace With Epsilon: Zero-division is avoided by replacing zero denominators with the machine epsilon value from :attr:colour.constants.EPSILON with a warning.

colour.colorimetry

• The colour.SpectralDistribution.interpolate definition has been updated to handle fractional wavelengths better. (#1328, @KelSolaar)
  • Numerical differences are expected if any of the following definitions were used with fractional wavelengths:
    • colour.SpectralDistribution.interpolate
    • colour.SpectralDistribution.align
    • colour.MultiSpectralDistributions.interpolate
    • colour.MultiSpectralDistributions.align
    • colour.colorimetry.reshape_sd
    • colour.colorimetry.reshape_msds

colour.models

Colour 0.4.6 - Alpha Milestone

Fixes

Dependencies

• trimesh was incorrectly added as a required dependency during the uv migration. (4649c11, @KelSolaar)

colour.models

• Revert c25934e which incorrectly changed Canon Cinema Gamut whitepoint to D55. (92dcd6d, @KelSolaar)

Colour 0.4.5 - Alpha Milestone

Features

Dependencies

• Support for Python 3.13 was implemented. (#1302, @ KelSolaar)
• Support for Numpy 2 was implemented. (#1279, @KelSolaar)
• pygraphviz was replaced with pydot so that installation is easier: pygraphviz needs to be built , which is not trivial, whereas pydot is a pure Python package.

The following scientific packages minimum versions are required:

• numpy >= 1.24
• scipy >= 1.10
• matplotlib >= 3.7
• networkx >= 3
• pandas >= 2

Development Environment

Astral's uv

• We switched from Poetry to uv and hatch for managing the development environment and build our wheels. (#1300)

  • uv is faster at resolving the environment and the team at astral.sh has been doing wonders for the Python ecosystem, we have been using ruff for a while now.
  • It is so good that it literally only requires uv run --with colour-science my_script.py to run a script using Colour.
  • Thanks a ton to @charliermarsh et al.!

• Improve static typing checks using multi-threading thanks to @erictraut suggestion.

Environment

It is now possible to create a ~/.colour-science/colour-science.jenv JSON file from which Colour will load environment variables from: (#1239, @KelSolaar)

{
  "COLOUR_SCIENCE__COLOUR__SHOW_WARNINGS_WITH_TRACEBACK": 1
}

The following new environment variables are now supported:

• COLOUR_SCIENCE__FILTER_RUNTIME_WARNINGS: Filter Colour runtime warnings.
• COLOUR_SCIENCE__FILTER_USAGE_WARNINGS: Filter Colour usage warnings.
• COLOUR_SCIENCE__FILTER_COLOUR_WARNINGS: Filter Colour warnings, this also filters Colour usage and runtime warnings.
• COLOUR_SCIENCE__FILTER_PYTHON_WARNINGS: Filter Python warnings.

Input and Output

• Definitions reading from and writing to files now support the pathlib.Path type. (ff4fe99, @KelSolaar)

colour.adaptation

• Implement support for vK20 chromatic adaptation transform with colour.adaptation.matrix_chromatic_adaptation_vk20 and colour.adaptation.chromatic_adaptation_vK20 definitions. (#1131, @KelSolaar)

colour.characterisation

• Add the ColorChecker SG chromaticity coordinates with the colour.CCS_COLOURCHECKERS["ColorCheckerSG - Before November 2014"] and colour.CCS_COLOURCHECKERS["ColorCheckerSG - After November 2014"] attribute keys.

colour.colorimetry

• Use shape if passed, to also reshape the colour.continuous.AbstractContinuousSignal sub-classes in colour.colorimetry.sd_to_XYZ_integration definition. (#1250, @KelSolaar)

colour.models

• Programmatically add polar conversions to the following definitions: (#1183, #1272, @KelSolaar)

• colour.Lab_to_LCHab *

• colour.LCHab_to_Lab *

• colour.Luv_to_LCHuv *

• colour.LCHuv_to_Luv *

• colour.hdr_CIELab_to_hdr_CIELCHab

• colour.hdr_CIELCHab_to_hdr_CIELab

• colour.Hunter_Lab_to_Hunter_LCHab

• colour.Hunter_LCHab_to_Hunter_Lab

• colour.Hunter_Rdab_to_Hunter_RdCHab

• colour.Hunter_RdCHab_to_Hunter_Rdab

• colour.ICaCb_to_ICHab

• colour.ICHab_to_ICaCb

• colour.ICtCp_to_ICHtp

• colour.ICHtp_to_ICtCp

• colour.IgPgTg_to_IgCHpt

• colour.IgCHpt_to_IgPgTg

• colour.IPT_to_ICH

• colour.ICH_to_IPT

• colour.Izazbz_to_IzCHab

• colour.IzCHab_to_Izazbz

• colour.Jzazbz_to_JzCHab

• colour.JzCHab_to_Jzazbz

• colour.hdr_IPT_to_hdr_ICH

• colour.hdr_ICH_to_hdr_IPT

• colour.Oklab_to_Oklch

• colour.Oklch_to_Oklab

• colour.ProLab_to_ProLCHab

• colour.ProLCHab_to_ProLab

• colour.IPT_Ragoo2021_to_ICH_Ragoo2021

• colour.ICH_Ragoo2021_to_IPT_Ragoo2021

* Now programmatically defined

colour.utilities

Port-Based Nodes and Graphs (#1277, @KelSolaar)

6 new classes were introduced to support for a port-based node-graph:

• colour.utilities.Port
• colour.utilities.PortNode
• colour.utilities.PortGraph
• colour.utilities.For
• colour.utilities.ParallelForThread
• colour.utilities.ParallelForMultiProcess

They enable the construction of processing graphs:

class NodeAdd(PortNode):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.description = "Perform the addition of the two input port values."

        self.add_input_port("a")
        self.add_input_port("b")
        self.add_output_port("output")

    def process(self):
        a = self.get_input("a")
        b = self.get_input("b")

        if a is None or b is None:
            return

        self._output_ports["output"].value = a + b

        self.dirty = False

class NodeMultiply(PortNode):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)

        self.description = (
            "Perform the multiplication of the two input port values."
        )

        self.add_input_port("a")
        self.add_input_port("b")
        self.add_output_port("output")

    def process(self):
        a = self.get_input("a")
        b = self.get_input("b")

        if a is None or b is None:
            return

        self._output_ports["output"].value = a * b

        self.dirty = False

node_add = NodeAdd()
node_add.set_input("a", 1)
node_add.set_input("b", 1)
node_multiply = NodeMultiply()
node_multiply.set_input("b", 2)

graph = PortGraph()

graph.add_node(node_add)
graph.add_node(node_multiply)

graph.connect(node_add, "output", node_multiply, "a")

graph.process()

print(node_multiply.get_output("output"))
graph.to_graphviz().draw("Graph.png", prog="dot")

colour-hdri uses the new classes to implement a multi-processed HDRI merging graph: https://github.com/colour-science/colour-hdri/blob/develop/colour_hdri/examples/examples_advanced_processing_with_an_input_device_transform.ipynb

Fixes

colour.colorimetry

• Fix issue where colour.colorimetry.sds_and_msds_to_msds definition did not always copy the converted spectral distributions and was causing seemingly random unit tests failure. (891d364, @KelSolaar)
• Fix issue when passing a colour.MultiSpectralDistributions to colour.sd_to_XYZ definition using the ASTM E308 method. (20fb963, @KelSolaar, @gul916)

colour.io

• Ensure that colour.io.process_image_OpenColorIO definition handles non-contiguous arrays. (387c9e5, @nick-shaw, @KelSolaar)

colour.models

• Change Canon Cinema Gamut whitepoint to D55. (c25934e, @MrLixm, @KelSolaar)

colour.notation

• Reduce various thresholds in Munsell Renotation computations to allow sRGB colours to be converted. (#1173, 4b0c38d, @KelSolaar)

colour.utilities

• Ensure that caches are systematically cleared when changing dtype: It was causing seemingly random unit tests failure. (8faeb09, @KelSolaar)

Changes

colour.algebra

colour.plotting

colour.utilities

• ~colour.utilities.is_string: (@KelSolaar)
  • Remove

Colour 0.4.4 - Alpha Milestone

This release implements support for Python 3.12 (#1224).

We are now using isort to order our imports. We improved the repository style using the Scientific Python Repository Review page.

colour-visuals was made public: It is a new repository implementing various WebGPU-based visuals on top of Colour and pygfx.

Features

Packaging

We have solved the clash with https://github.com/vaab/colour by loading a known subset of the objects given by vaab/colour-0.1.5 into our namespace if the COLOUR_SCIENCE__COLOUR__IMPORT_VAAB_COLOUR=True environment variable is defined. (#1222, @KelSolaar, @tjdcs, @MichaelMauderer)

See the following issues for more information:

• #958
• #1221
• vaab/colour#62

colour.hints

• Various new literals have been added to help packages using Colourwith typing annotations. (#1198, @KelSolaar, @jamesmyatt)

colour.models

• Implement support for Apple Log Profile with colour.models.log_encoding_AppleLogProfile and colour.models.log_decoding_AppleLogProfile definitions. (@KelSolaar)

colour.plotting

• Add new definitions to generate data useful for other plotting definitions and used by colour-visuals: (@KelSolaar)

• colour.plotting.lines_daylight_locus

• colour.plotting.lines_planckian_locus

• colour.plotting.lines_pointer_gamut

• colour.plotting.lines_spectral_locus

Fixes

colour.continuous

• Ensure that colour.continuous.AbstractContinuousFunction class and sub-classes, e.g. colour.SpectralDistribution class, can be pickled. (#66c26b6, @KelSolaar)

colour.difference

• Fix numerical precision issue in colour.difference.delta_E_CIE1994 definition. (#1206, @volrak, @KelSolaar)

colour.utilities

• Fix issue in colour.utilities.verbose.multiline_repr definition when an attribute representation is None. (#1466, @KelSolaar)

Changes

Unit Tests

• We have changed our unit tests to use np.testing.assert_allclose rather than np.testing.assert_array_almost_equal to help with tests failing on Github Actions because of minor precision issues when using pytest-xdist, multi-threading and caching. (@KelSolaar)

colour.constants

Colour 0.4.3 - Alpha Milestone

We worked on many optimisations around colour quality metrics that should result in overall performance increase, thanks again to @tjdcs for the heavy lifting!

@charliermarsh's ruff is now used as a replacement for:

• flake8
• pydocstyle
• pyupgrade

We also replaced mypy with pyright for performance reasons. We took that opportunity to simplify our type annotations.

The colour.XYZ_to_RGB and colour.RGB_to_XYZ definition signatures have been changed to be easier to use, please update any code using them. See #1127 for more information.

With this release, the following scientific packages minimum versions are required:

• numpy >= 1.22
• scipy >= 1.8
• matplotlib >= 3.5
• networkx >= 2.7
• pandas >= 1.4

Features

colour.characterisation

• Add TE226 V2 colour checker reference values. (#1113, #901, @Rusching)
• Add colour.apply_matrix_colour_correction definition and colour.APPLY_MATRIX_COLOUR_CORRECTION_METHODS attribute to conveniently apply a colour-correction matrix computed with the colour.matrix_colour_correction definition. (@KelSolaar)
• Add terms 4 and 35 to Cheung (2004) polynomial transformation. (#1160, @chnmasta05)

colour.colorimetry

• The continuous signal classes are now iterable, e.g. colour.SpectralDistribution and colour.MultiSpectralDistributions. (#1088, @KelSolaar)

import colour

sd = colour.SDS_ILLUMINANTS["A"]
for i in sd:
    print(i)

[ 300.          0.930483]
[ 305.         1.12821]
[ 310.         1.35769]
...
[ 780.     241.675]

import colour

sd = colour.MSDS_CMFS["CIE 2012 2 Degree Standard Observer"]
for i in sd:
    print(i)

[  3.90000000e+02   3.76964700e-03   4.14616100e-04   1.84726000e-02]
[  3.91000000e+02   4.53241600e-03   5.02833300e-04   2.22110100e-02]
[  3.92000000e+02   5.44655300e-03   6.08499100e-04   2.66981900e-02]
...
[  8.30000000e+02   1.76246500e-06   7.05386000e-07   0.00000000e+00]

colour.models

• Implement support for Kirk (2019) Yrg colourspace with colour.XYZ_to_Yrg and colour.Yrg_to_XYZ definitions. (#1152, @KelSolaar)
• Implement support for Fujifilm F-Log2 encodings with colour.models.log_decoding_FLog2 and colour.models.log_encoding_FLog2 definitions. (#1076, @zachlewis)
• Implement support for PLASA ANSI E1.54 colourspace with colour.models.RGB_COLOURSPACE_PLASA_ANSI_E154 attribute. (#1193, @KelSolaar)

colour.notation

• Implement support for CSS Color 3 with colour.notation.CSS_COLOR_3 attribute and colour.notation.keyword_to_RGB_CSSColor3 definition. (#1140, @KelSolaar)

colour.plotting

• Make RGB encoding optional in colour.plotting.plot_RGB_chromaticities_in_chromaticity_diagram_CIE1931, colour.plotting.plot_RGB_chromaticities_in_chromaticity_diagram_CIE1960UCS and colour.plotting.plot_RGB_chromaticities_in_chromaticity_diagram_CIE1976UCS definitions. (@KelSolaar)

RGB = np.random.random((128, 128, 3))
plot_RGB_chromaticities_in_chromaticity_diagram(RGB, "ITU-R BT.709", scatter_kwargs={"apply_cctf_encoding": False})

• Add a new colour.plotting.temperature.plot_daylight_locus definition. (@KelSolaar)
• Add a new planckian_locus_use_mireds keyword argument to colour.plotting.temperature.plot_planckian_locus definition. (@KelSolaar)

colour.temperature

• Add colour.temperature.mired_to_CCT and colour.temperature.CCT_to_mired definitions to perform micro reciprocal degree and CCT conversions. (#1114, @KelSolaar)
• Add colour.temperature.XYZ_to_CCT_Ohno2013 and colour.temperature.CCT_to_XYZ_Ohno2013 convenient definitions. (#1120, @tjdcs)

colour.utilities

• Add colour.utilities.int_digest definition using xxhash to compute 64-bit integer hashes. (#1149, @KelSolaar, @tjdcs)

Performance

• The Colour Fidelity Index (2017), i.e. colour.quality.colour_fidelity_index_CIE2017 definition, and TM 30-18, i.e. colour.quality.colour_fidelity_index_ANSIIESTM3018 definition, metrics performance has been improved by x100 thanks to overall optimizations, e.g. colour.temperature.uv_to_CCT_Ohno2013 definition is x5 faster. (#1120, @tjdcs, @KelSolaar)

Fixes

Dependencies

• Implement support for Numpy 1.24.0. (#1087, @KelSolaar)

colour.io

• Fix incorrect bit-depth conversion in colour.io.write_image_OpenImageIO definition when writing 16-bit integer images (82ef2c4, @nick-shaw, @KelSolaar)

colour.colorimetry

• Fix incorrect colour.colorimetry.sd_gaussian_fwhm definition output (#1184, @EricFlyMeToTheMoon, @tjdcs, @KelSolaar)

colour.models

• Implement various minor corrections from Sarifuddin (2021) to colour.RGB_to_HCL definition. (1a580ef, @KelSolaar)

colour.phenomena

• Fix incorrect CO2 concentration scaling in colour.phenomena.rayleigh.F_air_Bodhaine1999 definition. (#307, #1167, @chnmasta05, @KelSolaar)

colour.utilities

• Fix dimensionality reduction issue in colour.utilities.as_float definition that was causing issue with 1-pixel images processing. (#1189, @KelSolaar, @MrLixm)

Changes

colour.colorimetry

colour.characterisation

• Ensure that the matrix returned by colour.matrix_idt definition is whitepoint preserving using the colour.characterisation.optimisation_factory_rawtoaces_v1 optimisation factory. (@KelSolaar)
• Implement support for Finlayson et al. (2015) root-polynomials colour correction with colour.characterisation.optimisation_factory_Oklab_15 optimisation factory. (@KelSolaar)
• The colour.matrix_idt definition optimisation factories are now returning 4 objects. (@KelSolaar)

colour.models

• The colour.XYZ_to_xy and colour.XYZ_to_xyY definitions do no return the parameter illuminant chromaticities when the luminance Y is equal to zero. This behaviour was motivated by a note from Bruce Justin Lindbloom but does not have a CIE or ASTM recommendation. (#1153, @KelSolaar)

Colour 0.4.2 - Alpha Milestone

This release implements support for Python 3.11. It includes the remaining contributions of the GSoC 2021 work from Cédric (@villirion). New RGB colourspaces, transfer functions, colour models and colour appearance models have been added. Various performance improvements have been implemented.

We would like to especially thanks @tjdcs for his recent contributions.

With this release, the minimum Python version is 3.9 and the following scientific packages minimum versions are required:

• numpy >= 1.20
• scipy >= 1.7
• matplotlib >= 3.4
• networkx >= 2.6
• pandas >= 1.3

Features

colour.appearance

• Implement support for Hellwig and Fairchild (2022) colour appearance model with colour.XYZ_to_Hellwig2022 and colour.Hellwig2022_to_XYZ definitions. (#972 @KelSolaar)
• Implement support for CIECAM16 colour appearance model with colour.XYZ_to_CIECAM16 and colour.CIECAM16_to_XYZ definitions. (#1015, @KelSolaar)

colour.colorimetry

• Add convenient colour.SpectralShape.wavelengths property. (@KelSolaar)

colour.difference

• Implement support for Recommendation ITU-R BT.2124 with colour.difference.delta_E_ITP definition. (#981, @sabarish-srinivasan)

colour.io

• Implement simple wrapper for the Color Transformation Language (CTL) with the colour.io.ctl_render and colour.io.process_image_ctl definitions. (#977, @KelSolaar)

colour.models

• Implement support for Munish Ragoo and Farup (2021) Optimised IPT colourspace with colour.XYZ_to_IPT_Munish2021 and colour.IPT_Munish2021_to_XYZ definitions. (#990, @KelSolaar)

• Implement support for Leica L-Log log encodings with colour.models.log_encoding_LLog and colour.models.log_decoding_LLog definitions. (#986, @KelSolaar, @nick-shaw, @zachlewis)

• Implement support for Recommendation ITU-T H.273 / INTERNATIONAL STANDARD ISO/IEC 23091-2 code points for video signal type identification with colour.COLOUR_PRIMARIES_ITUTH273, colour.TRANSFER_CHARACTERISTICS_ITUTH273 and colour.MATRIX_COEFFICIENTS_ITUTH273 attributes and colour.models.describe_video_signal_colour_primaries, colour.models.describe_video_signal_transfer_characteristics and colour.models.describe_video_signal_matrix_coefficients definitions. (#987, #1033, @fxthomas, @KelSolaar).

• Implement support for ARRI Wide Gamut 4 colourspace and ARRI LogC4 log encodings with colour.models.RGB_COLOURSPACE_ARRI_WIDE_GAMUT_4 attribute and colour.models.log_encoding_ARRILogC4 and colour.models.log_decoding_ARRILogC4 definitions. (#1056, @KelSolaar)

  For consistency:

  • The colour.models.RGB_COLOURSPACE_ALEXA_WIDE_GAMUT attribute has been renamed to RGB_COLOURSPACE_ARRI_WIDE_GAMUT_3.
  • The colour.models.log_encoding_ALEXALogC and colour.models.log_decoding_ALEXALogC definitions have been renamed to log_encoding_ARRILogC3 and log_decoding_ARRILogC3 respectively.
  • Keys in the various mappings, e.g. colour.RGB_COLOURSPACES, colour.LOG_ENCODINGS, have been renamed accordingly.

colour.recovery

GSoC - 2021

• Implement support for Jiang et al. (2013) camera RGB sensitivities recovery with colour.recovery.RGB_to_msds_camera_sensitivities_Jiang2013 definition. (#1002, @villirion, @KelSolaar)

colour.utilities

• The colour.utilities.CanonicalMapping and colour.utilities.LazyCanonicalMapping, fomerly colour.utilities.CaseInsensitiveMapping and colour.utilities.LazyCaseInsensitiveMapping, respectively, support canonical (and sluggified) keys: (#993, @KelSolaar, @zachlewis)

>>> import colour
>>> colour.RGB_COLOURSPACES['ALEXA Wide Gamut'].name
'ALEXA Wide Gamut'
>>> colour.RGB_COLOURSPACES['alexa-wide-gamut'].name
'ALEXA Wide Gamut'
>>> colour.RGB_COLOURSPACES['alexawidegamut'].name
'ALEXA Wide Gamut'
>>> 'ALEXA Wide Gamut' in colour.RGB_COLOURSPACES
True
>>> 'alexa-wide-gamut' in colour.RGB_COLOURSPACES
True
>>> 'alexawidegamut' in colour.RGB_COLOURSPACES
True
>>> del colour.RGB_COLOURSPACES['alexa-wide-gamut']
>>> 'ALEXA Wide Gamut' in colour.RGB_COLOURSPACES
False
>>> list(colour.RGB_COLOURSPACES.slugified_keys())
['aces2065-1', 'acescc', 'acescct', 'acescg', 'acesproxy', 'adobe-rgb-1998', 'adobe-wide-gamut-rgb', 'apple-rgb', 'best-rgb', 'beta-rgb', 'blackmagic-wide-gamut', 'cie-rgb', 'cinema-gamut', 'colormatch-rgb', 'dcdm-xyz', 'dci-p3', 'dci-p3-p', 'dji-d-gamut', 'dragoncolor', 'dragoncolor2', 'davinci-wide-gamut', 'display-p3', 'don-rgb-4', 'eci-rgb-v2', 'erimm-rgb', 'ekta-space-ps-5', 'f-gamut', 'filmlight-e-gamut', 'itu-r-bt2020', 'itu-r-bt470-525', 'itu-r-bt470-625', 'itu-r-bt709', 'max-rgb', 'n-gamut', 'ntsc-1953', 'ntsc-1987', 'p3-d65', 'palsecam', 'prophoto-rgb', 'protune-native', 'redwidegamutrgb', 'redcolor', 'redcolor2', 'redcolor3', 'redcolor4', 'rimm-rgb', 'romm-rgb', 'russell-rgb', 's-gamut', 's-gamut3', 's-gamut3cine', 'smpte-240m', 'smpte-c', 'sharp-rgb', 'v-gamut', 'venice-s-gamut3', 'venice-s-gamut3cine', 'xtreme-rgb', 'srgb', 'aces', 'adobe1998', 'prophoto']
>>> list(colour.RGB_COLOURSPACES.canonical_keys())
['aces20651', 'acescc', 'acescct', 'acescg', 'acesproxy', 'adobergb1998', 'adobewidegamutrgb', 'applergb', 'bestrgb', 'betargb', 'blackmagicwidegamut', 'ciergb', 'cinemagamut', 'colormatchrgb', 'dcdmxyz', 'dcip3', 'dcip3p', 'djidgamut', 'dragoncolor', 'dragoncolor2', 'davinciwidegamut', 'displayp3', 'donrgb4', 'ecirgbv2', 'erimmrgb', 'ektaspaceps5', 'fgamut', 'filmlightegamut', 'iturbt2020', 'iturbt470525', 'iturbt470625', 'iturbt709', 'maxrgb', 'ngamut', 'ntsc1953', 'ntsc1987', 'p3d65', 'palsecam', 'prophotorgb', 'protunenative', 'redwidegamutrgb', 'redcolor', 'redcolor2', 'redcolor3', 'redcolor4', 'rimmrgb', 'rommrgb', 'russellrgb', 'sgamut', 'sgamut3', 'sgamut3cine', 'smpte240m', 'smptec', 'sharprgb', 'vgamut', 'venicesgamut3', 'venicesgamut3cine', 'xtremergb', 'srgb', 'aces', 'adobe1998', 'prophoto']
>>> list(colour.MSDS_CMFS.slugified_keys())
['stockman-sharpe-2-degree-cone-fundamentals', 'stockman-sharpe-10-degree-cone-fundamentals', 'smith-pokorny-1975-normal-trichromats', 'wright-guild-1931-2-degree-rgb-cmfs', 'stiles-burch-1955-2-degree-rgb-cmfs', 'stiles-burch-1959-10-degree-rgb-cmfs', 'cie-1931-2-degree-standard-observer', 'cie-1964-10-degree-standard-observer', 'cie-2012-2-degree-standard-observer', 'cie-2012-10-degree-standard-observer', 'cie-2015-2-degree-standard-observer', 'cie-2015-10-degree-standard-observer', 'cie_2_1931', 'cie_10_1964']
>>> list(colour.MSDS_CMFS.canonical_keys())
['stockmansharpe2degreeconefundamentals', 'stockmansharpe10degreeconefundamentals', 'smithpokorny1975normaltrichromats', 'wrightguild19312degreergbcmfs', 'stilesburch19552degreergbcmfs', 'stilesburch195910degreergbcmfs', 'cie19312degreestandardobserver', 'cie196410degreestandardobserver', 'cie20122degreestandardobserver', 'cie201210degreestandardobserver', 'cie20152degreestandardobserver', 'cie201510degreestandardobserver', 'cie21931', 'cie101964']

Most of the datasets Colour ship with benefit from this new feature.

Performance

• colour.temperature.uv_to_CCT_Ohno2013 definition is ~100x faster. (#951, @KelSolaar)
• colour.temperature.CCT_to_uv_Ohno2013 definition is ~425x faster. (#951, @KelSolaar)
• Creation of the colour.Signal class underlying continuous function now happens lazilly. (#1057, @tjdcs)
• colour.SpectralDistribution.shape property getter is faster by ensuring monotonicity of the colour.SpectralDistribution.domain property. (#1067, 85f6a57, @tjdcs, @KelSolaar)

Fixes

colour.contrast

• Fix incorrect log function in the pupil diameter computation of Barten (1999) contrast sensitivity function. (#1022, @xmsguan, @KelSolaar)

Changes

colour.algebra

colour.characterisation

Object | Signature ...

Colour 0.4.1 - Alpha Milestone

This release is a maintenance release that mainly addresses packaging issues experienced by the MSYS2 maintainers and import issues when using Colour with Numpy 1.19.x and 1.20.x.

Fixes

Dependencies

• Fix import issues when trying to import colour with Numpy 1.19.x and 1.20.x. (@KelSolaar, @remia)

Distribution

• Fix incorrectly generated setup.py file. (@KelSolaar, @kmilos)

colour.colorimetry

• Fix intersection filtering in colour.colorimetry.closest_spectral_locus_wavelength definition. (@KelSolaar, @sobotka)

Colour 0.4.0 - Alpha Milestone

Over a year in the making, this release integrates most of the GSoC 2021 work from Cédric (@villirion), all the code from Geetansh (@SGeetansh) and the remaining GSoC 2020 code from Nishant (@njwardhan). We would like to thank them again for their great contributions!

Python 2.7 support has been dropped and the minimal version is Python 3.8 as per https://scientific-python.org/. The following minimal dependency versions are also required:

• imageio >= 2, < 3
• numpy >= 1.19, < 2
• scipy >= 1.5, < 2

The highlights of this release are as follows:

• Colour now runs on iOS and iPadOS with Pyto.
• The import of colour is now 3.6 times faster.
• Typing annotations have been added and the codebase is checked with Mypy.
• The documentation has been updated and uses the pydata-sphinx-theme and has better compliance with PEP257.
• The code formatter is now Black,
• Many Python 3 features such as f-Strings or the dataclass decorator have been adopted.
• The plotting API has been improved to be more consistent when setting the colours of some figures, e.g. spectral or planckian locus.
• New colour appearance models:
  • Zhai and Luo (2018) chromatic adaptation model.
  • Kim, Weyrich and Kautz (2009) colour appearance model.
  • ZCAM colour appearance model.
  • Helmholtz-Kohlrausch effect estimation.
• New colour models:
  • Oklab colour model.
  • Hanbury (2003) IHLS (Improved HLS) colourspace.
  • DIN99b, DIN99c, and DIN99d refined formulas.
  • ProLab colourspace.
  • Sarifuddin and Missaoui (2005) HCL colourspace.
• New RGB colourspaces and transfer functions:
  • Nikon N-Gamut colourspace and the N-Log log encoding.
  • Blackmagic Wide Gamut colourspace and the associated Blackmagic Film Generation 5 OETF.
  • DaVinci Intermediate OETF.
  • RED Log3G10 encoding and decoding curves with linear extension.
• Other notable features:
  • Huang et al. (2015) power-functions.
  • LUT 1D, LUT 3x1D and LUT 3D inversion.
  • UPRTek and Sekonic spectral data parsers.
  • SPImtx LUT input and output.
  • R'G'B' to Y'CbCr matrices computation.
  • Gamut ring/section plotting.
  • Rösch-MacAdam colour solid hue lines.
  • Support for OpenColorIO processor.
    • Note that the optional dependency is not specified in the pyproject.toml, see AcademySoftwareFoundation/OpenColorIO#1573 for more information.

Thanks again to all the contributors to this release!

• @aforsythe
• @fredsavoir
• @ilia3101
• @jedypod
• @JGoldstone
• @nick-shaw
• @njwardhan
• @Paul-Sims
• @ramparvathaneni
• @romanovar
• @saransh
• @SGeetansh
• @sobotka
• @villirion
• @zachlewis

Features

Typing

• The API has been fully annotated with typing annotations, a new colour.hints sub-package exporting all the hints has been created.

Performance

• Import time has been reduced to ~1.5secs from 5.5secs on @KelSolaar's MacBook Pro (Retina, 13-inch, Mid 2014) by using a lazy load mechanism for the spectral data and delaying various imports in the colour.plotting.tm3018 module. See PR #840 for more information.
• Repetitive spectral computations are now cached and a small cache management API has been created, see colour.utilities.CACHE_REGISTRY attribute for more information.
• The colour.sd_to_XYZ and colour.msds_to_XYZ definitions now use the same n-dimensional code under the hood. Some minor numerical differences are expected as the explicit summations and multiplications have been replaced with np.dot.

colour.adaptation

GSoC - 2021

• Implement support for Zhai and Luo (2018) chromatic adaptation model with colour.adaptation.chromatic_adaptation_Zhai2018 definition. (@villirion, @KelSolaar)

colour.appearance

GSoC - 2021

• Implement support for Kim, Weyrich and Kautz (2009) colour appearance model with colour.XYZ_to_Kim2009 and colour.Kim2009_to_XYZ definitions. (@villirion, @KelSolaar)

• Implement support for ZCAM colour appearance model with the colour.XYZ_to_ZCAM and colour.ZCAM_to_XYZ definitions. (@KelSolaar)
• Implement support for Helmholtz-Kohlrausch effect estimation with colour.HelmholtzKohlrausch_effect_object_Nayatani1997 and colour.HelmholtzKohlrausch_effect_luminous_Nayatani1997 definitions. (@ilia3101, @KelSolaar)
• Colour appearance models now use a dataclass-like class output instead of the namedtuple and thus are mutable.

colour.characterisation

• Various ACES Input Device Transform computation objects have been updated to generate additional data and support more features for the Academy Input Device Transform (IDT) calculator. (@KelSolaar, @aforsythe)
• Add colour.camera_RGB_to_ACES2065_1 definition. (@KelSolaar, @aforsythe)

colour.colorimetry

• Implement support for spectral uniformity computation with colour.spectral_uniformity definition. (@KelSolaar)
• Add colour.TVS_ILLUMINANTS attribute providing a reference for the CIE XYZ tristimulus values of the CIE illuminants. (@KelSolaar)
• Ensure that colour.SpectralShape and dict KeysView class instances can be passed as domain to colour.SpectralDistribution and colour.MutliSpectralDistributions classes. (@KelSolaar)
• The colour.colorimetry.yellowness_ASTME313 definition has been updated to use the recommended Yellowness Index equation as given by ASTME313. The alternative method has been renamed to colour.colorimetry.yellowness_ASTME313_alternative. (@KelSolaar, @romanovar)

colour.difference

• Implement support for STRESS index computation according to García et al. (2007) method with colour.index_stress definition and colour.INDEX_STRESS_METHODS attribute. (@KelSolaar)
• Implement support for Huang et al. (2015) power-functions improving colour-difference formulas with colour.difference.power_function_Huang2015 definition. (@KelSolaar)

colour.io

GSoC - 2020

• Implement support for LUT 1D, LUT 3x1D and LUT 3D inversion with the colour.LUT1D.invert, colour.LUT3x1D.invert and colour.LUT3D.invert methods. (@njwardhan, @KelSolaar)

GSoC - 2021

• Implement support for UPRTek and Sekonic spectral data parsers with the colour.SpectralDistribution_UPRTek and colour.SpectralDistribution_Sekonic classes. (@SGeetansh, @KelSolaar)

• Implement support for OpenColorIO processor with colour.io.process_image_OpenColorIO definition. (@KelSolaar)
• Implement support for SPImtx LUT input and output with new colour.io.read_LUT_SonySPImtx and colour.io.write_LUT_SonySPImtx definitions and colour.io.LUTOperatorMatrix support class. (@nick-shaw, @KelSolaar, @zachlewis)
• The colour.io.tm2714.Header_IESTM2714 class can now be hashed and compared for equality. (@JGoldstone)

colour.models

GSoC - 2021

• Implement support for Hanbury (2003) IHLS (Improved HLS) colourspace with colour.RGB_to_IHLS and colour.IHLS_to_RGB definitions. (@SGeetansh, @KelSolaar)
• Implement support for DIN99b, DIN99c, and DIN99d refined formulas in colour.Lab_to_DIN99 and colour.DIN99_to_Lab definitions. (@SGeetansh)
• Implement support for ProLab colourspace with colour.ProLab_to_XYZ and colour.XYZ_to_ProLab definitions. (@SGeetansh, @KelSolaar)

• Implement support for Sarifuddin and Missaoui (2005) HCL colourspace with colour.RGB_to_HCL and colour.HCL_to_RGB definitions. (@Saransh-cpp, @KelSolaar)
• Implement wrapper colour.XYZ_to_ICTCP and colour.ICTCP_to_XYZ definitions. (@KelSolaar)
• Implement wrapper colour.XYZ_to_CAM02LCD, colour.CAM02LCD_to_XYZ, colour.XYZ_to_CAM02SCD, colour.CAM02SCD_to_XYZ, colour.XYZ_to_CAM02UCS and
  colour.CAM02UCS_to_XYZ definitions. (@KelSolaar)
• Implement wrapper colour.XYZ_to_CAM16LCD, colour.CAM16LCD_to_XYZ, colour.XYZ_to_CAM16SCD, colour.CAM16SCD_to_XYZ, colour.XYZ_to_CAM16UCS and
  colour.CAM16UCS_to_XYZ definitions. (@KelSolaar)
• Implement support for R'G'B' to Y'CbCr matrices computation with colour.matrix_YCbCr and colour.offset_YCbCr definitions. (@KelSolaar, @nick-shaw)
• Implement support for Oklab colour model with colour.XYZ_to_Oklab and colour.Oklab_to_XYZ definitions. (@KelSolaar)
• Implement support for Nikon N-Gamut colourspace and the N-Log log encoding and decoding curves with colour.models.RGB_COLOURSPACE_N_GAMUT class and colour.models.log_encoding_NLOG and colour.models.log_decoding_NLOG definitions. (@sobotka, @KelSolaar)
• Implement support for RED Log3G10 encoding and decoding curves that uses a linear extension as given in the final version of White Paper on REDWideGamutRGB and Log3G10. (@jedypod)
• Implement support for Blackmagic Wide Gamut colourspace and the associated Blackmagic Film Generation 5 OETF and its inverse with colour.models.RGB_COLOURSPACE_BLACKMAGIC_WIDE_GAMUT attribute, colour.models.oetf_BlackmagicFilmGeneration5 and colour.models.oetf_inverse_BlackmagicFilmGeneration5 definitions. (@KelSolaar)
• Implement support for *DaVinci Inte...

Colour 0.3.16 - Alpha Milestone

This release integrates all the GSoC work from Pawel (@enneract), most of the code from Nishant (@njwardhan) and, the optimizations from Omar (@OmarWagih1). We would like to thank them again for their great contributions!

We stop testing for Python 3.5 and, Scipy>=1.1.0 becomes the minimum version. This is the last feature release to support Python 2.7! We will also trim the deprecation code in the next version thus, please make sure to update your code accordingly.

The colour.SpectralDistribution.interpolate and colour.MultiSpectralDistributions.interpolate methods now honour class instantiation time interpolation parameters instead of blindly applying CIE 167:2005 recommendation, this introduces minor numerical changes.

Many definitions, methods and, module attributes have been renamed to improve consistency and we are reaching a satisfactory point in that regard, hopefully, the names will be much more stable from now on.

Features

colour.algebra

• Add colour.algebra.smoothstep definition. (@KelSolaar)

colour.characterisation

• Support for ACES Input Device Transform (IDT) generation: The implementation follows to some extent RAW to ACES v1 and P-2013-001 procedure. (@KelSolaar)

Usage is simple and as follows:

>>> sensitivities = colour.CAMERA_RGB_SPECTRAL_SENSITIVITIES['Nikon 5100 (NPL)']
>>> illuminant = colour.ILLUMINANT_SDS['D55']
>>> colour.matrix_idt(sensitivities, illuminant)
array([[ 0.46579991,  0.13409239,  0.01935141],
       [ 0.01786094,  0.77557292, -0.16775555],
       [ 0.03458652, -0.16152926,  0.74270359]])

The following ISO 7589 and 6728 spectral data has been added: (@KelSolaar)

• ISO 6728 Standard Lens

• ISO 7589 Diffuser

• New attributes colour.SDS_LENSES containing the ISO 6728 Standard Lens and colour.SDS_FILTERScontaining the ISO 7589 Diffuser have been added.

• The ISO 17321-1 24 patches reflectance data has been added as an alias to Ohta (1997) measurements. (@KelSolaar)

colour.colorimetry

The following ISO 7589 illuminants have been added: (@KelSolaar)

• ISO 7589 Photographic Daylight

• ISO 7589 Sensitometric Daylight

• ISO 7589 Studio Tungsten

• ISO 7589 Sensitometric Studio Tungsten

• ISO 7589 Photoflood

• ISO 7589 Sensitometric Photoflood

• ISO 7589 Sensitometric Printer

• Add colour.msds_constant, colour.msds_zeros and colour.msds_ones definitions. (@KelSolaar)

colour.difference

• Add colour.difference.JND_CIE1976 attribute representing the Just Noticeable Difference (JND) according to CIE 1976 colour difference formula.

colour.geometry

The geometry primitives generation code has been consolidated into a new colour.geometry sub-package. The following objects are available: (@KelSolaar)

Primitives

• colour.geometry.primitive_grid
• colour.geometry.primitive_cube
• colour.PRIMITIVE_METHODS
• colour.primitive

Primitives Vertices

• colour.geometry.primitive_vertices_quad_mpl (for Matplotlib usage only)
• colour.geometry.primitive_vertices_grid_mpl (for Matplotlib usage only)
• colour.geometry.primitive_vertices_cube_mpl (for Matplotlib usage only)
• colour.geometry.primitive_vertices_sphere
• colour.PRIMITIVE_VERTICES_METHODS
• colour.primitive_vertices

colour.models

GSoC - 2020

• Add colour.models.log_encoding_Log2 and colour.models.log_decoding_Log2 log encoding and decoding definitions. (@njwardhan, @KelSolaar)
• Add colour.models.exponent_function_basic and colour.models.exponent_function_monitor_curve definitions. (@njwardhan)
• Add colour.models.logarithmic_function_basic, colour.models.logarithmic_function_quasilog and colour.models.logarithmic_function_camera definitions. (@njwardhan, @nick-shaw, @KelSolaar)

• Implement support for IGPGTG colourspace by Hellwig and Fairchild (2020) with the colour.XYZ_to_IGPGTG and colour.IGPGTG_to_XYZ definitions. (@KelSolaar)
• Implement support for DaVinci Wide Gamut colourspace. (@KelSolaar)

colour.plotting

• Implement support for ANSI/IES TM-30-18 Colour Rendition Report. (@enneract, @KelSolaar)

• Implement support for RGB colourspaces chromatic adaptation in various plotting routines: (@KelSolaar)

colour.quality

GSoC - 2020

• Implement support for CIE 2017 Colour Fidelity Index quality metric computation colour.quality.colour_fidelity_index_CIE2017 definition. (@enneract)
• Implement support for ANSI/IES TM-30-18 Colour Fidelity Index quality metric computation colour.quality.colour_fidelity_index_ANSIIESTM3018 definition. (@enneract)

colour.recovery

GSoC - 2020

• Implement support for Jakob and Hanika (2019) spectral upsampling method with the colour.recovery.XYZ_to_sd_Jakob2019 definition. (@enneract, @KelSolaar)
• Implement support for Mallett and Yuksel (2019) spectral upsampling method with the colour.recovery.RGB_to_sd_Mallett2019 definition. (@enneract)
• Implement support for Otsu, Yamamoto and Hachisuka (2018) spectral upsampling method with the colour.recovery.XYZ_to_sd_Otsu2018 definition. (@enneract, @KelSolaar)

colour.utilities

• Float precision can be set globally with the colour.utilities.set_float_precision definition and the COLOUR_SCIENCE__FLOAT_PRECISION environment variable. It will affect almost the entire API and lead to increase performance at the price of broken capabilities. (@KelSolaar)
• It is now possible to pass an axis argument to the colour.utilities.metric_mse and colour.utilities.metric_psnr definitions. (@KelSolaar)
• Add colour.utilities.LazyCaseInsensitiveMapping class for lazily loading slow and heavy datasets. (@KelSolaar)

Fixes

colour.characterisation

• The Finlayson, MacKiewicz and Hurlbert (2015) colour correction method was defective when root-polynomial expansion is in use. (@ChunHsinWang, @KelSolaar)

colour.colorimetry

• The colour.SpectralDistribution.align, colour.MultiSpectralDistributions.align, colour.SpectralDistribution.interpolate and colour.MultiSpectralDistributions.interpolate methods did not honour the instantiation time interpolation class and were forcibly using either the colour.SpragueInterpolator or colour.CubicSplineInterpolator classes unless an interpolator argument was passed. This behaviour was not desirable and was changed so that if the instantiation time interpolation class is not one of colour.SpragueInterpolator or colour.CubicSplineInterpolator, then, it will be used instead and thus it will take precedence over the CIE 167:2005 recommendation. (@KelSolaar)

The immediate consequence is small numerical changes to various spectral computations, for example:

     >>> illuminant = ILLUMINANTS_SDS['D65']
     >>> sd_to_XYZ_tristimulus_weighting_factors_ASTME308(
     ...     sd, cmfs, illuminant)  # doctest: +ELLIPSIS
-    array([ 10.8402899...,   9.6843539...,   6.2160858...])
+    array([ 10.8405832...,   9.6844909...,   6.2155622...])
     >>> from colour import COLOURCHECKERS_SDS
     >>> sd = COLOURCHECKERS_SDS['ColorChecker N Ohta']['dark skin']
     >>> sd_to_aces_relative_exposure_values(sd)  # doctest: +ELLIPSIS
-    array([ 0.1171785...,  0.0866347...,  0.0589707...])
+    array([ 0.1171814...,  0.0866360...,  0.0589726...])

Colour quality metrics are affected a bit more severely:

```diff
     >>> from colour import ILLUMINANTS_SDS
     >>> sd = ILLUMINANTS_SDS['FL2']
     >>> colour_rendering_index(sd)  # doctest: +ELLIPSIS
-    64.1515202...
+    64.2337241...
     >>> from colour import ILLUMINANTS_SDS
     >>> sd = ILLUMINANTS_SDS['FL2']
     >>> colour_quality_scale(sd)  # doctest: +ELLIPSIS
-    64.0172835...
+    64.1117031...

CIE Illuminant D Series D60 chromaticity have also been modified:

-    'D60': np.array([0.321626242047397, 0.337736995955436]),
+    'D60': np.array([0.321616709705268, 0.337619916550817]),

See #566 for more details.

colour.models

• colour.OETF_INVERSES attribute ITU-R BT.2100 HLG key was incorrectly named ITU-R BT.2100 HLD. (@jchwei)
• colour.HSL_to_RGB definition output was incorrect when saturation was equal to 1. (@KelSolaar, @nadersadoughi)

colour.plotting

• The colour.plotting.diagrams.plot_chromaticity_diagram definition was not passing anymore the CMFS to the underlying colour.plotting.diagrams.plot_spectral_locus and colour.plotting.diagrams.plot_chromaticity_diagram_colours definitions. (@KelSolaar, @sobotka)

colour.utilities

• The colour.utilities.filter_warnings definition was not behaving properly and has been fixed. (@KelSolaar)

Examples

• colour.plotting.plot_RGB_colourspaces_gamuts definition was using an incorrect style argument. (@sianyi)

C...

Colour 0.3.15 - Alpha Milestone

This is mainly a maintenance release implementing support for Python 3.8, Numpy 1.18 and fixing a major issue in Krystek (1985) correlated colour temperature computation.

Features

colour.colorimetry

• The typical CIE LED illuminants spectral power distributions and chromaticity coordinates have been added to the datasets: (@KelSolaar)
  • LED-B1
  • LED-B2
  • LED-B3
  • LED-B4
  • LED-B5
  • LED-BH1,
  • LED-RGB1
  • LED-V1
  • LED-V2
• The recommended indoor illuminants ID65 and ID50 spectral power distributions and chromaticity coordinates have been added to the datasets. (@KelSolaar)
• Add colour.colorimetry.sds_and_multi_sds_to_multi_sds definition that converts given spectral and multi-spectral distributions to multi-spectral distributions. (@KelSolaar)

colour.models

• Implement support for Display P3 RGB colourspace as per https://developer.apple.com/documentation/coregraphics/cgcolorspace/1408916-displayp3#discussion. (@sobotka)
• Add colour.models.Jab_to_JCh and colour.models.JCh_to_Jab definitions. (@KelSolaar)

Fixes

colour

Various fixes have been implemented to ensure compatibility with Python 3.8 and Numpy 1.18. (@KelSolaar, @MaxSchambach, @mzszym)

colour.io

• Prevent spi3d LUT index duplicates because of floating point precision related issues. (@KelSolaar, @sobotka, @nick-shaw)

colour.notation

• Fix incorrect Domain-Range scale in Munsell Renotation System implementation. (@KelSolaar)

colour.temperature

• colour.temperature.CCT_to_uv_Krystek1985 definition was incorrectly implemented. Incorrect reading of the reference publications ended up with exponentiations being different, e.g. 10**4 was replaced with 10e4. (@OlliNiemitalo)

Changes

colour.algebra

• colour.algebra.cartesian_to_spherical and colour.algebra.spherical_to_cartesian use ISO conversion convention. ρ is in range [0, +inf], θ is in range [0, pi] radians, i.e. [0, 180] degrees, and φ is in range [-pi, pi] radians, i.e. [-180, 180] degrees.

colour.volume

• colour.is_within_visible_spectrum: (@KelSolaar)
  • Signature: XYZ_outer_surface(XYZ, cmfs=STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].clone().align(DEFAULT_SPECTRAL_SHAPE_XYZ_OUTER_SURFACE), illuminant=sd_ones(DEFAULT_SPECTRAL_SHAPE_XYZ_OUTER_SURFACE), tolerance=None, **kwargs)
• colour.volume.XYZ_outer_surface: (@KelSolaar)
  • Signature: XYZ_outer_surface(cmfs=STANDARD_OBSERVERS_CMFS['CIE 1931 2 Degree Standard Observer'].clone().align(DEFAULT_SPECTRAL_SHAPE_XYZ_OUTER_SURFACE), illuminant=sd_ones(DEFAULT_SPECTRAL_SHAPE_XYZ_OUTER_SURFACE), **kwargs)
  • Implementation: The generated CIE XYZ tristimulus values are not normalised anymore, this will only affect computation if a different illuminant than CIE Illuminant E is chosen.

colour.plotting

• colour.plotting.common.wrap_title: (@KelSolaar)
  • Remove