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.plotting

• colour.plotting.plot_multi_sds and colour.plotting.diagram.plot_sds_in_chromaticity_diagram definitions now default to use CIE Illuminant E when computing spectrum colours. (510860a, @KelSolaar)

colour.quality

• The colour.spectral_similarity_index definition has been updated to 2020 publication update. (#1163, @benjaminherb)