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)

Changes

colour.adaptation

colour.algebra

• The colour.algebra.cartesian_to_spherical and colour.algebra.spherical_to_cartesian definitions now use the ISO 31-11 parameterisation for consistency.

colour.appearance

colour.blindness

colour.characterisation

colour.colorimetry

• colour.sd_blackbody definition now returns values in W/sr/m^2/nm instead of W/sr/m^2/m. See #559 for more background information. (@KelSolaar, @Wagyx, @MichaelMauderer)
  colour.colorimetry
• colour.colorimetry.sd_CIE_illuminant_D_series definition return a spectral distribution whose name includes the used chromaticity coordinates and whose interpolator is instantiated from colour.algebra.LinearInterpolator. (@KelSolaar)

colour.constants

colour.continuous

colour.corresponding

colour.geometry

colour.io

colour.models

colour.notation

• The colour.notation.RGB_to_HEX definition will now clip negative values and the whole input array will be normalised to the maximum value if values over 1 are encountered. (@KelSolaar)

colour.plotting

colour.quality

colour.recovery

colour.temperature

colour.utilities

colour.volume