colour.recovery.RGB_to_sd_Mallett2019#

Recover the spectral distribution of the specified RGB colourspace array using Mallett and Yuksel (2019) method.

Parameters:

RGB (Annotated[_Buffer | _SupportsArray[dtype[Any]] | _NestedSequence[_SupportsArray[dtype[Any]]] | complex | bytes | str | _NestedSequence[complex | bytes | str], 1]) – RGB colourspace array.
basis_functions (MultiSpectralDistributions) – Basis functions for the method. The default is to use the built-in sRGB basis functions, i.e., colour.recovery.MSDS_BASIS_FUNCTIONS_sRGB_MALLETT2019.

Returns:

Recovered reflectance.

Return type:

colour.SpectralDistribution

References

[MY19]

Notes

Domain	Scale - Reference	Scale - 1
`RGB`	1	1

In addition to the BT.709 primaries used by the sRGB colourspace, [MY19] tested BT.2020, P3 D65, Adobe RGB 1998, NTSC (1987), Pal/Secam, ProPhoto RGB, and Adobe Wide Gamut RGB primaries, every one of which encompasses a larger (albeit not always enveloping) set of CIE L*a*b* colours than BT.709. Of these, only Pal/Secam produces a feasible basis, which is relatively unsurprising since it is very similar to BT.709, whereas the others are significantly larger.

Examples

>>> from colour import MSDS_CMFS, SDS_ILLUMINANTS, XYZ_to_sRGB
>>> from colour.colorimetry import sd_to_XYZ_integration
>>> from colour.recovery import SPECTRAL_SHAPE_sRGB_MALLETT2019
>>> from colour.utilities import numpy_print_options
>>> XYZ = np.array([0.20654008, 0.12197225, 0.05136952])
>>> RGB = XYZ_to_sRGB(XYZ, apply_cctf_encoding=False)
>>> cmfs = (
...     MSDS_CMFS["CIE 1931 2 Degree Standard Observer"]
...     .copy()
...     .align(SPECTRAL_SHAPE_sRGB_MALLETT2019)
... )
>>> illuminant = SDS_ILLUMINANTS["D65"].copy().align(cmfs.shape)
>>> sd = RGB_to_sd_Mallett2019(RGB)
>>> with numpy_print_options(suppress=True):
...     sd
SpectralDistribution([[380.        ,   0.1735531...],
                      [385.        ,   0.1720357...],
                      [390.        ,   0.1677721...],
                      [395.        ,   0.1576605...],
                      [400.        ,   0.1372829...],
                      [405.        ,   0.1170849...],
                      [410.        ,   0.0895694...],
                      [415.        ,   0.0706232...],
                      [420.        ,   0.0585765...],
                      [425.        ,   0.0523959...],
                      [430.        ,   0.0497598...],
                      [435.        ,   0.0476057...],
                      [440.        ,   0.0465079...],
                      [445.        ,   0.0460337...],
                      [450.        ,   0.0455839...],
                      [455.        ,   0.0452872...],
                      [460.        ,   0.0450981...],
                      [465.        ,   0.0448895...],
                      [470.        ,   0.0449257...],
                      [475.        ,   0.0448987...],
                      [480.        ,   0.0446834...],
                      [485.        ,   0.0441372...],
                      [490.        ,   0.0417137...],
                      [495.        ,   0.0373832...],
                      [500.        ,   0.0357657...],
                      [505.        ,   0.0348263...],
                      [510.        ,   0.0341953...],
                      [515.        ,   0.0337683...],
                      [520.        ,   0.0334979...],
                      [525.        ,   0.0332991...],
                      [530.        ,   0.0331909...],
                      [535.        ,   0.0332181...],
                      [540.        ,   0.0333387...],
                      [545.        ,   0.0334970...],
                      [550.        ,   0.0337381...],
                      [555.        ,   0.0341847...],
                      [560.        ,   0.0346447...],
                      [565.        ,   0.0353993...],
                      [570.        ,   0.0367367...],
                      [575.        ,   0.0392007...],
                      [580.        ,   0.0445902...],
                      [585.        ,   0.0625633...],
                      [590.        ,   0.2965381...],
                      [595.        ,   0.4215576...],
                      [600.        ,   0.4347139...],
                      [605.        ,   0.4385134...],
                      [610.        ,   0.4385184...],
                      [615.        ,   0.4385249...],
                      [620.        ,   0.4374694...],
                      [625.        ,   0.4384672...],
                      [630.        ,   0.4368251...],
                      [635.        ,   0.4340867...],
                      [640.        ,   0.4303219...],
                      [645.        ,   0.4243257...],
                      [650.        ,   0.4159482...],
                      [655.        ,   0.4057443...],
                      [660.        ,   0.3919874...],
                      [665.        ,   0.3742784...],
                      [670.        ,   0.3518421...],
                      [675.        ,   0.3240127...],
                      [680.        ,   0.2955145...],
                      [685.        ,   0.2625658...],
                      [690.        ,   0.2343423...],
                      [695.        ,   0.2174830...],
                      [700.        ,   0.2060461...],
                      [705.        ,   0.1977437...],
                      [710.        ,   0.1916846...],
                      [715.        ,   0.1861020...],
                      [720.        ,   0.1823908...],
                      [725.        ,   0.1807923...],
                      [730.        ,   0.1795571...],
                      [735.        ,   0.1785623...],
                      [740.        ,   0.1775758...],
                      [745.        ,   0.1771614...],
                      [750.        ,   0.1767431...],
                      [755.        ,   0.1764319...],
                      [760.        ,   0.1762597...],
                      [765.        ,   0.1762209...],
                      [770.        ,   0.1761803...],
                      [775.        ,   0.1761195...],
                      [780.        ,   0.1760763...]],
                     SpragueInterpolator,
                     {},
                     Extrapolator,
                     {'method': 'Constant', 'left': None, 'right': None})
>>> sd_to_XYZ_integration(sd, cmfs, illuminant) / 100
...
array([0.2065436..., 0.1219996..., 0.0513764...])

colour.recovery.RGB_to_sd_Mallett2019#

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