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Arri Wide Gamut to REC.709
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- !<ColorSpace> | |
name: Alexa Wide Gamut LogC | |
family: "" | |
equalitygroup: "" | |
bitdepth: 32f | |
description: | | |
LogC Arri Wide Gamut to REC.709 Primaries | |
isdata: false | |
allocation: uniform | |
allocationvars: [0, 1] | |
to_reference: !<GroupTransform> | |
children: | |
- !<FileTransform> {src: V3_LogC_800_to_linear.spi1d, interpolation: linear} | |
- !<MatrixTransform> {matrix: [0.638007619283725, 0.214703856337102, 0.097744451430844, 0, 0.291953778999716, 0.823841041510691, -0.115794820510407, 0, 0.00279827903194611, -0.0670342356889595, 1.15329370741689, 0, 0, 0, 0, 1]} | |
- !<MatrixTransform> {matrix: [0.41239079926596, 0.357584339383878, 0.180480788401834, 0, 0.21263900587151, 0.715168678767756, 0.0721923153607337, 0, 0.0193308187155918, 0.119194779794626, 0.950532152249661, 0, 0, 0, 0, 1], direction: inverse} |
But I got totally different matrices using colour science. Am I getting it wrong?
>>> matrix_RGB_to_RGB(colour.models.RGB_COLOURSPACE_sRGB, colour.models.RGB_COLOURSPACE_ALEXA_WIDE_GAMUT)
array([[ 0.63136262, 0.27081263, 0.09791522],
[ 0.03675345, 0.79307157, 0.17013495],
[ 0.01733878, 0.14879521, 0.8338121 ]])
>>> matrix_RGB_to_RGB(colour.models.RGB_COLOURSPACE_ALEXA_WIDE_GAMUT, colour.models.RGB_COLOURSPACE_sRGB)
array([[ 1.61734195, -0.53721545, -0.08028311],
[-0.07040252, 1.33455233, -0.26405072],
[-0.02106408, -0.22695949, 1.24809828]])
- AWG D65 -> XYZ
- XYZ -> sRGB D65
Got it. Thanks :)
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Previous incarnation had the transfer function encoded version from the Arri Vfx document. This uses the proper Arri Wide Gamut xyY chromaticity points to derive the XYZ matrix, and then uses the xyY coordinates of REC.709 to derive the destination matrix. The inverse direction is used here to keep the matrices legible in the forward RGB to XYZ direction.