Last active
February 25, 2022 06:24
-
-
Save sobotka/b4da09b1445b4082e02b2481bc6ff666 to your computer and use it in GitHub Desktop.
Arri Wide Gamut to REC.709
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
| - !<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 :)
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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.