EOS C700 - Primaries Derivation

eos_c700_primaries_derivation.py

# IDT.Canon.EOSC700_CanonLog_CinemaGamut_TypeC_D55.a1.v1.ctl

import numpy as np
import colour

EOSC700_CINEMAGAMUT_TO_ACES_2065_1 = np.array(
    [[0.763064455, 0.149021161, 0.087914384],
     [0.003657457, 1.10696038, -0.110617837],
     [-0.009407794, - 0.218383305, 1.227791099]])

EOS_CINEMAGAMUT_TO_ACES_2065_1_MATRICES = {
    'EOS C700': EOSC700_CINEMAGAMUT_TO_ACES_2065_1}


def RGB_to_RGB_matrix_to_normalised_primary_matrix(RGB_to_RGB_matrix,
                                                   XYZ_to_RGB_matrix):
    M = np.einsum('...ij,...jk->...ik', RGB_to_RGB_matrix, XYZ_to_RGB_matrix)

    M = np.linalg.inv(M)

    return M


def EOS_CinemaGamut_colourspaces_derivation():
    EOS_CinemaGamut_colourspaces = {}
    for name, RGB_to_RGB_matrix in EOS_CINEMAGAMUT_TO_ACES_2065_1_MATRICES.items():
        NPM = RGB_to_RGB_matrix_to_normalised_primary_matrix(
            np.linalg.inv(RGB_to_RGB_matrix),
            colour.RGB_COLOURSPACES['ACES2065-1'].XYZ_to_RGB_matrix)

        P, W = colour.primaries_whitepoint(NPM)

        EOS_CinemaGamut_colourspaces[name] = colour.RGB_Colourspace(
            name,
            primaries=P,
            whitepoint=W,
            illuminant='D60',
            RGB_to_XYZ_matrix=NPM,
            XYZ_to_RGB_matrix=np.linalg.inv(NPM))
    return EOS_CinemaGamut_colourspaces


EOS_CINEMAGAMUT_COLOURSPACES = EOS_CinemaGamut_colourspaces_derivation()
print(EOS_CINEMAGAMUT_COLOURSPACES['EOS C700'].primaries)

# [[ 0.73929471  0.2703585 ]
#  [ 0.17859991  1.09863146]
#  [ 0.07084927 -0.11732917]]