sRGB.py

import numpy

XYZ_to_sRGB_matrix = \
    numpy.array(
        [[3.2404542, -1.5371385, -0.4985314],
        [-0.9692660,  1.8760108,  0.0415560],
        [0.0556434, -0.2040259,  1.0572252]])

def apply_srgb_gamma(RGB):
    non_linear = []
    for v in RGB:
        if v <= 0.0031308:
            non_linear.append(v * 12.92)
        else:
            non_linear.append(1.055 * math.pow(v, 1 / 2.4) - 0.055)
    return non_linear

def XYZ_to_sRGB(XYZ, illuminant_XYZ):
    # first adapt the XYZ values to the sRGB Illuminant
    # find this method in colour-science.org
    adaptation_matrix = \
        chromatic_adaptation_matrix_VonKries(source_illuminant, D65_illuminant)
    XYZ_adapted = numpy.dot(adaptation_matrix, XYZ)

    # do the linear conversion into sRGB space
    sRGB_linear = numpy.dot(XYZ_to_sRGB_matrix, XYZ_adapted)

    # apply the non-linearity function
    sRGB = np.array(apply_srgb_gamma(sRGB_linear))
    return sRGB