Convert sRGB values to physically linear ones. The transformation is
    uniform in RGB, so *srgb* can be of any shape.

    *srgb* values should range between 0 and 1, inclusively.

def srgb_to_linsrgb (srgb):
    """Convert sRGB values to physically linear ones. The transformation is
    uniform in RGB, so *srgb* can be of any shape.

    *srgb* values should range between 0 and 1, inclusively.

    """
    gamma = ((srgb + 0.055) / 1.055)**2.4
    scale = srgb / 12.92
    return np.where (srgb > 0.04045, gamma, scale)