def white_lowering_function(gamma_corrected_luma):
    """
    White is not very important for this filter.
    """
    t = 0.7
    if gamma_corrected_luma > t:
        return gamma_corrected_luma - gamma_corrected_luma * 0.25 * ((
            gamma_corrected_luma - t) / (1 - t))
    else:
        return gamma_corrected_luma
