import magicalrainbows.formats : RGB888; import std.math : approxEqual; assert(contrast(RGB888(0, 0, 0), RGB888(0, 0, 0)).approxEqual(1.0)); assert(contrast(RGB888(0, 0, 0), RGB888(255, 255, 255)).approxEqual(21.0)); assert(contrast(RGB888(255, 255, 255), RGB888(0, 0, 0)).approxEqual(21.0)); assert(contrast(RGB888(255, 255, 255), RGB888(250, 112, 20)).approxEqual(2.8407));