import magicalrainbows.formats : RGB888; import std.math : isClose; assert(contrast(RGB888(0, 0, 0), RGB888(0, 0, 0)).isClose(1.0)); assert(contrast(RGB888(0, 0, 0), RGB888(255, 255, 255)).isClose(21.0)); assert(contrast(RGB888(255, 255, 255), RGB888(0, 0, 0)).isClose(21.0)); assert(contrast(RGB888(255, 255, 255), RGB888(250, 112, 20)).isClose(2.8406907130));