private static int scaleBrightness(int baseRgba, float brightness) {
            int r = (baseRgba >> 24) & 0xFF;
            int g = (baseRgba >> 16) & 0xFF;
            int b = (baseRgba >> 8) & 0xFF;
            int a = baseRgba & 0xFF;

            float[] hsb = new float[3];
            Color.RGBtoHSB(r, g, b, hsb);

            return Color.HSBtoRGB(hsb[0], hsb[1], brightness) << 8 | a;
        }
Colours used for Halo glow and bloom effects. They are traditional Minecraft
wool colours with scaled brightness components to reduce variation in
perceived brightness.
core/src/main/java/mrtjp/projectred/core/client/HaloRenderer.java