Shadery03_Saturation

half Grayscale(half3 c)
{
    return dot(c, half3(0.22, 0.707, 0.071));
}

half3 Saturation(half3 c, half saturation)
{
    half gray = Grayscale(c.rgb);
    c = lerp(fixed3(gray, gray, gray), c.rgb, saturation);
    return saturate(c);
}