Black is used in the subtractive model as well, because cyan, magenta, and yellow make more of a dark gray than pure black when they are combined. In the Subtractive model, light reflected off a surface is what the surface doesn't absorb. Hue simply means the actual shade or color, saturation is just how pure the hue is, and luminance is what is described when we say that a color is either light or dark. Color Complements Complementing colors also have to be considered if you are seriously pondering color combinations. They highly contrast each other, and when placed side by side, enhance the color of the other.
Some people have trouble discerning colors, along with their shades and luminance.
Color blindness is a color perception problem whose most common ailment is a red-green deficiency. This is because the defect is linked to the X-chromosome, of which males only have one, so there is less chance of it being naturally corrected by the genes. Trace a ray of light from a point on a solid object to a light source. If the ray of light hits another object before you get to the light source, the point is in shadow . A shadow, present in an area where there is less light, must be opposite a light source.