Lightness corresponds to how much light appears to be reflected from a surface in relation to nearby surfaces. Lightness, like hue, is a perceptual attribute that cannot be computed from physical measurements alone. It is the most important attribute in making contrast more effective. With color deficits, the ability to discriminate colors on the basis of lightness is reduced. Top of page Saturation is the degree of color intensity associated with a color's perceptual difference from a white, black or gray of equal lightness.
Slate blue is an example of a desaturated color because it is similar to gray.
A deep blue, even if it has the same lightness as slate blue, has greater saturation. Congenital and acquired color deficits typically make it difficult to discriminate between colors on the basis of saturation. Designers can help to compensate for these deficits by making colors differ more dramatically in all three attributes. Designing for People with Partial Sight. Dr. Arditi is an expert in vision science.