Color appearance phenomena

Color constancy

The ability to identify consistent color of objects in varying lighting conditions.

Color constancy is identifying that the cast shadow is a pink surface, despite the actual color being purple. Color constancy is identifying that the cast shadow is a pink surface, despite the actual color being purple.

Examples

Checker shadow illusion

This illusion demonstrates an error in identification of a color's lightness due to surrounding colors. Squares A and B appear to be different, however they are the same color.

Illusion
 The gray squares (A) and (B) are the same, but appear to have different lightness.

"The dress"

This illusion is the result of improper color identification due to chromatic adaptation, or color constancy, and is known as "chromatic bias". Based on viewing conditions, or surrounding light, the dress may appear to be blue and black or white and gold.

Blue & black

How it affects UI design

Colors of different hue can be placed adjacently and appear to be objectively the same. Two-tone coloration of neo-brutalist buttons is a good example of this.

Sources:

  1. Mark D. Fairchild (2013). Color Appearance Models. 3rd edition. John Wiley & Sons, Ltd. Pages 26-27

    2. Pages 140 of this book literally say color constancy does not exist.