Pseudocoloring is a widely used technique for presenting univariate map information on a graphic display system. This article divides the kinds of information available in maps into two classes. Metric (or value) information denotes the quantity stored at each point on the surface, and form information denotes the shape and structure of the surface. Theoretical principles are proposed to predict which color sequences will be effective at conveying value and form information respectively. According to this theory a scale that approximates the physical spectrum should be good at conveying metric information because of the reduced effects of simultaneous contrast. It should be poor at conveying form information, however, because the brain prefers from information to come through the lightness processing "luminance" channel. Conversely, a gray scale should be poor at conveying value information and good at conveying form information according to the same theory. These predictions are tested in a series of psychophysical experiment which test five color sequences. The results show that simultaneous contrast can be a major source of error when reading maps, but only partially confirm the form hypothesis. Guidelines are given, based on the theory, for designing color sequences to be effective in both conveying form and value information. An experimental color sequence is presented to illustrate these guidelines.
Ware REF divided the information available in images into metric or value information and form or shape information.
Color sequences for univariate maps: Theory, experiments and principles
IEEE Computer Graphics and Applications
Computer Science