Envisioning Information by Edward R Tufte
(Same author of famous book, 'The visual display of quantitative Information'.
The book is explaining how to represent rich visual world of experience and measurement in a paper(flatland). It is called 'cognitive art' by Philip Morrison. Mainly talking about importance of color combination in large data representations (e.g. maps, landscape etc)
Confusion and clutter are failures of design, not attributes of information. Among the most powerful devices for reducing noise and enriching the content of displays is the technique of layering and separation, visually stratifying various aspects of data.
The various elements collected together on flatland interact, creating non-information patterns and texture simply through their combined presence. Josef Alberts described this visual effect as 1*1=3. (e.g. keeping 5 pentagons each other in round, creates 6th pentagon inside).
Human eyes exquisitely sensitive to color variations: a trained colorist can distinguish among 1,000,000 colors; some 20,000 colors are accessible to many viewers.
The first rule of color composition : Pure, bright or very strong colors have loud, unbearable effects when they stand unrelieved over large areas adjacent to each other, but extraordinary effects can be achieved when they are sparingly on or between dull background tones. 'Noise is not music... only on a quite background can a colorful theme be constructed" - Windisch. If one limits strong, heavy, rich and solid colors to the small areas of extremes, then expressive and beautiful patterns occur. If one gives all, esp. large areas, glaring, rich colors, the picture have brilliant, disordered, confusing and unpleasant effects.
Second rule: The placing of light, bright colors mixed with white next to each other usually produces unpleasant results, esp. if the colors are used for large areas.
(color spots against a light gray or muted field highlight and italicize data, and also help to weave an overall harmony).
Third rule: Large area background or base-colors should do their work most quietly, allowing the smaller, bright areas to stand out most vividly, if the former are muted, grayish or neutral. For this very good reason, Grey is regarded in painting to be one of the prettiest, most important and most versatile of colors. Strongly muted colors, mixed with Grey, provide the best background for colored theme.
Fourth rule: If a picture is composed of two or more large, enclosed areas in different colors, then the picture falls apart. Unity will be maintained, however, if the colors of one area are repeatedly interrupted in the other, if the colors are interwoven carpet-fashion throughout the other. All colors of the main theme should be created like islands in the background color.