from the Art of Color by Johannes Itten
We speak of contrast when distinct differences can be perceived between two compared effects. When such differences attain their maximum degree, we speak of diametrical or polar contrasts. Thus, large-small, white-black, cold-warm, in their extremes, are polar contrasts. Our sense organs can function only by means of comparisons. The eye accepts a line as long when a shorter line is presented for comparison. The same line is taken as short when the line compared with it is longer. Color effects are similarly intensified or weakened by contrast.
When we survey the characteristics of color effect, we can detect seven different kinds of contrast. These are so different that each will have to be studied separately. Each is unique in character and artistic value, in visual, expressive, and symbolic effect; and together they constitute the fundamental resource of color design.
[...] a systematic and practical introduction to the special effects of color contrast, with exercises, has been lacking. Such an exploration of color contrasts is an essential part of my course of instruction.
The seven kinds of color contrasts are the following:
1. contrast of hue
2. light-dark contrast (value)
3. cold-warm contrast
4. complementary contrast
5. simultaneous contrast
6. contrast of saturation
7. contrast of extension (proportion)
Johannes Itten, The Art of Color
