Blue mountains are distant from us, and so cool colors seem to recede.
The concept of color temperature or warm and cool colors is important to artists yet often poorly understood. This page provides an in depth review of the topic.
Goethe provides the headnote because it was his observation in the Farbenlehre, which struck me as ridiculous when I first read it a decade ago, that launched me on my study of color and, by an arduous path, led to the page you are reading now.
I begin with the conventional wisdom about the attributes of warm vs. cool colors, then explain why the effects ascribed to warm colors are not caused by their hue or by optical problems with our eyes but by their typically higher lightness or chroma in comparison to other surface colors.
The earliest artistic applications warm and cool appear in the modeling of light in Baroque landscape painting. I argue that the perceptual origin of warm/cool contrasts lies in the mechanism our color vision uses to adapt to changes in the color of natural illumination due to weather and time of day effects that are most obvious in landscape observation.
I develop a definition of "warm" color in paints, define the warm/cool contrast using three reflectance criteria, and finally show how these criteria are related to different hues around the hue circle. Finally, I show how the phenomenon of unsaturated color zones, warm colors that appear only through luminance contrasts, arise because of the limited span of S cone sensitivity.
These elements of the warm/cool contrast can be summarized as guidelines for painting warm or cool, which depend primarily on whether the painting style is landscape or not, and representational or not. Each situation should use warm/cool color contrasts in a different way.
warm vs. cool colors
Let's begin at the beginning. The concept of a warm/cool color contrast seems to have entered the artistic vocabulary during the 18th century. The earliest attestation in the Oxford English Dictionary (1890) for an artistic usage of warm The canvas glow'd, beyond e'en Nature warm is from a poem by Oliver Goldsmith dated 1764. Cold (the original contrast adjective for warm) appears earlier, in an English translation of Cours de peinture par principes (1708) by the French art historian Roger de Piles.
Warm and cold were, with dry and moist, terms used from the Middle Ages through the 18th century to describe a variety of animal and physical qualities. Warm described animation, exertion, ardent feeling or a complexion glowing with fever; cold described a lack of enthusiasm, sociability, life force or energy. There was a long tradition of metaphorical "warmth" from which the artistic usage grew.
Although the warm/cool contrast was familiar to artists since at least the early 18th century, it was to my knowledge first presented within a color wheel by the English artist Charles Hayter, in his Introduction to Perspective (1813). This shows that pairs of colors opposite each other on the hue circle are complementary colors, and that the warm/cool contrast is a "metacomplementary" relationship "the mother of all complementaries" between warm hues (from yellow to red violet) as a group and the cool hues (from yellow green to purple) as a group.
the first warm/cool color wheel diagram
from Hayter, 1813 (sky blue is placed at top, because in Hayter's time it was defined as the "purest" or most fundamental color; note the 19th century contrast with cold rather than cool)
Whenever you see a tidy geometrical icon in color theory writings, you can be sure that it represents something well cooked but only half baked! Despite the assurance and certainty expressed by Hayter's diagram, there are four questions that the traditional warm/cool usage has not clearly answered:
1. What are the warm (warmest) or cool (coolest) hues?
2. Is every hue in the color wheel either warm or cool, or are some hues excluded as neither warm nor cool?
3. What explains the visual or design effects created by warm or cool colors?
4. Why is the warm/cool contrast fundamental to our visual respo