CS151.02 2010S Functional Problem Solving

Class 12: A Design Perspective

Back to Transforming Colors. On to Transforming Images.

This outline is also available in PDF.

Held: Friday, February 12, 2010

Summary: We consider the basics of color theory.

Related Pages:



Guest Lecture

Prof. Kluber's Notes

Matthew Kluber
Color Discussion

"The chief aim of color should be to serve expression as well as possible." Henri Matisse

Light and Color

In addition to vision the other element needed for us to see color is light. There are two kinds of light that allow us to see color. The first is incandescence; this light is produced by heated materials: the sun, fire, and tungsten light bulbs, for example. The second kind of light is luminescence; this light is the result of specific movements and emissions of electrons, producing light at a lower temperature than incandescence. Fireflies, fluorescent lights, televisions, computer monitors and lasers generate luminescent light. Both incandescence and luminescence produce white light, the light that makes up the visible spectrum of color.

Humans have long used pigments to create color. What we see as color in a painting on the wall of a cave or on a canvas is reflected light. Each pigment selectively absorbs, or subtracts, specific wavelengths of the visible spectrum and reflects the rest. The color red, for example, is red because when light hits its surface the pigment absorbs (subtracts) the entire visible spectrum except the red portion. This is subtractive color.

The kind of color you are creating and manipulating in this course is produced by luminescent light. Each pixel in your computer monitor combines red (R), green (G), and blue (B) lights. They can be added together to create virtually any color perceivable to the eye. When all three colors are added together in equal amounts the result is white. This is additive color – or simply RGB.

Some Principles of Color

The following are some terms and approaches used to teach artists and designers the fundamentals of color theory. As a general reference from an art and design perspective, I will use the subtractive color system here, with a few exceptions, these principles apply to additive color.

Hue: Hue simply refers to the name of the color. Red, green, orange, and purple, for example, are hues. However, there is a distinction between hue and color. One hue can be varied to produce many colors – there are relatively few hues, but there can be an unlimited number of colors. Pink, rose scarlet, maroon, and crimson are all colors, but the hue in each case is red.

Primary colors: The three primary colors are red, yellow, and blue. From these all other colors are mixed.

Secondary colors: The three secondary colors are mixtures of two primaries – orange, violet, and green. Because of the relative strength of the various hues, a visual middle secondary does not always contain equal amounts of the two colors.

Tertiary colors: The six tertiary colors are mixtures of a primary and an adjacent secondary – yellow-orange, red-orange, red-violet, blue-violet, and yellow-green.

Value: Value refers to the lightness or darkness of the color; value is altered by adding black or white to a color. Adding black darkens the color and produces a shade or low-value color. Adding white lightens the color, producing a tint or high-value color. Value, like color itself, is variable and entirely dependent on surrounding hues for its visual sensation. Most people can distinguish at least forty shades and tints of any color.

Intensity or saturation: Intensity refers to the brightness of a color – because a color is at full intensity only when pure and unmixed. Mixing black or white with a color changes its value, but also affects its intensity. There are two ways to lower the intensity of a color, to make a color less bright, more neutral. The first is to mix gray with the color. The second is to mix a color with its compliment – the color directly across from it on the color wheel. When not mixed, but placed side-by-side, complimentary colors intensify the visual brilliance of one another, so that the colors appear to vibrate.

Color Schemes

Complementary: A complementary color scheme joins contrasting colors that lie opposite each other on the color wheel.

Analogous: An analogous color scheme combines three colors that are adjacent to one another on the color wheel.

Monochromatic: A monochromatic color scheme involves the use of only one color. The color can vary in value and pure black or white may be added. The resulting effect is extremely harmonious, and generally quiet and subtle.

Cool and warm colors: Blue and green are thought of as cool colors with blue-green the coldest of hues. Red, yellow, and orange are thought of as warm colors with red-orange as the warmest color. Warm colors tend to advance while cool colors tend to recede. Warm/cool color relationships allow for establishing depth and volume in painting.

Color discord: Color discord is the opposite of color harmony. Colors widely separated on the color wheel (but not compliments) are generally seen as discordant combinations. A couple of examples: combining a primary and a tertiary that is beyond an adjacent secondary like red and blue-purple; combining a secondary and a tertiary beyond an adjacent primary like orange and yellow-green. It is important to note that the impression of discord is much greater when the value of the two colors is similar.

Color context: a color can appear to be different depending on the colors that surround it; the perception of it changes according to its context.

These principles serve a reference point for an informed exploration of color. With practice you will develop your own ability to articulate visual information with color. The articulate arrangement of visual information leads one not only to clear communication but to expression as well.

Some useful websites regarding color theory:

Back to Transforming Colors. On to Transforming Images.

Disclaimer: I usually create these pages on the fly, which means that I rarely proofread them and they may contain bad grammar and incorrect details. It also means that I tend to update them regularly (see the history for more details). Feel free to contact me with any suggestions for changes.

This document was generated by Siteweaver on Tue May 11 09:03:09 2010.
The source to the document was last modified on Thu Jan 21 13:05:15 2010.
This document may be found at http://www.cs.grinnell.edu/~rebelsky/Courses/CS151/2010S/Outlines/outline.12.html.

You may wish to validate this document's HTML ; Valid CSS! ; Creative Commons License

Samuel A. Rebelsky, rebelsky@grinnell.edu

Copyright © 2007-10 Janet Davis, Matthew Kluber, Samuel A. Rebelsky, and Jerod Weinman. (Selected materials copyright by John David Stone and Henry Walker and used by permission.) This material is based upon work partially supported by the National Science Foundation under Grant No. CCLI-0633090. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. This work is licensed under a Creative Commons Attribution-NonCommercial 2.5 License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc/2.5/ or send a letter to Creative Commons, 543 Howard Street, 5th Floor, San Francisco, California, 94105, USA.