color theory 101

via jim curran, infodesign-cafe:

very nice, concise explanation of the different color systems with great diagrams.

pigment primaries: red, yellow, blue
mixing pigments (ex. yellow + blue = green) produces different colors

additive primaries: red, green, blue
starting with a dark space you add colors of light (ex. blue + green = cyan) to create colors. adding the 3 primaries (re, green, blue) produces white

subtractive primaries: cyan, magenta, yellow
start with white light and use filters of color (ex. cyan filter removes red) to subtract it's oppostite color out. using all 3 filters of cyan, magenta, and yellow removes all light and produces black

When white light goes through cyan the red is subtracted out. When the white light goes through the magenta, green light is subtracted out. When the white light goes through the yellow, blue light is subtracted out and you end up with black. So cyan, magenta and yellow are the primary colors when dealing with subtractive light. When white light goes through magenta and yellow, it produces red. When it goes through cyan and yellow, it produces green. When white light goes through cyan and magenta, blue is produced. So the secondary primaries of the subtractive system are red, green and blue.

color spectrum:

follow-up thoughts from randal on infodesign-cafe:

ALSO -- it is imperative that students understand that the theory of the color wheel -- and its application in color printing -- are just APPROXIMATIONS based on what seems to work. Our eye's perception of color is much more complex than this. For example, in the 50's, Edwin Land (of Polaroid fame) demonstrated that the eye can generate perceptions of all colors in the color wheel simply from the combination of white and one pure color.

Similarly, there is nothing fundamental or really "scientific" about the choice of the Cyan, Magenta and the Yellow we use for printing, or the frequencies of Red, Green and Blue used on Cathode Ray Tubes. These are simply colors that are easy to produce in those mediums that can be combined with others to approximate colors successfully. Other color systems exist, and have been used to create even better approximations. One of Land's demonstrations is that you can choose almost any two arbitrary colors from the spectrum and generate a perception of colors from across the entire spectrum simply by combining them.