COLOR MIXING The Basic Three

The Physics and Biology of Color Mixing

Color is as much a part of human biology as it is of the physics of light and matter. The study of color and light is a continuing process. Knowledge about how color works and how it affects us is constantly being adjusted and refined.

Two Sets of Primary Colors

The three basic colors for mixing inks, paints, dyes, food coloring and other colorants are not the same three basic colors when it comes to mixing illumination.

PAINT - INKS - DYES				ILLUMINATION
CYAN	YELLOW	MAGENTA		RED	GREEN	BLUE

Yet these two sets of colors are linked together. Mixing any two colors of the one group will give you one of the colors from the second group. Of course colorants or filters will be needed to mix the cyan, yellow and magenta colors. Lamps or light sources would be needed to mix the red, green and blue.

Starting with the same hues, paint and light do not produce the same mixed colors.

PAINTS		ILLUMINATION
(subtractive mixing)		(additive mixing)
Red and green paint mix to make brown, a darker color.		Red and Green light mix to make yellow, a lighter color.

 NEGATIVE - POSITIVE

	BLUE			YELLOW
GREEN
			MAGENTA
	RED			CYAN

When the colors of a picture are reversed, the negative image that results produces opposite or complementary colors. The colors in a color film negative are the opposite of the colors in the final photo paper print. Notice that the flower that appears as red in the negative image is actually a cyan flower in the positive photo. The flower that appears green in the negative turns out to be a magenta flower. The flower that appears blue in the negative is yellow in the photo. So once again we can see a relationship between the red, green and blue of the "additive" primaries and the cyan, yellow and magenta of the "subtractive" color primaries.

(Typical color photographic negative film contains two additional color layers besides the color negative image. These two extra layers form a "mask" to correct for limitations in the color filtering properties of the negative dyes when printed on photographic paper. It is this built-in mask that gives film negatives their characteristic color which may appear an overall orange to brownish pink color.)

WHICH PRIMARIES ARE USED WHEN?

ADDITIVE PRIMARY COLORS ARE USED WHEN . . .

COLOR LIGHT IS MIXED:		red
		green
		blue
When colored light bulbs or spotlights shine on the same area during a stage performance. When our eyes combine tiny colored dots or stripes on a monitor or video screen. When some digital video projectors project discrete red, green and blue images that are superimposed in register on a projection screen.

SUBTRACTED PRIMARY COLORS ARE USED WHEN . . .

COLORS ARE MIXED PHYSICALLY:		cyan
		Magenta
		Yellow
When we mix color paint together. When transparent colored liquids are combined. When we place one colored glass or filter in front of another. When a printer combines several different colored inks on top of each other on paper. When transparent photographic layers are sandwiched together to produce color images. When various colors of modeling clay are kneaded together.

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