Understanding colour on your computer

Understanding color models

You need a precise method to define colours. Colour models provide various methods to define colours, each model defining colours through the use of specific color components. There are a range of color models to choose from when creating graphics.

CMYK color model

The CMYK color model defines color using the following components:

	C Cyan
	M Magenta
	Y Yellow
	K Black

The cyan, magenta, yellow, and black components are the amounts of cyan, magenta, yellow, and black ink that a CMYK color contains and are measured in percent from 0 to 100.

The CMYK color model is a subtractive color model. Subtractive color models use reflected light to display color. Printed materials are produced using the CMYK color model. When you combine cyan, magenta, yellow, and black, so that the value of each component is 100, the result is black. When the value of each component is 0, the result is pure white.

RGB color model

The RGB color model defines color using the following components:

	R Red
	G Green
	B Blue

The red, green, and blue components are the amounts of red, green, and blue light that an RGB color contains and are measured in values ranging from 0 to 255.

The RGB color model is an additive color model. Additive color models use transmitted light to display color. Monitors use the RGB color model. When you add red light, blue light, and green light together, so that the value of each component is 255, the color white displays. When the value of each component is 0, the result is pure black.

HSB color model

The HSB color model defines color using the following components:

	H Hue
	S Saturation
	B Brightness

Hue describes the pigment of a color and is measured in degrees from 0 to 359 (for example, 0 degrees is red, 60 degrees yellow, 120 degrees green, 180 degrees cyan, 240 degrees blue, and 300 degrees magenta). Saturation describes the vividness or dullness of a color and is measured in percent from 0 to 100 (the higher the percentage, the more vivid the color). Brightness describes the amount of white that the color contains and is measured in percent from 0 to 100 (the higher the percentage, the brighter the color).

Grayscale color model

The Grayscale color model defines color using only one component, lightness, and is measured in values ranging from 0 to 255. Each Grayscale color has equal values of the red, green, and blue components of the RGB color model.