A color model is simply an agreed-upon way of describing color.
Because color is so subjective and so important in our perception of the world, there have been, over time, many different models created to explain, define, and specify color. Sometimes the promotion of various models has taken on the flavor of an operating system war! ("My color model is better than yours!")/p>
In day to day practice, you'll most likely use two models: HSV and RGB. You'll also hear a lot about CMYK.
HSV stands for Hue, Saturation, and Value, and it uses these three concepts to describe a color. You'll encounter it most often in your illustration and image editing programs. RGB stands for Red, Green, and Blue, and uses these three concepts to define a color. You'll use this in specifying colors within CSS or HTML code. Your image editing programs might also provide tools for picking color this way. Most programs provide you ways to translate the values of one model into the values of another. For exmaple, you can usually find the hex value of a color you've selected from an HSV color wheel -- the hex value is an RBG representation of that color.
CMYK is the color model used for printing. If you are using your illustration and image editing programs to prepare material for printing, you may want to work within the CMYK space from the very beginning. Pantone, another term you might hear, is an extensive and widely-used set of color inks and many programs let you pick specific Pantone colors as well. As with CMYK, this is important only if you are taking your work to a printing press or trying to match a printed color on a Web site.
Taken together, hue, saturation, and value combine to form the HSV color model.
HSV is the color selection model used most often in illustration and image programs, like Fireworks and Freehand. Color selection based on these criteria is often presented as a color wheel, with hues along the outer edge at full saturation, and with saturation decreasing as you move to the center of the circle. Value or intensity is adjusted with a brightness bar. Hue is presented as an angle point, while saturation and value are meaureed as a percentage between 0 and 100:
|To create HSV colors on the computer you select a hue and saturation on the color wheel. Hues are around the edge of the wheel, saturation increases with the distance from the center. Value is selected from a dark to light slider.
RGB stands for red, green, bluethe three colors that make up an image on a monitor.
The RGB color model is an additive model used for displaying images on a computer monitor or other screen device. When the three primary colors, red, green, and blue, are combined they make a white light. When all are absent, there is black. Projected colors often feel much brighter than their subtractive model counterparts.
To create RGB colors on the computer you must specify percentages of each of the primary colors. Color is controlled by moving the sliders:
This purple color is a mix of 56% red, 5% green, 61% blue: