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Additive Primary Colors

SmartNote: 8
Type: Term
ColorGeek factor: unrated
Red, Green and Blue are additive primary colors. That is, in an imaging system which creates colors by using light (monitors, file recorders), red green and blue can combine in equal quantities to produce white. All the colors the device is able to create (the device?s gamut) are produced by varying the amounts of red, green and blue.

See Also

Term: RGB
Term: Subtractive primaries

Indexed Color

SmartNote: 81
Type: Term
ColorGeek factor: unrated
When a computer?s graphics system uses 8 bits of information to store each pixel in an image, the most effective way of gaining the widest range of colors is to use a Color Look Up Table (CLUT). This is called indexed color. Each pixel can be one of 256 colors (2^8) and the colors are chosen from a palette of 16 million. If the palette is chosen carefully and the image doesn?t have too wide a range of color, you can get a reasonably pleasing result. The choice of pallete, and what your operating system does to it, however can really mess up your images. Both the Mac OS and Windows have standard 256-color palettes (not that same colors of course). They are called the system palettes and were chosen to have the widest application possible. Photoshop can create custom palettes for your images but beware that the system displaying your image may not have access to the custom palette.

Ink

SmartNote: 83
Type: Term
ColorGeek factor: unrated
absorption - see dot gain

Spot Color inks are opaque and Process Color inks are transparent.
What does this mean? Well, when you use Spot colors (like Pantone colors) the ink that is applied to the page on the press does not let light through to the paper and so is affected a lot less by the color of the paper. But, when using 3 or 4-color process inks, the ink is transparent (so each ink color is able to modify the light) so the light hitting the page passes through the ink, gets reflected off the page, and then passes through the ink again before it travels to your eyes. This means that the color of the paper stock plays a huge role in determining the final look of your output.

It also means that spot colors emulated on a 4-color proofing device are affected by the proofing stock much more than they will be on the final press output. Nasty!
What do I do about it? A well-made printer profile should take paper stock color into consideration but you should note that the Rendering Intent you select will or will not correct for the stock color? choose this carefully.

See Also

Term: Dot Gain
Term: Rendering Intent

L

SmartNote: 88
Type: Term
ColorGeek factor: unrated
The L component in Lab and HSL color spaces is the lightness of the color.

See Also

Term: CIELab, Lab
Term: HSL - Hue Saturation and Lightness