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Color models and color spacesA color model is a way of describing color using numbers so that computers can operate on them. The color model used within After Effects is the RGB color model, in which each color is described in terms of amounts of red, green, and blue light added together to make the color. Other color models include CMYK, HSB, YUV, and XYZ. A color space is a variant of a color model. A color space is distinguished by a gamut (range of colors), a set of primary colors (primaries), a white point, and a tone response. For example, within the RGB color model are several color spaces, including—in decreasing order of gamut size—ProPhoto RGB, Adobe RGB, sRGB IEC61966-2.1, and Apple RGB. Although each of these color spaces defines color using the same three axes (R, G, and B), their gamuts and tone response curves are different. Though many devices use red, green, and blue components to record or express color, the components have different characteristics—for example, blue for one camera is not exactly the same as blue for another camera. Each device that records or expresses color has its own color space. When an image moves from one device to another, image colors may look different because each device interprets the RGB values in its own color space. Color management uses color profiles to convert colors from one color space to another, so colors look the same from one device to another. Online resources about color models and color spacesAdobe provides a white paper on color spaces and color management in After Effects, on the Adobe website. Charles Poynton provides an excellent set of resources on his website regarding color spaces, color management, and other color technology. Christopher Nevison provides an article on the Colgate University website that explains and describes the uses of the RGB, CMYK, HSL, HSB, and YCbCr color models. Harry Frank provides a video tutorial on his graymachine website that shows how and why to use color conversion expressions to convert colors from the RGB color model to the HSL color model when randomly varying colors. The specific example that he shows uses the Radio Waves effect. |