Reproducing colors
Colors on a monitor are displayed using combinations of red, green, and blue light (called RGB), while printed colors are typically created using a combination of four ink colorscyan, magenta, yellow, and black (called CMYK). These four inks are called process colors because they are the standard inks used in the four-color printing process.     RGBimage with red, green, and blue channels      CMYK image with cyan, magenta, yellow, and black channelsBecause the RGB and CMYK color models use different methods to display colors, they each reproduce a different gamut, or range of colors. For example, because RGB uses light to produce color, its gamut includes neon colors, such as those you'd see in a neon sign. In contrast, printing inks excel at reproducing certain colors that can lie outside the RGB gamut, such as some pastels and pure black.A. Natural color gamutB. RGBcolor gamutC. CMYK color gamut RGBcolor model CMYK color model But not all RGB and CMYK gamuts are alike. Each model of monitor and printer is different, and so each displays a slightly different gamut. For example, one brand of monitor may produce slightly brighter blues than another. The color space for a device is defined by the gamut it can reproduce.
RGB model
A large percentage of the visible spectrum can be represented by mixing red, green, and blue (RGB) colored light in various proportions and intensities. Where the colors overlap, they create cyan, magenta, yellow, and white.Because the RGB colors combine to create white, they are also called additive colors. Adding all colors together creates whitethat is, all light is transmitted back to the eye. Additive colors are used for lighting, video, and monitors. Your monitor, for example, creates color by emitting light through red, green, and blue phosphors. |
CMYK model
The CMYK model is based on the light-absorbing quality of ink printed on paper. As white light strikes translucent inks, part of the spectrum is absorbed while other parts are reflected back to your eyes.In theory, pure cyan (C), magenta (M), and yellow (Y) pigments should combine to absorb all color and produce black. For this reason, these colors are called subtractive colors. Because all printing inks contain some impurities, these three inks actually produce a muddy brown and must be combined with black (K) ink to produce a true black. (K is used instead of B to avoid confusion with blue.) Combining these inks to reproduce color is called four-color process printing. |
An ICC profile is a description of a device's color space, such as the CMYK color space of a particular printer. In this lesson, you'll choose which RGB and CMYK ICC profiles to use. Once you specify the profiles, Photoshop can embed them into your image files. Photoshop (and any other application that can use ICC profiles) can then interpret the ICC profile in the image file to automatically manage color for that image. For information on embedding ICC profiles, see Photoshop Help. |
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