The Color Dance
No device in a publishing system is capable of reproducing the full range of colors viewable to the human eye. Each device operates within a specific color space that can produce a certain range, or gamut, of colors.
A color model determines the relationships between values, and the color space defines the absolute meaning of those values as colors. Some color models (such as CIE L*a*b) have a fixed color space because they relate directly to the way humans perceive color. These models are described as being device-independent. Other color models (RGB, HSL, HSB, CMYK, and so forth) can have many different color spaces. Because these models vary with each associated color space or device, they are described as being device-dependent.
Because of these varying color spaces, colors can shift in appearance as you transfer documents between different devices. Color variations can also result from differences in image sources; the way software applications define color; print media (newsprint paper reproduces a smaller gamut than magazine-quality paper); and other natural variations, such as manufacturing differences in monitors or monitor age.
What is a color management system?
Color-matching problems result from various devices and software using different color spaces. One solution is to have a system that interprets and translates color accurately between devices. A color management system (CMS) compares the color space in which a color was created to the color space in which the same color will be output, and makes the necessary adjustments to represent the color as consistently as possible among different devices.
A color management system translates colors with the help of color profiles. A profile is a mathematical description of a device’s color space. For example, a scanner profile tells a color management system how your scanner “sees” colors. Adobe color management uses ICC profiles, a format defined by the International Color Consortium (ICC) as a cross-platform standard.
Because no single color-translation method is ideal for all types of graphics, a color management system provides a choice of rendering intents, or translation methods, so that you can apply a method appropriate to a particular graphics element. For example, a color translation method that preserves correct relationships among colors in a wildlife photograph may alter the colors in a logo containing flat tints of color.
Note: Don’t confuse color management with color correction. A color management system won’t correct an image that was saved with tonal or color balance problems. It provides an environment where you can evaluate images reliably in the context of your final output.