Color Space & Gamut

Gamut — CMYK vs. RGB

Gamut refers to the range of colors that any device is capable of reproducing or recording. There are two basic color spaces, RGB (additive color) and CMYK (subtractive color). Additive color systems start without light (black). Light sources of various wavelengths combine to make a color (red, green, blue). Examples of RGB systems would include human vision, digital scanners, digital cameras and monitors.

The subtractive color model explains the mixing of paints, dyes, inks and natural colorants to create a full range of colors by subtracting (that is, absorbing) some wavelengths of light and reflecting others. This is the process used for all printed media such as inkjet prints, magazines and books, etc. Known as CMYK, it's based on the cyan, magenta, yellow and black colors used in the modern-day print process. It can also include spot colors, metallic and other specialty inks.

Left is a CIE representation of the relative color gamuts of Adobe RGB (green), sRGB (red) and SWOP CMYK (blue). Right is SWOP (standard web offset press), the innermost outline and various inkjet printer gamuts, showing larger than SWOP color printing capabilities.