Color theory defining the CMY primaries as substances that "absorbed" only one of the retinal primary colors: cyan absorbs only red (−R+G+B), magenta only green (+R−G+B), and yellow only blue violet (+R+G−B). It is important to add that the CMYK, or process, color printing is meant as an economical way of producing a wide range of colors for printing, but is deficient in reproducing certain colors, notably orange and slightly deficient in reproducing purples. A wider range of color can be obtained with the addition of other colors to the printing process, such as in Pantone's Hexachrome printing ink system (six colors),
Color management channels are RGB (mainly for display (monitors) but also for some desktop printing) and CMYK (for commercial printing). An additional "alpha" channel may specify a transparency mask value. Some image software (such as Photoshop) perform automatic color separation to maintain color information in CMYK mode using a specified ICC profile such as US Web Coated (SWOP) v2. , most web browsers ignored color profiles. Notable exceptions were Safari, starting with version 2.0, and Firefox starting with version 3. Although disabled by default in Firefox 3.0, ICC v2 and ICC v4 color management could be enable by using an add-on or