ABOUT PROCESS COLOR
A process color is printed using a combination of four standard process inks: cyan, magenta, yellow, and black (CMYK). Use process colors when a job requires so many colors that using individual spot inks would be expensive or impractical, as when printing color photographs.
Keep the following guidelines in mind when specifying a process color: For best results in a printed document, specify process colors using CMYK values printed in process color reference charts, such as those available from a commercial printer. The final color values of a process color are its values in CMYK, so if you specify a process color using RGB or LAB, those color values will be converted to CMYK when you print color separations.
These conversions work differently when you turn on color management; they are affected by the profiles you specify. Donâ€t specify a process color based on how it looks on your monitor, unless you are sure you have set up a color management system properly, and you understand its limitations for previewing color. Avoid using process colors in documents intended for online viewing only, because CMYK has a smaller color gamut than that of a typical monitor.