Photographic (and analog) processes used in preparing to print images with the printing plates. Color separation is one of the functions of photomechanical processes, making a separate printing plate for each of the color components in a color picture. Usually there are four: one plate for yellow, one for blue (cyan), one for red (magenta), and one for black. Images printed by offset lithography (the printing process by which the majority of periodicals are printed for example) have invariably been photomechanical graphics until computer graphic processes have gotten to take over some of this territory. A computer generated image is more likely to be called a computer graphic or digital graphic.Also see moir?.