In computer graphics and imaging, the hardware and software configuration used in output devices to determine what value each pixel or spot of output should possess, driven by commands from a page description language such asPostScript. All computer-generated output (such as that produced on an imagesetter) is composed of very small spots. The RIP converts a vector-based image, or an image—such as type or line art—stored by the computer as a series of mathematical formulas that describe lines and curves, into the pattern of spots needed to generate the output. (The conversion of a vector image to a raster image is called ripping or RIPing.) Essentially, an interpreter in the hardware converts a PostScript file into a display list, which is then converted into a bit map describing the page. Most PostScript output devices have a RIP built into the hardware.
The earliest RIPs had difficulty with halftone screening, but PostScript screening (via PostScript Level 2) is now of very high quality. Another problem service bureaus have had with PostScript-driven RIPs is the occasional PostScript error and the lack of editability of the PostScript file, which often necessitated going back to the original application file and modifying it. Newer PostScript interpreters allow the editing of the display list before ripping, enabling operators to clean up problematic PostScript files.