Raster image processor
http://en.wikipedia.org/wiki/Raster_image_processorWHAT IS A RIP?
In its simplest form, a RIP (Raster Image Processor) interprets the data from your image file into a form that your printer can understand. This translated information tells your printer how to lay down dots of ink to reproduce your image on the printed page. Most RIPs available today can process raster data (bitmap or photo), vector data (design elements created in a graphics application), and text.
WHY DO I NEED A RIP?
Most large and wide format printer manufacturers provide some sort of printer driver or rudimentary onboard RIP to interpret the information in your files. However, most users need more than this in order to achieve optimal results from their printer. A professional RIP optimizes the performance of virtually every large or wide format device available today, in terms of color reproduction, throughput speeds, and workflow efficiency, in ways that lesser RIPs simply cannot.