Raster image processor

A Raster image processor is a part in some printers. The raster image processor receives the data in a description language, like Postscript, PCL, or PDF and changes it to a bitmap or raster image. 
Raster image processing can be done in two ways: as Software running as part of the operating system, or as a special microprocessor inside the printer. Cheaper printers use a solution called host-based printing, where this is done in the operating system, more expensive printers, and those that support PCL, Postscript or a similar language have a Raster image processor inside the printer.