The CUPS filtering system is distributed into three different layers:
If we look at UNIX and Linux printing systems, individual applications are responsible for creating the printing output rather than the X window system or the OS kernel, which are independent of any application's behavior. Most applications use PostScript, but PostScript offers many ways to handle print output. We will discuss those methods here:
Converter: Pages cannot be directly printed in formats such as PDF, GIF, and so on. Hence they generally require a conversion to PostScript, which is the only format CUPS can understand.
Filter: Once the pages are converted into the PostScript file format, it will then be sent to the printer filter. This filter is nothing but a built-in interpreter called a "Raster Image Processor" (RIP). The RIP converts PostScript file into high-resolution raster images for printing as we can see here in the following figure. It shows a printing mechanism...
