Research On Raster Image Processor Based On Pre-Function Library Screening Algorithm

Raster image processor (RIP) is the core of the prepress processing system. The main function of it is to change image, graphics and text to the binary lattice information, which can be handled by output device. It will also control the output device to record the lattice information in various media. The output speed, quality and openness of a desktop system depend on the quality of raster image processor to a large extent. While the explaining speed and screening quality are two key points of the main technical indicators to measure the performance of the raster image processor. It can be through improving the speed of digital screening and perfect the digital screening algorithm to improve the explaining speed and screening quality of the raster image processor. Based on the patent of "method to realize direct printing through the correlation logic intelligence screening", this topic designs and realizes a new digital screening method-Pre-function library screening algorithm.This paper introduces the basic of raster image processor, explains the significance of digital screening method in improving the performance of raster image processor, and then introduces the PostScript language and PDF files. It focus on the analysis of traditional amplitude screening and frequency modulation screening, such as pattern dithering algorithm and error diffusion algorithm, as well as pre-image library screening algorithm. Then it makes programming simulations for various algorithms, and illustrates the advantages and disadvantages of all kinds of algorithm according to the simulation results. On this basis, it puts forward the pre-function library screening method, and detailed illustrates the basic principle and algorithm process of this screening method, as well as realizes it by programming. Finally designing a contrast experiment, that is to dispose a same size Lena standard drawing by using a variety of different screening algorithms. The experimental results show that the performance of pre-function library screening method is the most balanced in the evaluation of simulation results and algorithm execution time.