乘同余法伪随机分布调频加网方法研究

研究了在彩色桌面出版系统中，借助现有的调幅加网ＲＩＰ，采用乘同余伪随机数序列分布点元素，实现调频加网的基本原理和技术。选用乘同余法产生伪随机数序列，探求出适合调频加网要求的乘同余随机函数的Ｘ０、Ａ、Ｍ三个参数的正确选择方法。研究表明，采用伪随机函数，对分色后的图象文件进行调频加网，再经现有的调幅加网ＲＩＰ，可实现图象的调频加网输出；通过选用不同的随机数序列起点，或选用不同的随机数序列，可保证图象中大片灰度值相同的区域不出现纹理现象。

A Study of Pseudo-Random Distribution FM Screening with Multiplicative Congruence Arithmetic

This paper mainly deals with the basic theory and technique of FM screening with the help of AM screening RIP and the application of pseudo random series of multiplicative congruence arithmetic in color DTP. The multiplication congruence qrithmetic is selected to produce the pseudo random series and probe into the correct methods for selecting three parameters X 0, A, M, suitable for the multiplicative congruence random function. Research results show that by using the pseudo random function and RIP for AM screening, the image of separate color can be input in the form of FM screening. At the same time, by selecting different beginning points of random series or different random series, it can be ensured that there is no grains in the large area of image with the equal gray values.