Difference between FM network technology and AM network technology

The emergence of Frequency Modulated Halftone Dots (FM stands) and its advantages in the resolution, non-profiling, and graphic and textual integration have received widespread attention from the printing industry. With the improvement of materials and supporting technologies, it will become a major screening method that is superior to traditional amplitude modulated dots (AM). The conventional screening technology uses the method of changing the dot size to reproduce the color and gradation changes of the continuous tone manuscript. Compared with the meaning in the radio technology, the size of the changing dot corresponds to the amplitude modulation in the radio technology. For this reason, the FM screening technology is used. After the advent of people, the sites created by conventional screening technologies are called AM sites.

The difference between the FM network technology and the AM network technology lies in that it does not change the size of the network, but the computer generates the same size of the pixels in the digital image. The minimum diameter of these points can be equal to the recording accuracy of the equipment. . A set of finite point groups in a halftoning unit constitutes a very special form of dots, but it does not have a fixed shape because the positions of these dots appear to be random and are sometimes referred to as "random dots", for example two Pixels that are exactly equal in value use FM screening to form dots. Although the number of recorded dots is the same, they appear in different positions. The sum of the areas that make up an FM recording point is equal to the size of a regular dot, and its area ratio is also equal to that of a regular dot. AM sites are the effect of the tonality of the image by the size of the site. The frequencies of the sites in the space and the number of Internet sites per unit area are constant, and the tonality of the image is expressed by changing the area of ​​the site. That is, the site of the bright tone is small and the tone is dark. The network is large; the area of ​​the FM network is fixed, and the tone of the image is expressed by changing the distribution density (density) of the network in the space.


"Guangdong Printing" 2004 No. 4 Liu Qihong