Color Newspaper Printing Quality: Application of New and Old Network Technology (2)

So why is the expansion of the FM network outlets larger? Let's do the following analysis.

Suppose: δ = the expansion value of the dots at the time of printing, and R = the radius of the dots, as shown in Fig. 5, then: the dot expansion area ≈δx2πR, the dot expansion per unit area ≈ 2 π R/ n RR = 2 /R.

Visible network expansion is inversely proportional to the radius of the network, and the FM network is much smaller than the amplitude of the network. Therefore, the network of the FM network will have serious network expansion from dark tone to high tone.

The larger the dot expansion value per unit area, the more sensitive to changes in the printing pressure, the amount of ink, the printing speed, etc., thus making it difficult to control the level and color of the color newspaper. In addition, due to the different characteristics of each press, resulting in different network expansion values, each printer usually requires a set of calibration data, so that each set of FM screen printing plate can only fit a specific printing press, and increased production. The difficulty.
Poor printing process is the fatal weakness of FM network, high quality is accompanied by high cost. Therefore, although the FM network has been popularized for many years, it has rarely been actually used, even in regions where CTP is widely used.

FM/AM sites are based on the above reasons, and hybrid networks that combine the advantages of AM and FM networks have emerged. This network technology has also undergone several generations of changes.

The first generation: the details of frequency-added screening and screening, and the amplitude-added screening performance of the flat screen are the obvious flaws in the transition between the FM and AM networks, and the network computing time is very long.

The second generation: FM radio network expression highlights, AM screening performance midtones, its flaw is that there are still traces between the FM and AM network, network computing time is still very long.

Third, breakthroughs in the printing quality of new outlets and newspapers
Based on hybrid networks, a brand new XM (Cross Modulated Screen) network came into being. It fully absorbed the advantages of FM and AM, perfectly solved the transition problem between the two, and can easily use existing printing equipment. And the technology printed high-line newspapers on newsprint web pages and newsprint papers, up to 180 lpi, enabling the newspaper's image quality to achieve the effect of the magazine, and truly achieved a breakthrough in newspaper printing quality.

1. The basic principle of XM outlets
XM outlets use AM sites to express midtones (8-92%), FM sites express bright (0-8%) and dark (92-100%), and the conversion points of the two vary with the number of network lines (see The following figure).

(to be continued)