The latest development of electronic publishing technology

●Frequency switching technology introduced

Since the advent of the first digitized electronic color separation machine, electronic over-web technology has been a color separation device.

Manufacturers focus on competition. For decades, many scientists have racked their brains, so a variety of technologies and processes came into being. The early competition mainly focused on the AM technology. The main difficulty at that time was how to form an accurate net angle on the film output by the electronic scanning method, and the same number of meshes on the four-color version, which formed a rational grid. Over-web technology, composite grid over-network technology, and irrational grid over-network technology, the vast majority of color prints now seen by people are made by rational grid over-network technology or composite grid over-network technology. It can be said that AM technology did not mature until the early 1990s. In March 1993, AGFA and HELL, the famous electronic prepress equipment manufacturers at the country No.1, announced the birth of FM network technology, which opened a new page of network technology competition.

● Technical advantages of FM over the network

FM uses a fixed-sized ink spot to express the level with its density. In fact, the concept of frequency-tuning over the Internet was born as early as the late 1970s. However, this concept was not developed into available technologies and commodities due to the technical conditions at the time. With the development of electronic computers, the speed of operation has been greatly improved, making it possible to use FM for over-the-network implementation. The Institute of Computer Research of Peking University began researching FM network technology at the beginning of 1991 and gradually mastered several key technologies of FM over the network. In August 1993, it produced the first batch of printed materials, and subsequently launched the Founder 93′ electronic publishing system. It includes FM technology. This technical achievement was applied in Hong Kong Ming Pao Daily and Guangzhou Modern Times in 1994. What is particularly worth mentioning is that newspapers and magazines produced by Ming Pao in Hong Kong using FM technology have achieved very good results. The following is based on the experience of FM technology developed by us over the past few years, and introduces some of its features:

First, in theory, FM over the network will not produce a wrong network. Misconnection is a big enemy that has plagued the color printing industry for decades. The difficulties in the previous AM screening were directly related to the error network. Once there is a faulty net in the printed product, it is a waste product. The faulty net is a product of cyclical structural interactions, and the distribution of FM nets is irregular, and several color overlays do not misplace each other. Even copying textiles in prints or manuscripts will not Misplaced.

Second, FM technology prints are more refined than AM technology prints. No matter how good the AM technology is, it can only avoid the big wrong network. The small wrong net (also known as the rose spot) cannot be avoided. This rose spot is often the direct cause of the rough image. Because the FM net will not produce such rose spots, it is more refined.

Third, the resolution is good. In AM technology, the quality factor determines the sharpness. The larger the quality factor, the smaller the dot area of ​​the output and the better the clarity. However, it is usually difficult to make quality factors too large. Therefore, the output images generated by the amplitude modulation over-the-web technique have to be subtlely emphasized, that is, USM. Since the area of ​​the dot used by the FM network is extremely small, it is equivalent to a considerable quality factor in the AM technology, so the definition is good. Therefore, when the color separation film is produced by using the frequency modulation over-net technology, it can be less emphasized with subtle levels, and even if it is not used, the effect is quite good.

Fourth, FM over the net is not sensitive to overprint errors in the process of printing plate-making, and the traditional amplitude-modulation nets may be misplaced due to overprinting errors.

Fifth, low-resolution imagesetters using FM technology can also obtain high-quality images, while AM ​​technology must require high-resolution imagesetters. For example, the quality of the FM image output from the 1200DPI imagesetter is significantly better than that of the 175-mesh AM image output from the 3000DPI imagesetter.

6. The distribution of the dots in the FM network is irregular, and the distribution of the cerium salt particles in the negatives and photos in the photographic technology is also irregular. In this way, as long as the networks in the FM network are small enough, their printed products can fully approach the original and achieve the effect of high-fidelity.

Seven, can be used for multi-color printing. In the technique of amplitude modulation and netting, the problem of moiré in four-color printing has already made people excited.

For decades, multi-color printing over the net if using AM technology is even more difficult. However, if FM technology is used, the problem can be solved today.

The above describes the advantages of FM over the network technology, it is worth emphasizing that the fourth and fifth points are: In the past, the low-grade photocopying system also had the potential to produce high-grade color printing products, as long as the corresponding equipment was purchased. System upgrade can be. The sixth and seventh technical revolutions will cause a color revolution, that is, 4+ colors.

Printing Technology. However, from the perspective of popularization and application, the popularity of high-quality FM network outlets is more difficult. There are two reasons: First, the high-quality FM network outlets are too small, and there are high requirements for materials and machines in the post-processes such as printing and printing. Second, all the processes must be based on the characteristics of the FM network and data-based methods. New process specifications were developed because the experience of using a magnifying glass to observe the percentage of traditional AM sites was no longer valid.

● Technical parameters of the FM network

In the traditional amplitude modulation over network technology, there are several parameters that are important and that application technicians must understand: the number of meshes, screen angles, and meshes. There is only one parameter for FM over the network, namely the dot size. Taking a 1200DPI photosetter as an example, in theory, one spot is a square with a side length of 1200 inch, but the spot on the actual No is a circle that is slightly larger than the square. . In the case of a certain resolution, we can take a light spot as the ink point, or we can take 2*2 light spots as the ink spots. Of course, 33 laser spots can also be used as the ink spots. From what we have seen from other manufacturers' FM proofs, they use the next light spot of 1200 DPI resolution as the ink point. The proofs look very detailed, almost the same as the photos, and the ink is virtually invisible to the naked eye. point. We experimented with several printing houses in the mainland. As a result, the next light spot at 1016 DPI was not at all good for inked printing, let alone one light spot at a higher resolution. We made

Several batches of proofs are based on 2*2 light spots at 1200DPI. This kind of proof printing has a good effect. That is to say, if a 600DPI photosetter is used, as long as its accuracy is good, it can be made better. For 175-point prints, under normal circumstances, the output text 1016DPI is sufficient. Under the condition of traditional amplitude modulation and over-netting, the resolution of the imagesetter is further increased to output images. Generally, 2400 DPI can have better image effects. The 600DPI in the FM technology has played 175 mesh over the network, so that the image contrast resolution

But lower than the textual requirements, this is the charm of FM over the net. We have previously sold low-resolution imagesetters, mainly 742DPI, 1016DPI, 1200DPI (approximately 1270DPI), and 1524DPI. in case

After the process to keep up, phototyped body and good repeatability of positioning, then the quality of these imagesetter output FM network should be the following order: 1200DPI 1*1 is the best, then 1016DPI 1*1, 2*2 under 1524DPI (approximate 1*1 under 742DPI), 2*2 under 1200DPI, and 2*2 under 1016DPI (with

Under 1524DPI 3*3). We believe that the smaller point under the existing conditions than the next light spot of 1200DPI is not printed. The larger point than 2*2 under 1016DPI is too coarse to be used. How much light will be used for ink

The point is closely related to the printing level of this unit.

●Conclusion

We believe that with the continuous development of the printing industry, as people's requirements for color prints continue to increase, FM over the network technology will continue to be promoted. We hope to invite the printing industry together with us to work together to popularize FM technology.