Industry users details: pre-press proofing differences

With the development of science and technology, pre-press proofing technology has also increased. Now based on the traditional offset printing proofing, Ke Linglin proofing analog offset printing, digital proofing use summary, a simple comparative analysis of the three.

In this paper, these three proofing methods are used as the center of the explanation in terms of quality (reducibility, stability), efficiency, cost, printability, operability, and environmental protection.

Offset proofing - market mainstream
There are many variable factors in offset proofing, such as ambient temperature and humidity, proof pressure, ink quality, on-site density, dot gain, exposure and development control, ink balance, human factors, etc., so offset control has a lot of quality control points. The comprehensive skill requirements of the samplers are relatively high, and the stability of the proofs is also poor.

Due to the nature of offset printing proofing, the consumables for proofing - PS plate, ink, paper, developer, fixer, car wash, fountain solution, gasoline, etc., are determined, and the overall cost is higher. However, the cost of multiple sheets is relatively low. For example, the cost of printing a sheet offset printing is 80 yuan, but the cost of multiple sheets of proof is basically 80 yuan + the price of N sheets of paper. When the number of customer samples is large, the cost is high. Lower.

Based on the characteristics of offset printing proofing, from the completion of prepress production to obtaining finished product proofs, the middle part needs to be printed, imposition, printing, developing, proofing, and washing ink. The time is longer, usually 1.5 to 3 hours. This is usually Depending on the offset printing machine color group, proofing operator comprehensive skills. The vast majority of off-the-shelf offset printing and proofing equipment is round-press flat. The proofing speed is much lower than the printing speed, but its adaptability is close to that of offset printing. Can be used for offset printing proofing more substrates, coated paper, offset paper, gold cardboard, silver cardboard, the current traditional offset printing proofing still prepress prepress (mainly in the offset printing industry) market mainstream.

Cromarin proofing - good quality and high cost
Cromartin proofing is not widely used in China, and a brief introduction is made to its proofing principle.

The viscous photographic film is transferred to the substrate, so that the substrate has a photosensitivity, and then on its positive photo film, the UV exposure, the photopolymer film light cross-linking occurs, curing, lose the original viscous Sex, no light part to maintain its viscosity, color foil or toner is sticking to color.

There are few variable factors in Cromax's proofing, mainly adjustable exposure time, photosensitive film thickness (the thickness of the film is currently used in two sizes), and the main adjustable parameter affecting the proof is the exposure time.

According to the proofing imaging principle and the author's experimental data analysis, the expanded value of Cromarind's proofing is the expansion of light refraction, and unlike the actual expansion of offset proofing, the numerical value is stable.

The principle characteristics of Cromarin's proofing determines that the proofing time is relatively short, such as four-color, A2 format, skilled operators can be completed in 15 to 25 minutes.

Repeated proofing is more stable, whether one person plays the same Zhang multiple times, or whether different people play the same Zhang, as long as the exposure parameters are unified, the color difference between the proofs is very small, and the visual basic is not felt (overprint accuracy is affected to some extent Chromatic aberration requires that the operator must be careful and careful when sticking the film to minimize the error.

Cromarin's proofing is to cover the photosensitive film every time it hits, exposing the light once, covering the color foil or toner, so its cost is proportional to the number of proofs. In the current market situation, the cost is higher than traditional offset printing. But its short proofing time, high efficiency, proofing controllability, easy to operate (normal workers can learn to operate within an hour, and proofs played more than many years of work experience is not inferior), at the same time, it meets environmental protection requirements, And a wide range of substrates, some manufacturers in the country. To a certain extent, it is a substitute for traditional offset printing and proofing. The quality is relatively good but the cost is one of the factors that restricts its development.

Digital proofing - obvious advantages, need to be improved
After the development of digital proofing in recent years, whether it is a software environment or hardware facilities, its technology is basically mature, according to its principles can be roughly divided into laser type, inkjet type, thermal sublimation and other types. The high-resolution color inkjet printers have a dominant position in pre-press proofing because of their high performance-to-price ratio. A discussion of color inkjet printer proofing features is given.

The stability of digital proofing is very high. Different people print the same file at different time periods. As long as the ICC parameter settings are the same, the color difference of proofs cannot be felt within the visual range.

The advantage of digital proofing is that it can simulate several printing features to some extent. As we all know, each printing method has its own characteristics. Different printing manufacturers of the same printing method, regardless of whether they are large or small, have more or less unique technical characteristics. Digital proofing can be used in digital proofing. Simulate different printing effects on the machine.

The digital proofing speed is very fast. The time required for a normal A3 size document to be printed from the time of generating a document to printing is about 10 minutes. This is related to the network speed and computer configuration.

With the support of EPSON and Beijing Huali Zhicheng, the author tried a week before the EPSON PRO 7600 was released in China. Compared with traditional offset proofing or prints, Cromartin, EPSON 5000, and EPSON 7000, the proofs are more detailed and rich in the tone levels, and are not lost in the high-profile areas. They are very good for dark tone level reproduction. This is of course related to the maturity of the color management software used.

Digital proofing environmental pollution is another advantage. From the current market situation analysis, the cost of digital proofing is lower than traditional offset proofing. The adjustability depends on the configured color RIP management software. The quality depends on the hardware parameters of the printer, such as resolution, drop size, etc. The color management software Best Color, Color tune, etc. have a good performance.

Comparing and analyzing the above three prepress proofing systems, digital proofing has a very good performance in terms of quality (reducibility, stability), efficiency, cost, and environmental protection, and the era of prepress proofing, which is mainly based on digital proofing, is already in progress. Take a big step toward us.

Digital proofing needs improvement
1. The digital proofs are exquisite and rich in levels, especially for high-profile areas, dark areas, and subtle areas. In the actual printing (both offset printing and gravure printing), there is a certain overprinting error, and because of the characteristics of the amplitude modulation dot network itself, the level reproduction of this part of the area is not as good as digital proofing to some extent. However, some of the direct customers may not receive the product because they do not understand it. "This has brought a big problem to the platemaking and printing industries. It takes time to explain.

Therefore, it is recommended that RIP production companies add an “overprint accuracy” or “register accuracy” in future versions, and offset the entire color within a certain accuracy range, so that different values ​​can be entered for different overprinting accuracy printing equipment. In order to achieve the consistency of printing products and proofing, this technology has a certain market at this stage.

2. Spot color proofing. Although many current RIPs that control digital proofing support spot colors, they can also simulate very realistic spot colors (small color differences are almost indistinguishable). However, spot colors for digital proofing are ultimately simulated with basic colors, which are different from actual colors. Spot color in printing.

It is suggested that RIP production company will add another one in the future version, "spot power" or "transparency" of spot colors. Because in the prepress production, in order to improve the printability, it is often necessary to do trapping (pressure blanking), overprinting (direct pressure) and other effects. Taking gold ink and silver ink as examples, such printing inks have strong hiding power. However, digital proofing does not show its proper effect when printing gold or silver, and often the situation of discoloration occurs. If this problem is solved, the digital proofing system will be even more powerful and its development will become increasingly perfect!



Source: Digital Printing Song Desheng

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