Data management method I for copying and restoring

The purpose of color printing reproduction is to use dots to restore the color of the original, that is, the printed copy should be visually consistent with the original. It is self-evident that the color depth of the original (such as photos) is expressed by the density, while the color depth of the printed copy is expressed by the dot percentage of the ink. Therefore, it is impossible for the printed copy to be completely consistent with the original. The goal pursued by the printer is to make the printed copy as close to the original as possible

in recent years, China has imported a large number of advanced printing and reproduction equipment (such as color desktop plate making system and Heidelberg four-color offset press), but the printed copies are quite different from the originals, and the quality of printed products is also quite different from that of advanced countries. The main reason is that staff often act based on experience and do not organize production according to scientific methods. It is difficult to achieve the expected purpose to manipulate advanced printing and reproduction equipment based on experience. After nearly two years of efforts, Beijing Shangpin plate making company has put forward the views of "developing color printing and reproduction as a high-tech industry", "experience without theoretical basis is not good experience", "every step of color printing and reproduction should be strictly implemented with data management", and has achieved gratifying results. Now, the experience summarized by Shangpin company in the past two years and some technical improvements made in color printing and reproduction are introduced as follows, hoping to play a role in attracting jade

color printing reproduction is divided into two parts: color printing plate making and color printing. Color printing plate making mainly adopts color desktop plate making system, which is generally divided into four parts: scanning, production, film production and proofing. Every part should have a set of scientific detection methods. Empirical things without theoretical basis are unreliable. Because each unit uses different equipment, raw materials and testing tools, the data will also be different. Only by determining the data of each unit according to the theory and scientific testing methods can the purpose of restoring the original be ensured. Taking Shangpin company as an example, this paper introduces how to determine the various detection values of each step

Shangpin company has a crosfield 646 electric extension, through the high-end connection of Sun workstation, a panther46/hs four open Phototypesetter, 9 Apple computers, a Japanese kf-123 proofing machine, and other auxiliary equipment such as film developer and fixer, laser printer, PS version developer, plate printer, and transmission and reflection densitometer. The raw materials used include Kodak film, PS version, DIC ink, imported 157G coated paper, electric extension cleaner, blanket recovery cleaner, ink cleaner, film detection signal strip, proofing detection signal strip, standard color block, etc. invented and produced by our company

clausfield electric extension is mainly used for scanning. First, make it in the best working state, establish the gray balance parameter value of 16 standards and the amount of 24 standard color correction channels, and ensure that the gray and color in the original are faithfully restored. Second, implement the standardized calibration method, use the whitest and blackest steps of the gray ladder as the calibration points of the white field and the black field, set the white field to 0% with the auto key, and set the black field to 93% with the C version, so as to restore the gradation of the original. Third, in order to test the scanning effect and the accuracy of the data transmission of the joint interface system, take two Kodak gray scales (one is a reflection gray scale, the other is a transmission gray scale) and a group of Kodak standard color blocks, scan the gray scale and standard color blocks as standard originals, transfer the scanning results into Apple computer, and open the scanned two scales and standard color block maps with Photoshop software, Use the straw tool to record the detection value (CMYK) of each ladder or each color block. Since the scanning head of the electric extension is a densimeter, use the scanning head to align each step or each color block of the two ladders to detect the C, m, y, K values of each step and color block, record these data and compare them with the corresponding data detected by Photoshop software. If the data are basically consistent, It means that there is no information loss in the process of transferring the parameters set by the electric extension scanning to the apple computer

scanning is the key to restoring the original

scanning is the key to restoring the original. Many plate making centers use platform scanners to scan and then produce films for proofing. As a result, the level and clarity of the pictures are relatively poor, which makes it difficult for customers to accept. If you want to make high-end printed copies, you must first think of using the high-end combined scanning of the electric extension, or scanning with the roller scanner, especially with a scientific calibration method, otherwise it is difficult to restore the original

to detect the scanning quality, we must have gray scale, standard color block, scanning head of electric extension and straw tool of Photoshop. The purpose is to detect whether the electric extension truly displays the data of the original in the computer image file, and also to detect whether the calibration method is correct in the scanning process, so as to provide a simple calibration method to restore the original

pay attention when making with Apple Computer

pay attention when making with Apple Computer: the pictures scanned by the electric extension can only be cleaned and cut. Try not to adjust the level, clarity, contrast, etc. of the pictures, and do not enlarge or shrink them. Try to solve these problems when scanning with the electric extension. The picture format must be CMYK format. If the manuscript has major defects, it can be adjusted appropriately with the permission of the customer. This is a task that the traditional electronic division mechanism version cannot complete. In other words, Shangpin mainly uses Photoshop, freehand, quark, PageMaker and other software, and mainly uses Hanyi font library and founder font library. Computer production can integrate text and pictures, and make an inkjet sample for customers to proofread. Before releasing the film, a laser sample must be made for customers to compare. The tools for testing the production quality mainly include color inkjet printers, screen correction, laser printers, and standard color blocks made by the fixed ink paper used by the company according to the standard density. The purpose is to prevent unnecessary errors in explaining the basic characteristics of the hydraulic universal testing machine when publishing, so as to avoid wasting film

film production is the process most prone to problems

film production is the process most prone to problems, but everything changes. As long as the percentage of points in the image is faithfully displayed on the film. To this end, our company has designed a set of signal bars to detect the quality of the film, as follows:

the color of each color block is filled in c:x% m:x% y:x% k:x% according to the data under the block (X represents the data under the block). Make a PageMaker file, send, develop and fix the PageMaker file according to the routine, and use the transmission densitometer to detect the point percentage data of each square. If the difference between the upper and lower part of the set data is not more than 2, it indicates that the adjustment of the imagesetter and the developer is very consistent, otherwise the redness data of the imagesetter will be readjusted. Shangpin company stipulates that every time a roll of film is changed and the developer is cleaned, the signal strip must be used to detect it once, and the official film distribution can be carried out only after it meets the standard requirements. Fortunately, each version of the software has a signal strip after sending the film. If you are not sure, you can also spot check the signal strip data around the film

the quality of the film directly affects the effect of printing and proofing.

the quality of the film directly affects the effect of printing and proofing. First, it is necessary to ensure that the dot percentage of the film is accurate, and second, it is necessary to ensure that the density value of the film at 100% is within a suitable range. Shangpin company sets the density value of the film at 100% as between 3.8 and 4.5. Why is this required? If the percentage of dots displayed in the computer is 50%, and the percentage of film dots is only 45% or 55% after the film is produced by the Imagesetter, it indicates that there is a problem with the control of the Imagesetter, which is bound to reduce or increase the proofing dots and fail to restore the original

the requirements of proofing are: 3% points are not lost, 95% points are not blurred, and the PS version is not dirty, but these three points are contradictory. The film density at 100% is too high, which is easy to make about 95% of the dots in the image paste into a piece, and the image shows a black pimple, just like human hair can't see hair silk locally, only a black piece can be seen; If the density at 100% is too low, it is easy to lose points below 10% when printing. Some people will say that if the density of 100% outer film is too low, reducing the exposure time of PS version can also make 3% points not lost, but at this time, PS version will definitely appear floating dirt. Therefore, it is necessary to adjust the density value at the best 100% point according to the exposure time and development and fixation of the PS version and plate printer used

the Phototypesetter has fast film sending speed and very accurate point percentage control; However, the speed of the electric extension is slow, and the point percentage can only control a few points, but the point shape is good-looking. Shangpin company rarely uses the electric extension to send films now, mainly because the percentage control of the electric extension point is not very accurate. Although the point shape of the Phototypesetter is not very good, as long as the appropriate PPD is selected, moire can be avoided

the tools to detect the film quality are: transmission densitometer, self-made signal bar, and the signal bar after various typesetting software produces the film. The purpose is to detect whether the percentage of points set in the computer file is faithfully displayed on the film, and whether the density value at 100% of the film meets the requirements of proofing