Key points of quality management of the hottest di

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Key points of quality management of digital plate making system

first, the scanning input part - the re digitization of foreign films

because the whole process of computer direct plate making is fully digitalized, the foreign color separations must also be able to be rescanned into numbers for plate making, which is commonly known as point scanning technology (Copydot). Its main characteristics are:

point copying: that is, the original film is re copied, Become an electronic document that can be combined into a larger version

digital subtraction: that is, the four-color film is merged and processed to restore it to a color image while retaining the details of the image. The modified documents can be processed with various software

second, comprehensive color management

because digital color proofing must be used in computer direct plate making, how to simulate the actual printing effect with digital color proofing is very critical. In addition, the screen display also needs to match the printing, so the color management of the whole system must be considered

CIELAB, the standard color space of the international lighting Commission, is independent of the equipment and covers the entire visible color gamut. At the same time, according to the standards of the international color alliance, a relevant feature file profile is defined for each device to describe the color characteristics of the device

the basis of color management is to ensure that all devices are in the color reproduction system. To achieve the goal of color management, equipment calibration, characterization calibration and color gamut conversion are essential in this process

equipment calibration: some people think that the term "equipment calibration" refers to all steps of obtaining accurate colors, which may mean that the copied colors are calibrated to match the original colors. But in fact, calibration equipment is only one of the three steps of color management. The equipment calibration itself can not guarantee the color matching. It only calibrates the performance of the equipment itself, and can only ensure that the equipment (such as scanners, monitors, printers) meets the standard indicators, providing a way to ensure that it works stably for a period of time

profiling: it is a way to measure and quantify the color space, gamut and color characteristics of a specific device under known conditions. It is used to determine how colors are collected or recorded when an input device or an output device is calibrated. Characterization calibration is the process of actually generating device description files such as scanners, displays, printers, etc. The characteristic calibration data is used by the color management software, so the characteristic calibration is a process of describing the color gamut of the equipment in cooperation with the color management software. To realize the characteristic calibration, the equipment itself needs to be equipped with high-performance color sensors and matching color management software to realize the real characteristic calibration; Otherwise, these devices must cooperate with the color management software with the help of separate calibration devices in order to achieve characteristic calibration

gamut conversion (color transfer): This is the process of converting image color from gamut data of one device to gamut data of another device. Through the color management software, the color gamut conversion can be realized manually or automatically. The conversion between the color gamut of different devices is usually called gamut mapping

III. electronic blockbuster

modern printing has increasingly stringent requirements on the time of plate making, the standard of old materials, and the implementation and use of new materials. In order to ensure the timeliness, the effective working hours of weekly magazines are calculated in hours from the deadline of manuscripts to the listing of magazines. In the traditional way of plate making, it is done by the plate making workers in the plate room by hand. Its quality and speed are greatly limited. The emergence of CTP technology makes the combination of electronic block printing technology and large-scale prepress productivity more and more important

electronic composition is a composition process that arranges pages in the order of binding pages after printing for books, magazines, picture albums, number books and other books and periodicals. With the wide application of electronic plate making technology, it plays an obvious role in ensuring the quality of printing products. At present, magazines on the market often have inaccurate rules for individual color pages, which seriously affects the printing effect. Time is not tight, you can rework. If time is tight, you have to let it go. From a technical point of view, the current phenomenon will be solved with the application of electronic version making technology. Compared with the traditional way, electronic mosaic has the following advantages:

(1) manual mosaic uses scissors and tape, and the time and accuracy are difficult to guarantee. Computer jigsaw is to make up before color separation, which saves time and effort and is efficient

(2) general computer compositor can easily spell a version in more than a minute, which is about ten times more efficient than traditional manual

(3) after multiple copies, the quality of manual patchwork is attenuated. Computer patchwork is an imaging, with high point quality and low material consumption

IV. digital color proofing

from the perspective of production, color printing quality is a process based on the point color principle, and production requires strict accuracy and stable repeatability. However, there are many factors that affect the printing color, such as the characteristics of paper, the thickness of ink layer, printing pressure, air humidity, and even the quality of plate making. Some factors will affect each other, and the increase or decrease of each factor will lead to changes in other factors, thus affecting the quality of printing color. Therefore, it is necessary to estimate the comprehensive effect of various factors on the print before production in order to make adjustments, and proofing is a production simulation before actual printing

generally speaking, proofing provides the following three functions: first, it is used to check the effect of color separation and plate making, to determine whether the color of the picture is processed correctly, and to provide a basis for revision. Second, it is used to check the technical requirements such as registration and dot expansion value of film, which can be used as a reference for actual printing. Third, as a communication tool, it will be signed and confirmed by customers before printing, and will be used as a standard for future receipt

the computer direct plate making system must adopt digital color proofing. Traditional proofing generally uses a monochrome lithography machine. Ink supply and ink mixing are decided by the master according to the situation, and the goal is to make the proofing effect pleasing to the eye. However, this practice often sacrifices the stability of proofing color, and less takes into account the requirements of printing. With the development of computer direct plate making technology in recent years, CTP needs a set of reliable digital process to properly handle the production process from plate making to printing machine, compared with the way of outputting film. With the maturing of image data technology, proofing has also begun to develop in the direction of digital. One of the most important contributions of digital proofing is to improve communication with customers. Before digital proofing, the film must be produced first, and then proofing. If customers are not satisfied with the color, they have to re produce the film and proofing, which often wastes a lot of money and time. With digital proofing, you can let customers see the proofs first, and then output the film when they are satisfied, which not only saves costs but also improves communication. You can even proofing while separating colors, which can be described as an important breakthrough in the printing process

v. server and raster image processor

the computer direct plate making system must have a fatigue testing machine. In addition to paying attention to the purchase, a powerful server and raster image processor can realize the centralized storage and archiving of large-capacity files and the management of print queue

ctp system does not use film, so digital proofing must be used. When digital proofing, such as the output of the final product, uses their own rip, there are often inconsistencies between the sample and the final product, so they are required to use the same rip. At this time, rip should have the function of "rip once, output many times", that is, the same data processed by Rip can be supplied to digital proofing and final product output at the same time, and rip is required to output data with different resolutions according to different devices. Using the data after the same Rip can make the proofing sheet accurately reflect the final finished product situation, and avoid or reduce the chance of color deviation and error

VI. quality of employees

with the continuous infiltration of high and new technology represented by computer technology and network technology into the printing industry, the personnel of the domestic printing industry are axz corrugated constant; The quality has been greatly improved in recent years, and the industry has a number of high-quality talents, which has also laid a certain foundation for the application of CTP technology in China

with the continuous development of China's economy, high-end printing is gaining more and more markets, and this trend is particularly evident in the more developed areas in eastern China. With CTP system, the prepress process is completely digitalized, so the quality of plate making and printing is better. After China's entry into WTO, the printing industry as a whole will gradually form norms and processes in line with international standards. The impact of the policy on the domestic printing industry is huge. The development of CTP in China will benefit from the gradual liberalization of the printing industry by the state

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