The connection between the most urgent procedures

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Connection between processes and image quality (II)

II. Importance of color proofing and calibration of proofing process

1. importance of color proofing. Color proofing is one of the most important quality control tools and plays an important role in printing

it takes a lot of time and money to print a sample on the printing machine, which requires the consumption of film, printing plate and printing. It is an expensive measure to see the printing effect of the color separations. If you are not satisfied with the printed products, you have to make the color separations again. In addition, when operating on the printing press, the printer is wrong without a template, which is like building a house without drawings. Therefore, the purpose of color proofing is to check whether the color separations are correct and to check and predict the printing results before printing

color proofing is to simulate what a set of color separations will look like

this simulation should accurately show the visual effect of the final print, not necessarily the exact correspondence of points on the film. It should indicate the dot increase that will occur in printing. The accuracy of proofing must be guaranteed. If the proofing method adopted is stable and controllable, accurate proofs can be made

proofing has many uses. First of all, with proofing, there is a challenge to the color separation process. The film provided by the color separation personnel cannot be said to be "qualified" immediately without proofing inspection

the stage of making eye-catching film is essentially to complete a process of color approximation. The color separation film produced should at least be able to achieve the effect of printing, imaging and proofing. At this stage, imprecise proofing methods such as thermal sublimation proofing can be used

mechanical proofing can be used in the final stage, which is an accurate simulation of printing methods. It shows that the printing method can reproduce images such as samples, which is the effect expected by customers

do you know more about it? In the case of picture composition, sometimes it is necessary to check whether the composition elements are complete and whether the positioning and registration are accurate through proofing. This proofing is usually not to evaluate the accuracy of color reproduction data display

2. types of color proofing. Proofing is usually divided into soft proofing and hard proofing. Hard proofing is an actual sample, which is easy to carry and transfer. Hard proofing can be made on the proofing machine with paper and ink, or it can be a pre proofing, but they are all made with color separations. There are different types of hard proofing, some are laminated films, some are in the form of leaflets, and some are polished to simulate the gloss of printed products. The page assembly system can use the stored data to produce the so-called direct digital hard proofing through photographic exposure. This proofing can be point image or no point

soft proofing refers to video display proofing, which is used to evaluate the data related to the original. It is often referred to as the rapid inspection method, which has a variety of uses. For example, it is used to quickly evaluate the adjustment results of the color separation machine; Evaluate the image corrected by the color system; Check the composition of several images or the film images provided; It is also used for color separation adjustment and consistency control

mechanical proofing. Mechanical proofing is to print actual samples with paper and ink on the proofing machine. If the paper and ink used for proofing are different from the actual printing, then the printed samples are inconsistent with the printing effect; The difference between the structure of the proofing machine and the printing machine is also an influence parameter. The printing effect of a single sheet proofing machine may be different from that of a web printing machine, and the effect of a single color proofing machine may not match that of a four-color printing machine. Nevertheless, mechanical proofing is still an effective proofing method, which can simulate the printing effect of a printing machine. One of the important developments of color proofing is the application of special proofing machine, which makes the proofing speed faster. At present, the common platform proofing machine and fast change rotary machine are such models. Four color sheet fed printing machine is often used to simulate the effect of web printing machine, but its point increase is smaller than that of web printing machine, the time consumption is longer, and there is also the cost of plate making and plate making

pre proofing. In the 1960s, pre proofing became popular. The color key color chip lamination proofing invented by 3M company is a representative one, but not all people can evaluate the color chip and judge the final print based on this kind of sample. This kind of proofing is to expose and develop various color films with color separations, and then stack and register them on a piece of paper in sequence to obtain a color proofing sample

DuPont invented the proofing method of Croix color powder for single sheet paper; 3M introduced their transfer key and matchtimmt single sheet color proofing methods. There are many proofing systems in the market, but the matchprint and Du of 3M company can run these production lines 24 hours a day, 7 days a week. The cromalin system of Bang company is an effective system and a standard for transmitting high-quality color information

the industry is still looking for a faster and economical color proofing system. The color separation machine makes color chips within 15min, but the time spent on making hard proofing is doubled. If the time for evaluation proofing is added, the production process will be greatly delayed. If the color separation results are unqualified, the time will have to be further extended

photographic color proofing. This proofing method was proposed again in 1986. It is exposed with the color gloss negative contrast paper, and then developed in an automatic developer. This system has a programmed exposure component, which can complete the exposure process within 5min. When the first proofing is processed in the developer, the second proofing is exposed. This system has advantages in newspaper printing proofing

soft proofing. Since the launch of the first page layout system by saiangel, soft proofing has been put into use. This system can observe simulated printing images on the color display. After the color separation machine scans the original, the color separation information is recorded in the disk, and the disk is connected with the color video display. The standard of saiangel system can be increased by 91% compared with that before; However, the orders of thermoforming machines decreased by 34% compared with the same period last year, and the scanning, observation and storage of image files. If you are not satisfied with the color separation, you can correct it. The video display color proofing device produced by the color separation machine manufacturer enables the color separation personnel to check the adjustment through rapid low resolution scanning. If the adjustment is correct, the color separation machine will be adjusted to the standard grouping power to record all image details; If you are not satisfied with the adjustment, you can change the adjustment and repeat the scanning. This kind of proofing method can avoid the waste of film, but in most cases, it is necessary to make hard proofing with color separations

Kodak has developed a pre observation electronic image network system. This system has at least two video displays with modems, which enables the operator to transmit the pre proofed image to the video display on the customer's side. The customer and the operator can talk with each other to decide whether to make some changes in the image, even at a long distance. Obviously, it is meaningful to save production time, proofing materials and reduce costs

In the 1990s, the color desktop publishing system developed rapidly. The WYSIWYG operation mode made the soft proofing method a standard function of the color desktop system

it needs skills to observe the soft proofing image, because the image from the observed image to the image to be printed can only be transmitted in one person's brain; The phosphor of the display cannot match the printing ink completely; There are differences in lighting between soft proofing and hard proofing; The resolution of the display is obviously lower than that of the printing method. The video display has only 512 or 1024 pixels per line, and the vertical resolution is roughly the same, which often makes it difficult to evaluate the details

direct digital hard proofing. It is directly generated by the pixels stored in the composition system, and the color hard proofing is generated by the color matrix printer. The resolution of the obtained sample is very low, and the color quality does not match the printed matter, but it can explain the correctness of the image file. To see the effect of printing eye tone, you can simulate it by exposing a piece of color photographic paper on the proofing recorder of hull company

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