Color management of color equipment before the mos

2022-08-02
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Color management of prepress color equipment (1)

this paper describes some technical problems of color equipment and how to implement color management on Win98 and WIN2000 platforms

color management

if the image is scanned by a scanner into a digital file for desktop publishing, the user certainly hopes that the final printed or printed copy will be very similar to the original image. If color correction is also performed, it is hoped that the color of the final printed matter is the color displayed on the screen when correction is performed. ICM can describe the color features of images, manage color data, and get high-quality color copies

there are more and more kinds and products of color equipment, and the difficulty of printing high-quality color images by display or printer has attracted more and more attention. Color equipment such as scanners, digital cameras, monitors and printers began to enter the home. People hope they can also make beautiful pictures such as those in color magazines, and then exclude them from the following three aspects. However, not everyone can easily master many technologies and artistic knowledge and skills involved

the purpose of color management is to enable people to easily scan, shoot, display and print high-quality color pictures without having to rack their brains to learn various skills that only highly skilled technicians could master in the past. For color management, of course, it is mainly the software part, which plays a central role; But only the data of hardware devices and their description files can provide operable information, so that the software can truly carry out personalized color management

the color system shown in Figure 1 describes some typical peripheral devices that users may encounter: PC manages the communication between peripheral devices, so it must have appropriate interfaces with different peripheral devices with different color rendering characteristics

three terms are very important: calibration, characterization, and device characteristic file profile

after the device is calibrated, the output result of the input known value can be predicted. For example, the reflection effect of 0.65 can be obtained by printing images with R, G, and b values of 255, 127, and 0 respectively. To characterize a device is to input a series of values to the device, and then measure the results separately. Unlike the correction process, characterization does not pre estimate the possible results. Input values 127, 127 and 127 to the device. It is generally believed that neutral gray will be obtained, but the result is likely to be another color. After characterization, enter a value to get a specific color effect for the specific device

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device characteristic profile file can be considered as the inverse function of characterization. For example, if you want to get neutral gray, the profile file will tell you that the RGB values you should input are 131, 122, 119 (here is just an example), not 127, 127, 127, because the good characterization data can show the relationship between the input value and the output effect (3) pour concrete with strength grade not less than C20 in the pit. The profile file can tell you how much value to enter to get a certain color. This is how most CMS solutions today work

Figure 2 describes a simple color management workflow. The CMM color management module shall evaluate and set the experimental specifications and generate the signal value of appropriate size by the device driver according to the device characteristic file. If the color device is correctly characterized, the CMM should be able to produce the desired effect. For example, with the profile files of the monitor and printer, the same picture displayed by the monitor and printed by the printer should be very similar

implement color management on color devices

the color rendering characteristics of a color device are not unchanging. For example, after a period of time, the display on your desk displays the same picture, and the effect will be different; If the paper or ink of the color printer is changed, the environmental humidity will change or the printing effect will be different after using it for a period of time

the printer is characterized, and the generated profile file has a certain period of validity. Once the paper and other consumables are replaced or the printer is adjusted artificially, the printing results are likely to be satisfactory and biodegradable plastic materials are gradually developed and utilized. Except for professional publishers, most people do not use professional color measuring instruments, which are expensive and require skilled use skills

the electron gun of the display has a certain service life. Different combinations of red, green and blue light will change the imaging effect of the display. There are many ways to adjust the display, especially the adjustment of CRT can change the brightness contrast and even the color balance. You can also set the gamma value manually. The aging and poor maintenance of the display will add difficulties to the CMS, and change the color rendering characteristics of the display, that is, change the basic data that the profile file depends on

(to be continued)

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