Computer Graphic Design and Prepress Graphic Processing 500 Questions (48-53)

48. What is color has nothing to do with the device?

Color and device independence is an important part of the standard for implementing image information exchange. Its meaning is the result of image color data obtained by a certain image processing device, and it should be able to be restored accordingly on another processing device. To achieve color independence from the device, one must first be able to objectively evaluate the color and density of the image and the transformation characteristics between the processing devices.

49. How to implement color management in the color management system (CMS)?

A: Devices used to create colors include scanners, monitors, desktop printers, and printers, each of which can reproduce a limited range of colors. We call a device a color that can be reproduced as a color table. Many devices' color tables are recorded in a culture called "Profile." The color management system retrieves the device's color table from this file. The color management system will convert a device's color table to a device-independent color mode, the CIELab color mode, and then perform device color mapping to embed the converted device-independent color information in another device. In the color table, the device's color table can be matched. There are two ways of coordinating chromatograms for different devices: one method is to preserve the relationship between colors by transforming all the colors into the chromatogram of the device; the other is to map the colors outside of the chromatogram to the device's ability to produce In color, the relationship between colors is not preserved.

50. What are the color management processes?

A: An ideal color management process is as follows: 1. Determine the color performance of the monitor. Some color management systems preset the monitor color profile provided by each manufacturer together to form a comprehensive internal preset file. Profile library, called when determining the color characteristics of the display. 2. Calibrate the monitor. Adjust the monitor's white point and other display characteristics to meet your output requirements. For example, if output to a print medium, then the white point of the display may be calibrated to the color temperature of the printed paper. 3. Determine the characteristics of the scanner or other input device. If the color management system provides an IT8 sample, it can be scanned or photographed. Then compare the obtained color value with the standard color value, and record all the difference information as the profile file of the scanner for use in scanning. 4. The color management system converts the scan results to the monitor's color space. 5. Determine the characteristics of the color print and output device. That is, a color profile is selected for the color printer supported by the color management system, printing conditions, and other output devices. 6. The color management system uses the profile of the monitor and printer to change colors, and some systems allow "soft proofing" on the screen (ie, CMYK colors are represented on the screen).

51. Why is the color management of the monitor particularly important?

A: Although the monitor is a computer output device, it is an important reference window for designers to adjust colors, collaborate with colors, observe image depth, and adjust levels. Although we all know that there is a gap between the color on the display and the printed color, the judgment on the level, depth, and clarity of the image is based on the display of the monitor, because we cannot have the color of each pixel. All data is interpreted. Second, the display is the visual center of the design, regardless of the color mode of the image, it must be reflected on the display. As shown in Figure 1 (figure omitted). The digital image of the RGB color mode is required for the display performance, and the digital image of the CMYK color mode is also displayed on the display through the conversion. The two color mode images of the same file may have different colors on the display.

52. Why not set the resolution in typesetting and graphics software?

A: The typesetting graphics software is an object-oriented software. Expressions of text and graphics are expressed in the language of the algorithm. The objects produced are incapable of resolution, and they are output at the output device resolution. If the resolution of the output device is high, the resolution of the graphic output of the production page is high. Therefore, graphics software and layout software do not set the resolution. The images imported by the layout and graphics software are read from the original image when output. This is related to the resolution of the original image.

53. What is digital proofing?

What kind of digital proofing is the most reliable? A: Digital proofing is to print proofs directly from the computer before printing or designing the document output, instead of using the traditional proofer ink to simulate proofing. There are many digital proofing methods. The digital proofing program introduced by different manufacturers is not the same. Can roughly be divided into the following categories: 1 direct output inkjet proofs: This method is the simplest, directly driven by the printer to print the file. However, since the inkjet printer's ideas are diffused, the colors are bright, and the proofs are far from the printing results. 2 The second use of color management, and then use the inkjet printer output: this method of color and printing color is closer, but because there is no RIP interpretation, and printing is still some gaps, and error prone. 3 After using RIP to explain, use the inkjet printer to output the halftone dot: This method is because the RIP and the printing plate are the same time, and can find related errors with high accuracy. 4 The same RIP as the printing film or printing plate is used, and the dots are represented by a color layer using a transfer method, such as DuPont's proofing method.

"Guangdong printing" 2004 5 Author: Wuhan University School of Journalism and Communication