Nowadays, a large number of colorful, beautifully decorated, well-illustrated books, picture books, newspapers, packaging boxes, advertisements and other printed materials are flooding and embellishing all aspects of people's lives and become a necessity. The printing and copying of these color products is obviously inseparable from the theory of color. The color management theory already covers the entire process of printing and copying, whether it is pre-press color separation of printed matter, color synthesis during printing, or even post-press processing. The surface finishing of printed products is inseparable from the concept of color management. More importantly, color restoration has become one of the important factors to measure the quality of printing. 1 Review of color knowledge The reason why people can recognize colors is because they have the physical basis required for the formation of color vision, that is, color light, colored objects, and human visual organs. If these three are missing, they cannot form color vision. The color light mainly depends on the light source in the process of pre-press and printing. In the color science, the light source with a color temperature below 5000K is called a low color temperature light source, and the light source with a color temperature above 5000 K is called a high color temperature light source. When the color temperature is low, the color of light is reddish yellow; when the color temperature is high, the color is blued. In the prepress design and layout workshop, due to the need to scan the original, page color design and creativity, image color adjustment and other operations, the requirements for illumination light are high, and the illumination light also has a great influence on the color of the display, conditional Enterprises should equip all such workshops with standard light sources. The standard light source that meets the requirements of the printing industry's lighting standards is a class of specially made fluorescent lamps called high-color rendering fluorescent lamps. The standard light source in the printing industry must meet two conditions. First, the color temperature of the light source must reach 6500K; the second light source The color rendering index should be greater than or equal to 90. The basic elements of color that make up a color object are hue, lightness, and saturation, which are the three attributes of color. Hue refers to the appearance and name of the color. The commonly known "red orange yellow green blue blue purple" is the hue of different colors. Brightness refers to the degree of lightness and darkness of the color. The reason why the human eye can see the lightness and darkness of an object is because of the difference in the amount of light (heat) reflected by the object. The more light, the higher the brightness, and the lower the brightness. The lightness of the color of the pigment depends on the content of white and black in the mixed color. The saturation is also called the purity or saturation of the color. The simplest spectral color is considered to be the most saturated or purest. If a certain spectral color is mixed with white light, the saturation will be reduced, and the same will happen if the pigment is added with white saturation. 2 Reasons for introducing color management in the prepress field In printing and copying, we often refer to the phenomenon of "device relevance of color", that is, the same color is input on scanners provided by different manufacturers with the same two modes, and the color displayed on the display is obvious. Difference; similarly, there are obvious color differences in the output results of the printers provided by the two manufacturers with the same mode. Not to mention, in the entire color reproduction process, the same color should be in different Transfer between hardware devices, the original (mostly the principle of subtractive color formation, the digital manuscript page is the principle of additive color formation) after scanning, image processing (additive color formation principle), and finally print out the printed matter (subtractive color formation principle) . Due to the essential difference between the additive color forming principle and the subtractive color forming principle, how to ensure the consistency of the colors in the various process links of the printing and copying process, so as to achieve the purpose of controlling the color copying quality, the concept of color management needs to be introduced. Color management includes: 1) Color matching between different input devices; for example, the color of the same manuscript processed by different input methods. 3 Color management steps There are generally three steps to perform color management. The first step is Calibration, which means "calibrate the instrument"; the second step is Characterization, which is "characterization process"; and finally, Conversion, which stands for "convert color space". These three steps are simply referred to as "3C". 1) Calibration refers to adjusting the instrument to reach the standard state. All instruments must be calibrated before they can be used to ensure the normal performance of the instrument. Device calibration is to make the input and output devices use color description files to formulate and describe colors according to their respective characteristic curves, and it is the basis of the device's color rendering method as a feature description. Equipment calibration includes the following aspects: scanner calibration, display calibration, and output system calibration. After the device is calibrated, a device profile will be generated. The general scanner providers are equipped with their own color correction system when launching scanning equipment. Through these color management software, color compensation is automatically performed, which effectively solves the problem of color distortion of the scanned image, so that the color image has the best color effect. The operator can complete the calibration process of the scanner step by step according to the prompt of the management software. Computer monitor calibration uses built-in hardware and software to calibrate or uses built-in software and monitor auxiliary software to calibrate. Calibration steps: first, warm up the display to make the display glow in a stable state; second, set the brightness and contrast of the display, adjust the gray balance of the display; third, set the Gamma value, usually the recommended image is 1.8; Fifth, correct the white and black fields; sixth, calibrate the gamma value and gray balance; seventh, save the set values. Round Food Container,Disposable Plastic Round Bowl,Large Round Salad Bowl,Aluminium Container Box walson groupe , https://www.hagarbagebag.com
2) Match between the color of the original and the color of the display;
3) Color matching between output devices;
4) Match between the color of the display and the color of the printed matter;
5) Color matching between the original and the printed matter. Color management is to solve the problem of color conversion and matching between various devices. The main task of color management is to solve the problem of image data conversion in various color spaces, so that the color of the image is minimized during the entire production process. The basic idea is: choose a color reference space that is not related to the device, then characterize each device of the entire system, and finally establish a certain correspondence in the color space of each device.