Application of color image and color separation technology

Commonly used color images are images of the RGB color model. Color separation is the decomposition of color images into cyan, magenta, yellow and black color grayscale maps, so color separation technology is the first to convert various colors in color images from RGB color model to CMYK color model, and then color The image is stored as a grayscale image of four colors of cyan, magenta, yellow, and black. It can be seen that the key to color separation technology is the color space conversion technology.
Based on the above relationship between the RGB color model and the CMYK color model, we obtain the content ratios of C, M, Y, and K required when a certain color on the original image is produced by the CMYK ink combination. The two models have the following relationships: C=F-R; M=F-G; Y=F-B where F is the full-color value.
For any color C, M, Y, if its component is not 0, there is a gray component whose size is min(C,M,Y).
In the actual printing, black pigment is added in order to make up for the defect that black formed by subtractive primary colors is not black enough. At the same time, the use of black pigment can also save a large number of color pigments, directly with the black pigment to form a different gray level, instead of subtractive 3 primary color combination. In this way, after the introduction of the black pigment, there will be redundant components of blue, pink and yellow. The content of cyan, pink and yellow in the actual printing must be reduced by the content of the portion replaced by the black pigment. Therefore, the conversion relationship between the RGB color model and the CMYK color model requires several explanations for this conversion relationship:
(1) The gamut of the RGB color model has a larger color gamut than the CMYK color model. Some color combinations of the RGB color space cannot be represented by the color of the CMYK color space. When the conversion is performed, these colors will be cut off. Convert to similar CMYK colors as much as possible, so there is a one-time conversion problem.
(2) The conversion formula is only realized under ideal conditions. In practical applications, due to factors such as the characteristics and composition of pigments, the effect of printing after separating the images according to the above formula is difficult to meet the requirements of the application, and thus the color space must be The conversion coefficient is corrected to ensure the output quality of the color image.