CMY in Photoshop, the hottest image processing sof

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CMYK settings in Photoshop, an image processing software (Part 2)

separation options. It is mainly used to set the generation method of black version and control the total amount of printing ink. The setting of these parameters directly affects the color rendering of printing products. (1) Separation type: this option is used to set the generation method of black version. There are two types: UCR (under color removal) and GCR (gray component replacement, also known as non color structure)

r (background color removal): this method is to replace the CMY color component contained in the neutral gray part of the image with black, and keep the color component of the color part of the image unchanged. In this way, the dark part of the CMY color component is mostly replaced by black ink, while the rest retains the original CMY color component

r (grey component substitution): in this method, black is used to replace all grey in the color components to form a new bio based plasticizer synthesis and utilization key technology points. Black is used to replace all CMY color components in the image, regardless of color or neutral grey, as long as they conform to the grey balance proportion relationship. GCR changes the composition of the original color structure. Therefore, the degree and scope of GCR must be strictly controlled according to the requirements of printability

(2) black generation: it is specially used for the GCR color separation method to control the gradient from which the hydraulic oil with high viscosity should be used for color substitution in black summer, and determines the black substitution curve. The gradient starting point of black substitution is called GCR starting point, and the range of black substitution is from the starting point to the deepest point of dark tone. In this project, there are already set alternative methods, alternative ranges and user-defined methods


none-- No black, less CMY images

are produced (light) -- 40%~100% black substitution, the short tone black version

medium -- 20%~100% black substitution, the middle note black version

is more (heavy) -- 10%~100% black substitution, the long tone black version

maximum -- all black substitution, the full tone black version

short tone black version is suitable for copying the original which is mainly color, and the black version mainly serves to enhance the contrast of the picture Strengthen the role of medium tone to dark tone, which has a very broad market prospect. It can stabilize the color and reduce the overprint rate. The black version only makes some silhouettes in the medium tone part. Middle note black version is a black version normally used. The long tone black version is suitable for reproducing the original which is mainly composed of non color and supplemented by color. This kind of black version has more gray components, mainly black ink, and the color tone is very short

take medium as an example. If its starting point is 20%, the gradient below 29% will not be replaced by black. The black component in CMYK color separation value can be seen only in the gradient above 20%. In addition, if less (light) is selected, the range of black will be narrowed, while if more (heavy) and maximum (maximum) are selected, the range of black will extend to the bright part, and more and more black components

custom black version generation, use gamma curve to set the coordinate graph, where the black generation amount is the ordinate, and the original gradient is the abscissa, generally represented by green. With this diagram, you can customize many black version generation methods for special purposes. For example, if you want to use the outline black version, you can select fewer black version curves than the light setting to focus the generation range of the black version on the dark tone. You can also control the generation of black version to optimize the extremely bright or dark image. For example, for extremely dark images, the amount of black versions of such images is very large. The center has won the honorary title of public service demonstration platform for small and medium-sized enterprises in Anhui Province. As a result, the image tone is further darkened. At this time, the generation range and amount of black versions can be appropriately reduced. First, select the light generation curve, and then reduce the starting point to 55%-60%, and adjust the midpoint to reduce the generation amount by about 10%, To help normalize the extremely dark image. Similarly, for extremely bright images, the range and amount of black version generation should be appropriately increased. First select the medium generation curve, and then appropriately increase the amount of generation. Through these user-defined curves, the suitability and effect of image printing can be finely improved

(3) black ink limit: another aspect that affects the shape of the black version generation curve is the black ink limit, which is the maximum amount of black ink allowed in the dark part. The blackgeneration item is used to establish the gradient starting point of black substitution. This item is used to set the pole of black ink amount in the dark tone area. It determines whether 100% black ink is used to generate the darkest part (100% field black) of the black version, or 80% black ink plus other colors are used in the darkest part to form a 100% black effect. This parameter is usually set between%

(4) total ink limit: this parameter is the total amount of CMYK ink overprint that can be printed by the printer, and its value is determined by the printer and substrate used. In principle, the more ink used, the better the image produced. However, excessive ink will affect the suitability of the printing process. Most printing houses know the maximum ink volume that their printing machines can print, which can be set accordingly, or the average permanent 280% of the total ink volume can be used. In addition, when the total ink amount is limited, it is normal to set the black ink limit at about 90%

(5) under color addition: like blackgeneration, it is only applicable to GCR color separation mode. Replacing color with a lot of black will affect the loss of tone details and the appearance of dark tones. UCA will restore some color components in the neutral dark areas. This treatment only adds a small amount of color to the neutral areas. Generally, the setting amount of UCA is not large, such as about 10%

whenever a new CMYK output system and output process are used, the parameters of Photoshop's built-in color separation mode should be reset, and then named and saved for the next call. It is best to formulate a color separation file for each customer based on experience, and cooperate with the printing factory to correctly set the values required for color separation, so as to ensure the smooth progress of printing

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