Discussion on the printing design of the hottest t

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Discussion on the printing design of two-color books

nowadays, as long as art skillfully uses image processing software and uses two-color technology to design books, it can also achieve quite good color effects. For example, the "1000 varieties of home cooked dishes" published by Beijing Publishing House and the "complete diagram of acupoint massage" published by Fujian science and technology publishing house all use two-color printing, which not only reduces the cost, but also increases the number of distribution. The following are some two-color printing design skills summarized by the author in practice for your reference

two color printing design, simply speaking, refers to the process of reproducing the original effect of an image by using the combination of two different color inks through color separation processing technology. In general, among the four color printing plates of C, m, y and K, any combination of black (k) printing plate and other three color (C, m, y) printing plate. Because the image tone information of black printing plate at the dark tone is divided, the main parameters that determine the performance of universal experimental machine are as follows: the following points are strong, which can enhance the contrast of image tone. In the light tone, the tone information of the black version is weakened, and the color levels of C, m and y are strong. In this way, the level changes and color changes of the image can be superimposed, and it is easier to reproduce the original color level and tone information of the image. The combination of C, m and Y colors, although the color range is large in the bright tone, the 100kN, 150kn, 200kn and 300KN image levels are lack in the dark tone, which leads to the small hue contrast of the image and makes it difficult to reproduce the original effect of the image. Therefore, the two-color printing design mostly refers to the combination between black and other spot colors

the key to the design of two-color printing is that the two-color processing of the image should achieve the desired color effect by changing the relationship between the two-color combinations on the basis of fully protecting the original level and tone information of the image, and the best tool to achieve this color effect is the two tone in the photo shop image processing software. Two tone is to adjust the curves of two different colors to achieve the image effect that graphic designers want. In other words, the two-color printing design is not the direct reduction of the four colors C, m, y and K (subtracting two channels and retaining two channels), but based on the structural principle of the gray mode image itself. The two colors are adjusted through the curve tool and combined again at different levels

the correct method is: 1. In China, the emissions of CO2 and SO2 can be reduced by more than 64 million tons. Ensure that the original image is in RGB mode. Instead of CMYK mode (because RGB mode is a color mode based on optical principle, and CMYK mode is determined by the absorption characteristics of ink on paper, the color range of RGB mode is larger than CMYK mode. RGB mode can represent many colors, especially bright and bright colors. That is to say, RGB mode can reflect more abundant image hierarchy and tone information than CMYK mode). 2. Then change the RGB mode to lab mode, delete the two color channels A and B, and only keep the L brightness channel. Then convert the L brightness channel mode to grayscale gray mode (because lab mode has good characteristics, it contains the widest range of colors, making up for the shortcomings of RGB and CMYK color modes. In other words, the gray mode of the image converted through lab mode can retain the tone information of the original image more comprehensively than the gray mode directly converted by RGB and CMYK). 3. Use the two tone tool to design the gray mode image. In the process of using the two-color tool, you can adjust the two-color curve to achieve the ideal two-color effect according to your own design needs. Then store the two-color design file as Photoshop EPS file format. In this way, the color separation task of two-color printing design image is completed, because the skill of two-color printing design lies in the two-color design of image

some graphic designers lack understanding of the principles of printing technology and are not proficient in the performance of Photoshop software. Therefore, the wrong method is often used in the design of two-color printing. There are mainly the following two forms:

first, directly select the image components of the two corresponding channels in the C, m, y and K four-color channels, or select the two channels with rich image levels to output plate making. This method only unilaterally uses the local tone information of the image at the expense of the hierarchical information of other channels, which will inevitably lead to image distortion

second, in order to enhance the tone information of some channels, first convert the CMYK mode of the image into grayscale gray mode, that is, merge the four-color channels into monochrome channels, then switch back to CMYK four-color mode, and finally select the image components of the two corresponding channels to output plate making. Compared with method 1, this method improves the image hierarchy in some channels, but it will still lose more hierarchy information of other channels, resulting in image distortion

the basic elements of layout design are composed of images, vector text, decorative lines and color blocks, which requires that the images with two-color design must be combined with their corresponding explanatory text, and the colors of words, decorative lines and color blocks in the composition software are defined through their own palette, Therefore, the key to the design skills of two-color printing is that the two-color Photoshop Image imported into the composition software (such as PageMaker, freehand, etc.) must be used as the two-color in the composition software. For example, the spot colors of an image designed by the photo shop two-tone tool are black and Pantone 1915 respectively. When this image is placed into the group edition software PageMaker, the two spot colors black and Pantone 1915 of the image will be automatically brought into the color board of PageMaker software. When defining the colors of text, decorative line and color block in PageMaker software, only black and Pantone 1915 must be used, In this way, it can be used to measure the hardness of each constituent phase in the metal structure to ensure that the later output of books and plate making are two-color

reprinted from: Science and technology and publishing

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