Printing ink setting skills in the hottest Photosh

Printing ink setting skills in Photoshop

in DTP system, there are many occasions that it is necessary to convert RGB color mode image file format to CMYK color mode, so that color image files can be used for printing and copying. Under normal circumstances, Photoshop software is used to convert color mode. Because the two color modes are quite different in the way of color rendering, they show great differences in image quality, and in the process of color mode conversion, this difference is changed according to the settings of Photoshop software in printing inksetup

generally speaking, the difference of image quality changes significantly in two aspects:

1 Because the color gamut performance range of CMYK color mode is significantly smaller than that of RGB color gamut, it may produce "super gamut color" in some color gamut after converting to CMYK mode. The existence of this part of "super gamut color" will make the printing color seriously gray

2. When the printing ink and printing method, two typical cases of viggs in this regard, are COMAC's efficient and durable aircraft floor support items that can be used for the new regional jet ARJ21, the image hierarchy is lost. Especially in the level of dark tone range, the loss is more serious. Because dark areas are often areas where "super gamut colors" often occur

therefore, it is necessary to pay full attention to and discuss the setting of printing ink. In essence, this part of work is part of the debugging of electronic color separation machine and high-end scanner. In particular, the scanning software of some color plane scanners are installed under Photoshop software Printing ink origami includes the following three contents: color ink, dot gain, and grey balance. In essence, the color ink here refers not only to the ink for printing, but also to the pigment used by the inkjet printer through the option. Due to the different hues and printing conditions of printing inks and pigments, the differences in image quality are caused by different color forming methods, dot enlargement and neutral gray balance. Therefore, it is very necessary to adjust the data of the above factors to ensure the image quality. These data are only valid in CMYK color mode

I. grey balance

in the theory of pigment subtraction, equal amounts of cyan (c), magenta (m), yellow (y) and tricolor materials are mixed, of which grade 8.8 and above bolts are made of low-carbon alloy steel or medium carbon steel, and after heat treatment (quenching and tempering), black (k) will be obtained. However, because the pigments cyan, magenta and yellow can not get the ideal color from processing and manufacturing, they often have different degrees of opposite colors in cyan, magenta and yellow. For example, there is a small amount of magenta in cyan pigment, and a small amount of red in magenta pigment. However, yellow pigments contain a small amount of red. And in actual printing, due to the different ink brands used, the yellow, red and green ink colors are also different. For example, magenta, magenta, or peach are used in magenta ink, and medium yellow or transparent yellow are used in yellow ink. Therefore, after mixing the same amount of cyan, magenta and yellow inks, you cannot get a black with reddish brown. If you want to get a relatively pure black, you need a combination of cyan, magenta and yellow inks in different proportions

such a combination of different proportions, not only in the black area, but also in the gray area, it also needs different combination data of cyan, magenta and yellow. This is because the chromaticity law of dots is not exactly the same in the three areas of highlight (0~25%), intermediate tone (25%~75%), and dark tone (75%~100%)

gray, which is composed of cyan, magenta and yellow dots in different proportions of the three primary colors of ink in each area, is called neutral balance data in prepress and printing. Due to the sensitivity of gray areas to color performance, generally, when the neutral gray balance data deviates from the normal state, its gray will be biased to a certain color. Therefore, in the whole process of image reproduction, neutral gray balance data is regarded as an important quality standard to monitor the production process from prepress to printing. If the gray area of the original deviates from the normal data of cyan in the image scanning operation, the whole picture will be red due to lack of blue. During the printing operation, when the amount of ink in a certain color is too large, the printing picture will be biased towards the hue with large amount of ink in the gray area, which will disrupt the balance of blue, red and yellow ink in the gray area, thus causing the color bias of the whole picture

under normal circumstances, the correct data of neutral gray balance blue (c), magenta (m), yellow (y) and black (k) should be obtained through traditional proofing with specially designed color block group. The color block group is composed of different tonal areas with points ranging from 2% to 100% and different data of C, m, y and K. Confirm that it belongs to the color block group of neutral gray by observing the sample. Thus, the point proportion of each tone in neutral gray balance can be determined, and the curve between the reflection density of each tone and the data of points c, m, y and K can be drawn according to this. In general, the neutral gray balance data is about 7%-8% higher than y and m at 50% of the middle tone area, and about 5%-6% higher than y and m at 90% of the dark tone area, while in the high tone area, C is about 1% higher than y and m. From the perspective of neutral grey balance curve, y and M curves basically coincide, while from the perspective of neutral grey balance curve, y and M curves basically coincide, while C curve is higher than y and m and becomes an arch curve. Even due to the difference of ink hue, the difference range of Y and M curves will not be too large

however, in the "printing ink setting" item, it is impossible to enter the percentage of neutral gray balance points in C, m, y, K as in some scanners, and only the y value of CMYK color curve can be entered in the gray balance column. Therefore, if you want to accurately obtain the neutral gray balance data, you need to calculate the y value of each color curve based on the neutral gray balance curve you draw, and then input the data of each color. The correct neutral gray balance will be conducive to the correct color formation when RGB images are converted to CMYK color mode. Therefore, carefully balancing the data of neutral gray balance will ensure the improvement of image quality

second, dot gain

dot gain is an inevitable result of the printing process. At present, the conventional printing used requires the printing plate to absorb the ink, and then use the pressure to imprint the ink on the paper, such as relief printing, flexographic printing, gravure printing. Or "after absorbing the ink from the printing plate, it is first transferred to the blanket, and then transferred to the paper through embossing, so as to complete the printing, such as offset printing, which is currently the most used. Therefore, all printing must have three conditions: 1. The ink needs to have a certain viscosity, so that it can absorb the printing plate, and there is enough ink. 2. There must be enough pressure to transfer the ink to the paper. 3. Paper must have proper ink absorption capacity. Only when the conditions of pressure, ink volume and paper sheet match each other can we get satisfactory printing. The problem is that the imprint is enlarged due to pressure. How to control it within a certain range in printing and how to give advance compensation in prepress operation are important points

in any form of image printing, these extremely flat equipment are currently used in the lithium battery system of German small cars. Dots are not only a basic unit for receiving ink volume, but also a basic unit for printing. The transfer of dots in the printing process and the expansion it produces are bound to change the state of dots. This state change will seriously affect the image quality