Remedial measures after the hottest leak

2022-08-13
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Remedial measures after white leakage

trapping is also called trapping, also known as expansion, mainly to make up for the white leakage between two adjacent different colors caused by inaccurate printing overprint

when people face printed matter, they always feel that dark color is close to people's eyes and light color is far from people's eyes. Therefore, when trapping the original, they always try to prevent the light color under the dark color from being exposed, while the dark color above remains unchanged to ensure that it does not affect the visual effect

principles of trapping treatment

the implementation of trapping treatment should also follow certain principles. Generally, it means to expand the lower color without expanding the upper color, expand the light color without expanding the dark color, and expand the flat without expanding the field. Sometimes it can also be mutually expanded. In special cases, it is necessary to carry out reverse trapping, and even add a gap between two adjacent colors to make up for the overprint error, so as to make the printed matter beautiful

the amount of trapping depends on the characteristics of the printing material and the overprint accuracy of the printing system. Generally, the trapping amount of offset printing is smaller, and that of gravure printing and flexo printing is larger, generally 0.2 0.3mm, which can be determined according to the printing accuracy or requirements of customers

common trapping treatment methods

there are four common trapping treatment methods

(1) monochrome line overprint method: add light colored lines on the edge of the color block, and select the line attribute as overprint

(2) synthetic line method: add synthetic line on the edge of the color block. The line attribute is not selected as overprint

(3) layered method: trapping is achieved by shrinking or expanding elements on different layers

(4) shift method: by moving the position of the inflection point in the color block to achieve internal contraction or external expansion, it is generally used in trapping related to gradient

the trapping amount of 0.2mm is taken as an example for discussion

1. when the color block is adjacent to the color block, the monochromatic line overprint method or synthetic line method is mainly used

(1) when the cyan block is adjacent to the magenta block (including various combinations of different point percentages), the monochrome line overprint method is adopted, that is, the line of the magenta block is changed into 0.4mm magenta, and the attribute is selected as overprint line. If the synthetic line method is adopted, that is, the lines of magenta blocks are changed into c100m100 lines of 0.2mm, and the attribute should not be selected as overprint lines. Here, the monochromatic line overprint method enlarges the magenta block to the cyan block by 0.2mm, while the synthetic line method enlarges the magenta block and the cyan block to each other by 0.1mm, which is a form of mutual expansion

magenta is adjacent to yellow. The situation is similar when cyan is adjacent to yellow, or add 0.4mm yellow line and select overprint; Or add 0.2mm m100y100 (or c100y100) line

(2) when the superimposed color of cyan, magenta and yellow is adjacent to the other color, including the combination of different point percentages, the trapping treatment adopts the monochrome line overprint method to maintain the annual growth of China's new material industry at about 25%, and the color block expands 0.2mm into the superimposed color

(3) red composed of fuchsin and yellow with different percentage points and green with different percentage points. When the green composed of yellow is adjacent, trapping must be carried out, otherwise yellow will leak out when overprinting is not on time. Magenta lines can be added to the red edge, and overprint lines can be selected as lines to trap

2. if the color block is composed of two primary colors or spot colors with the same size and position, and there is transparent or white around it, in order to prevent the overprint from leaking the next color and causing unsightness, the method of shrinking the edge of the next color can be used for trapping. If the color block is overprinted by two flat colors, or the previous color is flat and the next color is solid, trapping is generally not required, unless there are special requirements for printing

3. When the gradient is adjacent to the color block, it can be divided into the following situations

(1) cyan gradient and magenta. When yellow is adjacent, trapping is carried out according to the printing color sequence, and magenta or yellow can be extended by 0.2mm to cyan

(2) when magenta gradient is adjacent to cyan block, reverse trapping is required, that is, cyan is extended by 0.2mm into magenta gradient. When the magenta gradient is adjacent to the yellow block, normal trapping is carried out, and the yellow block is extended by 0.2mm into the magenta gradient

(3) when the Yellow gradient is adjacent to the cyan and magenta blocks, reverse trapping shall be carried out, and the cyan and magenta blocks shall be expanded by 0.2mm into the Yellow gradient respectively

4. When the continuous tone image is adjacent to the color block, there are two kinds of trapping: one is to expand the color block into the image; The second is to expand the image edge into the color block. When expanding the edge of the image, you can slightly enlarge the image according to the actual situation, or use image software to enlarge the edge of the image, or expand the mask of the image. When a four-color image is adjacent to one or several primary colors, trapping is generally not required. If the hue of the color block differs greatly from the hue of the image, trapping is required. For example, when a red tomato pattern is adjacent to a green block, the green block must be extended to the tomato pattern

when the four-color image is adjacent to the spot color, trapping must be carried out

spot color and primary color. Spot color and spot color. The trapping between spot color and gradient, spot color and image can be carried out according to the trapping principle and the above trapping method, which will not be repeated here

trapping treatment of special colors such as black and gold

trapping of special colors such as black, gold and silver generally follows the following rules

1. When black and gold blocks are adjacent to other colors, expand other colors into black and gold blocks, and can be expanded to 0.5 1mm

after a lot of industry research and study of foreign standards, 2. Generally, black and gold characters are directly overprinted on the background color

3. For the pattern with black and gold outline lines, the fill color of the pattern and the adjacent background color should be stacked in the middle of the black and gold lines to avoid uneven trapping

4. Generally, small black and gold blocks can be B. whether they can be clamped and directly overprinted on the background color; In order to save ink, larger black and gold blocks should be overprinted with the background color, which can extend more into the black and gold blocks

5. Although black and gold inks have strong covering ability, they also have a certain degree of transparency. When a large area of black and gold blocks are stacked on two different colors, in order to ensure a consistent visual color effect, black, gold and ground colors should be overprinted

6. When the black and gold blocks are directly overprinted on the background color, and there are white words or thin lines on it, if the black and gold blocks have a large area, the black and gold blocks should be made into overprint with the background color. If the area is small, the white words or thin lines can also be reduced to the background color to avoid the white words and white lines from blooming after printing

7. When black is adjacent to gold or silver, trapping can be carried out according to the color sequence of printing. Generally, black can be overprinted on gold or silver. If both areas are large, it is best to make overprint to avoid printing difficulties

trapping treatment of white

white ink is widely used in plastic packaging printing. Generally, in the printing of transparent or translucent plastic, white is needed as the bottom support, and sometimes two layers of white are supported. In order to prevent the white under the color block from being exposed due to inaccurate overprint, white retraction should be considered before printing

1. White retraction can be carried out according to the depth of its color or the requirements of customers, and the retraction amount is generally 0.2 0.3mm

2. if the color block is white and transparent next to it, white can be retracted by 0.3mm into the color block

3. White can retract 0.5 1mm to black and gold when white is under the support of black and gold

4. If the color of the color block is light or normal, the amount of white retraction should be small or ineffective. The more simple the retraction is. For example, when the dot percentage of the color block is between 30% and 50%, the retraction of white can be 0.15mm; When the dot percentage of the color block is less than 30%, white can not shrink

5. When holding white under the gradient pattern, the white should be considered to be retracted obliquely. The cyan gradient is supported by white. The white in the deep cyan is retracted by 0.2mm, and the white in the light cyan is retracted by 0.1mm, which can be realized by the method of inflection point displacement

6. if the transparent color (no white under the ink) is adjacent to other colors, the white under other colors should be retracted by 0.2mm; If the transparent color is directly adjacent to white, white should be expanded by 0.2mm into the transparent color to avoid leakage

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