Detailed explanation of the hottest trapping techn

Detailed explanation of trapping technology (Part 2)

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

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, relatively small black and gold blocks can be 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 overprinting in my powerful motherland, 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. When the black and gold lower the white, the white can retract 0.5-1mm to the black and gold

4. if the color block is light or normal, the amount of white retraction should be small or not retracted. 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 recycled with white, it is also unprofitable. PetroChina has invested 1.5 billion yuan and the annual output of 50000 tons of rare earth petroleum cracking catalyst project has started construction, then white should be expanded by 0.2mm into the transparent color to avoid leakage

trapping treatment of common software

trapping treatment can be carried out manually or automatically in common packaging design software

1. Trapping processing of backbone vector

lllustrator and freehand are vector based graphics processing software, which can generate simple automatic trapping objects, and the function of automatic trapping is basically the same, both of which are to create a separate light color overprint filling area to cover adjacent color blocks; They can judge when trapping is needed between adjacent two color blocks and when it is not necessary, and can only trap the selected objects

open the "trapping" tool panel in the "path finder" command under the "window" menu of lllustrator software; Call up the trapping function panel in "plug-in function creation trapping" of freehand software. The options are described below

width (lllustrator/freehand): refers to the width of the trapping area. In lllustrator, the default value is 0.25points, and the range is 0.01-5000points; You can enter units in freehand, such as 0.2mm

lllustrator/freehand: refers to reducing the proportion of bright colors in the trapping area to reduce the discoloration in the trapping area. The default value is 40%

lllustrator/freehand: refers to changing the trapping direction to expand the dark color into the bright color area

in lllustrator and freehand software, automatic trapping can only deal with trapping between adjacent filled color blocks, but not between filled color blocks and patterns with strokes, gradients, continuous tones and other characteristics

lllustrator and freehand software automatically trap according to the brightness of the color, and the trapping rules are as follows

(1) all colors expand into black

(2) bright colors expand into dark colors (including spot colors and other colors)

(3) the arrangement of primary color brightness from deep to light is m, C, ya, that is, when magenta filling is adjacent to cyan filling, cyan expands to magenta, which is just opposite to the trapping method when printing color sequence is arranged according to K, C, m, ya, which should be paid attention to

2. Trapping processing of base bitmap

trapping processing in Photoshop is carried out under the trapping command in the "image" menu of the software, which has only one option of trapping width

photoshop software can only trap by expanding the color, and its trapping rules are as follows

(1) all colors expand to black

(2) light color expands to dark color

(3) yellow expands to magenta and cyan

(4) equal expansion of cyan and magenta, that is, mutual expansion

in addition, the following matters need to be paid attention to

(1) the continuous tone image itself does not need trapping

(2) the trapping tool can be used only when the pattern is pressed on the platform layer

(3) there will be a fracture at the corner when trapping the color block and the color block

professional trapping software

professional trapping software is a powerful tool to solve trapping problems. At present, many rip provide inrip trap function, which is an open trap function in rip. However, this trapping method sometimes can not achieve satisfactory trapping effect, nor can it be corrected manually; If the design draft needs to be trapped in more or more complex places, trapping with Rip is often an unpleasant waiting process

there are also some professional packaging design software, such as packedge, ArtPro and other software, which also have powerful trapping modules, but these trapping functions can only be used in their own software system. Users must purchase software and trapping modules at the same time to use the trapping function. At present, these software have not reached the level of popularization for a large number of design and prepress publishing workers

now, Esko graphics company has launched a new deskpack software, which mainly solves various problems existing in trapping at present

first of all, deskpack provides plug-ins embedded in tlillustrator, which can directly perform various operations and controls of trapping in lllustrator software. Its trapping function module (trapx) is very powerful

1. using the latest trapping engine colorstitch based on brightness, it can quickly and accurately handle all trapping work in packaging design, and all places that need trapping can be completed quickly with one command

2. It can deal with the trapping of graphics, text, special filling, gradient and images well, especially when dealing with the trapping between gradient and adjacent color blocks. It can trap in the form of gradient conveniently to avoid the trapping place being too stiff

3. the user can flexibly generate the trap layer alone. It is a highly interactive way to easily and modify the trapping content while keeping the original file unchanged. Humanized trapping tool

4. trapping parameters can be set and controlled according to the printing process

5. The trapping work of a manuscript can generally be completed in a few minutes through the trap command. If local corrections are made, the update can generally be completed in a few seconds

secondly, deskpack software is for the vast number of lllustrator users. Ordinary prepress personnel can master all the functions of the software in only one day. Easy to learn and use is another feature of it. Source: Henan printing art