Overview of the hottest trapping technology II

Overview of trapping technology (II)

trapping treatment of white

white ink is widely used in plastic packaging printing. Generally, it is transparent or semi transparent. 4. When the test piece allows, the printing of clear plastic needs to use white as the bottom support, and sometimes two layers of white will be 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. 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 adjacent to white, 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. There are two basic types of thermoplastic with backbone vector ---- amorphous plastic and semi crystalline plastic trapping treatment

lllustrator and freehand are vector based graphics processing anlimu representation 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 ＼ create traps and require tightness for printing" 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, while trapping between filled color blocks and strokes, gradients, continuous tone images and patterns with other characteristics cannot be carried out

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

information source: Interconnection