Although computerization has shortened the workflow, it has also caused many problems. One of the more ignoring ones is the trapping. This problem has existed since the time when the issue was drafted. As we step into computerized production, the problem of confusing whiteout is still very common. How serious is this problem in the process of DTP production? What is the problem of leakage?
First of all, “leakage†literally explains that it is leaking white, that is, some places that should not have white appear white. You may wish to pay attention to some printed matter. Between the color blocks and the color blocks, there may be a very thin white line. This line is not deliberately added, but it is the problem of white leakage mentioned in this paper. The cause of the problem is to talk about color separation films.
After the computer finishes the production, it outputs four color films. The four films are respectively C, M, Y, and K. Usually, the colors set on the computer are mainly C, M, Y, and K. The color settings on the computer determine the distribution of film images. For example, if C is set to 100% on a computer, the output color separation slice will have 100% black on the C slice. The problem of confusing white is created when the color is set. For example, four closely-arranged squares are set on the computer, and the four squares are assigned to the colors of C, M, Y, and K. Each of the four films output has a four-sided black grid. The four films went to the printing plant and put them on the printing press after the printing process. The four colors were printed on the paper at high speed. Because the paper needs to run at a high speed on the printing press, the edges of the grid and the grid can not be close enough to reveal the paper color. Such a white line is called "leakage." With the "leakage" of the natural need to remedy, there is a "trap leak" work.
Trapping begins with the computer first. The simplest method is to set an additional border line when setting the color, and use Overprint for the border line. With this line, even if there is a walk during printing, there will be no white line, only a dark line. Trapping work may seem simple, but if the layout is large and complex, there will be mistakes. In case of a demanding guest, the color of the trapping line is also an elegant issue. If the blue is yellow and then the line is the green line, this effect will affect the design of the layout. Do not appear green lines, and thus have a lot of trapping skills.
The most common trapping techniques are Spread and Choke. Spread (commonly known as "eating out") refers to the outward expansion of the color patch trapping white line superimposed on the peripheral block. The concept of Choke (commonly known as "ingestion"), in contrast to Spread, allows the outer stencil to expand inwardly. The use of the two trapping techniques depends on the depth of color, and it is best to superimpose them on dark colors. In the absence of certain things, in some cases, the trapping line may use the mixed effect. Mixed means that the color of the trapping line is the color produced by mixing two colors on the encounter plate.
Usually most of the software we use (such as: PageMaker, QuarkXPress, Illustrator, FreeHand, etc.) have built-in trapping functions, and these software can only do some trapping work of simple color blocks and color blocks. Gradient colors and images need to be trapped.