Spot color prepress processing in direct plate making process

With the development of printing technology, four-color printing has not met the requirements of fine products for color in some aspects, and the application of multi-color printing is gradually becoming widespread. In our familiar desktop platemaking technology (CTF) process, multi-color printing can be used to detect whether the ink color matching, spot color ink, and four-color ink are adjacent to the edges of the adjacent areas by film, printing, and proofing. It is reasonable because the cost is low. Modify the document and film proofing, repeat the experiment to customer satisfaction and then print. In the computer-to-platemaking process, before the publication, we see digital samples. It will never show any color leakage or color reversal. However, in the post-process printing, even if a CTP version is issued, the error is inevitable. Errors can be compensated only by doing trapping of the file (Trappmg) and depending on the situation of imprinting or removal in the process of filing. Therefore, in the CTP process, spot color prepress processing is particularly important.

In general, the spot color ink is different in depth, and the size of trapping is different; spot colors and four-color colors are different, and trapping methods are different.

1. Dark color and light colors

Dark spot colors are connected to light colors, and light colors are Trapping to dark colors. Values ​​are generally between 0.02 and 0.15 mm.

2. Dark color and darker colors connect

When a dark spot color is connected to a darker four-color, it is generally recommended that the trapping process be performed from a small area to a large area.
(Trapping), the value is generally 0.05-0.15mm, in PackageEdge software, 0.05-0.15mm after Trapping is automatically imprinted. The same principle in CoreIDraw, but the processing method is different, more troublesome.

3. Spot color text

For colored text on spot colors, no matter how the colors match, Trapping should be done on the background to ensure the text shape. When the text is turned in CorelDraw, when the graphics is processed, the same color edge can be filled in the four-color layer according to the size of the word to achieve the effect of trapping.

CorelDraw and Photoshop for raster image processing spot color can be layered or multi-channel method, but in PackEdge, because it receives PS, EPS, TIFF, PDF format files, vector graphics and text can be directly Trapping, but the effect of the spot color of the image will change, Trapping is even more inconceivable, can only select the mask of each image to refill the spot color, for the effect of the image, such as blur, excessive, feather must be in PackEdge In the redo, its effect is even more natural than CorelDraw and Photoshop. The over-ladder is much smaller, and the color uniformity is the biggest advantage that PackEdge does excessively.