Prepress Output Problem Solution (I)

First, the file format Now most of the output center uses Square Grid Century RIP (pspnt) output system, and HQ510, Israel's Sailing Angel, Heidelberg phototype output system. All support postscrit printer description file. This is the file with the .ps extension.
Other common file formats that can be directly RIP output are: s2, s72, ps2 (Founder Edition), EPS, TIF, PDF, etc.
At present, the commonly used design software: photoshop, pagemaker, coredraw, illustrator, etc., can all generate a PS file or a PDF file through a postscrip virtual printer, and some Founder software such as Founder, Verizon, and Feiteng s2. The ps2, ps2, and ps files can also be output directly at the Founder Century RIP, but other output systems do not.
There are other word processing softwares such as word, wps2000, and so on, which can also generate PS files through postscript virtual printers. In fact, the prepress output must be processed such as imposition, registration line, cutting line, etc. However, word, wps2000 and other software can be said to be powerless in this regard, especially the color draft, once done, go to the later Processing will bring great difficulties. Therefore, try to use pagemaker and a series of professional design and layout software.
Second, the picture format, accuracy.
Modern offset printing uses offset printing (four-color overprinting), that is, the color picture is divided into four colors: blue (C), product (M), yellow (Y), black (B) four-color dot film, and then drying Into the PS version, after four offset printing presses, it is colored printed products.
The printing picture is different from the usual computer display picture. The picture must be in CMYK mode, but not in RGB mode or other modes. When the output is converted into pictures, which is the accuracy of pi, printing the image with the minimum theoretical accuracy to reach 300dpi / pixel / inch, and usually we often see the computer on the beautiful picture, on the monitor feel very beautiful, in fact, most Most of the 72dpi RGB mode pictures cannot be used for printing. The pictures used cannot be based on the display. Do not look at the picture because it is very fine with acdsee or other software. After zooming in, it is considered as a print. It must be opened with photoshop. Use a picture size to confirm its real value. Accuracy.
For example: If the resolution of an image is 600*600 dpi/pixel/inch, then its current size can be enlarged to more than double. If the resolution is 300*300dpi, then it can only be reduced or larger and cannot be enlarged. If the picture resolution is 72*72 dpi/pixel/inch, it must be reduced in size (dpi accuracy will be relatively large) until the resolution becomes 300*300 dpi. (When using this function, set "Redefine pixel" in the image size option in photoshop to none.)
Common picture formats are: TIF, JPG, PCD, PSD, PCX, EPS, GIF, BMP, etc. When making a draft, TIF color, black and white bitmap, EPS vector or JPG=
Third, the color of the picture On the printing of overprinting, overprinting, hollowing out, spot colors and other professional terms, we can refer to some of the relevant basic knowledge of printing, here only to say that some must pay attention to common sense.
1. Hollowing There is a row of blue words on the yellow floor. On the yellow version of the film, the location of the blue word must be empty. On the contrary, the blue version is also the same. Otherwise, the blue thing is directly printed on the yellow, and the color will change, and the original blue word will turn green.
2. Overprinting There is a line of black characters on a red base plate. Then on the red plate of the film, the position of the black characters should not be hollowed out.
Since black can suppress any color, if the black content is hollowed out, especially for some smaller characters, a slight error in printing will lead to white edges, and the contrast between black and white is relatively large and it is easy to see.
3, four-color black This is a more common problem. Before outputting, it is necessary to check the black text in the publication document, especially the small characters. It is not only on the blackboard, but it should not appear on other three-color editions. If this is the case, the quality of the printed product will be discounted. When the RGB graphics are converted to CMYK graphics, the black text will definitely change to four-color black. Unless otherwise specified, it must be processed before the film can be exported.

4, the picture is RGB mode RGB mode picture output, RIP system will automatically convert it to CMYK mode output. However, its color quality will be greatly reduced, and the printed products will be light in color and will not be bright. The effect is very poor. The picture is best converted to CMYK mode in photoshop. If it is a scanned manuscript, then it must go through the process of color correction and the picture can be used.
Fourth, the film hanging network accuracy.
Hanging net accuracy is generally referred to as hanging nets. The higher the precision of the netting, the finer the printed products, but it has a greater relationship with paper and ink. If you print on a regular newsprint (newspaper) a picture with a high mesh size, the picture will not only become more exquisite, but will become a mess (miserable). Therefore, you must understand the printing of your printed matter before exporting. What is the use of paper, and then determine the accuracy of the net.
General common paper and hanging mesh accuracy: imported coated paper or stickers, etc.: 175-200 lines imported offset paper, etc.: 150-175 lines of ordinary offset paper, etc.: 133-150 lines of newsprint: 100-120 lines to By analogy, the poorer the quality of the paper, the lower the hanging net, and vice versa.