Pre-press picture preparation precautions
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Most of the current output centers use the square-scale grid (pspnt) dot-segment color separation output system, and some systems using Harry Kun or Israel's match angels. But it all has one thing in common, supporting postscrit printer description files. This is the file with the suffix .ps.
Currently more popular design software: photoshop, pagemaker, coreldraw, illustrator, etc. all support PS printing. The s2, ps2, and ps files generated by some Founder software such as Founder, Weiss, and Feiteng can only be output with pspnt, and other output systems do not. Others have some word processing software like word, wps2000, etc. In theory, ps files can also be generated, and the film can be output, but in fact, the prepress output must be processed such as imposition, add-on alignment lines, and cutting lines. And word, wps2000 and other software can be said to be powerless in this respect, especially the color draft, once done, and then go to post-processing, it will bring great difficulties to the pre-press output staff. Therefore, try to use a series of professional design and layout software such as pagemaker.
First, about the format and accuracy of the picture
Modern offset printing uses offset printing (four-color overprinting), which is to divide the picture into four colors: blue (C), product (M), yellow (Y), black (K) four-color dot film, and then sun The PS version, after four printings by the offset printing machine, is a color printed product. Therefore, the picture for printing is different from the picture for normal computer display, and the picture must be converted to CMYK mode, and RGB mode or other modes cannot be used. Because the output is to convert the image into dots, that is, the precision pi, the theoretical precision of the printing image is 300dpi/pixel/inch. Therefore, the pictures used by ordinary people cannot be displayed. Do not pass the image through acdsee or other. The software is very beautiful. It is also very beautiful after zooming in. It can be used as printing. It must be opened by photoshop, and the image size is used to confirm its true precision. For example, if a picture resolution is 600×600dpi/pixel/inch, then its current size can be enlarged to more than doubled. If the resolution is 300 × 300dpi, then it can only be reduced or enlarged, and can no longer be enlarged. If the image resolution is 72 × 72 dpi / pixel / inch, then it must be reduced in size (dpi accuracy will become relatively large), until the resolution becomes 300 × 300dpi, can be used. (When using this function, the "Redefinition Pixels" item in the image size option in photoshop is set to none.)
Second, the color of the picture
For some technical terms such as overprinting, overprinting, hollowing out, and spot color on printing, you can check out some related printing basics, which I will not explain here. Just say some common sense that must be paid attention to.
The first is the hollowing out problem. For example, if a red board is pressed with a blue line, then in the red version of the film, the position of the blue word must be empty. The same is true for the blue version.
The second is the overprint problem. For example, if a red board is pressed with a black line, then the position of the black word should not be hollowed out on the red version of the film.
The third is the problem of four-color words. This is also a more common problem. Before the output, you must check the black words in the publication file, especially the small characters, whether it is only on the blackboard, but not on the other three-color version. If it is as it is, the quality of the printed product will be discounted. When the RGB graphics are converted to CMYK graphics, the black text will become four-color black. It must be processed before the film can be output. 4. About the accuracy of the hanging network when outputting. The accuracy of hanging net is generally called hanging net. The higher the precision of hanging net, the more exquisite the printed product is, but it has a great relationship with paper and ink.
If you print a picture with a high net on the general newsprint, then the picture will not become more beautiful, but will become a mess, so you must know what the printed paper of your print is before exporting. Then decide the accuracy of the hanging network. Common common paper and hanging mesh accuracy: imported coated paper or stickers, etc.: 175 ~ 200 line imported offset paper, etc.: 150 ~ 175 line ordinary offset paper, etc.: 133 ~ 150 line news paper: 100 ~ 120 lines, to In this way, the worse the paper quality, the lower the hanging net and vice versa. To sum up, the issues that must be noted before the prepress output are:
1. Use the more commonly used design and production software, such as pagemaker, etc., like Word, try not to use it.
2. The mode of the picture in the text must be CMYK mode with a minimum precision of 300 × 300 dpi / pixel / inch.
3. Check if the text in the publication is a four-color word, and if so, change it to monochrome 100% black.
4. If you use pagemaker, Weiss, Founder Edition, Illustrator, you must copy the link image file and the original file.
5. The photoshop file is preferably a psd (uncombined layer) file for easy modification.
6. Fonts are best used in common fonts, such as Founder and Wending. Try not to use rare fonts. If used, coreldraw and Illustrator first convert the text to an outline, which avoids the problem that the output center cannot be output without such a font. If there is a supplementary word file, the supplementary word file must be copied together.
7. Clearly report the finished product size, printing volume, printing paper, etc. of the printed output of the center to facilitate imposition and hanging.
8. If the two pages are the same, but the black text is different (often encountered), then you only need to output the CMYK four colors of the first page, and the K color of the second page, so as to avoid waste and save money. If there are only two colors (such as red and black) and the printing requirements are not high, just output them in one color version at the same time, and do not need to be divided into two color outputs. Just deal with it when printing and plate making. Also save money. Third, 12 items of output preparation points
1. Set the file so that the page size of the layout file matches the page size of the printed matter, allowing the application software to automatically generate the correct positioning cut line. Using numbers - There are now two ways to determine the size and position of page elements in each typesetting software. One method is to tap the perceptual method of dragging the mouse, and the other is an objective method of entering numbers from various dialogs and control panels. To make sure that the width of a box is exactly one and a half inches, the only correct way is to type 1.5 in the width bar instead of using the eye or aligning the reference line and size.
2. Unless the font is very complicated or the details are fine, convert any text in the EPS file to a path before you enter the image into the typesetting software. Use good fonts - many output centers don't want to see TrueType words, and PostSript has become a standard.
TrueType usually has the same word name as the corresponding PostSript word, causing a conflict. TrueType must be manually downloaded to the RIP of the imagesetter. This is a very time consuming task, contact the output center in advance. Do not use the font command to produce a bold or italic effect. It is best to select the desired font effect directly from the application font menu. If the font does not have the desired coarse or oblique effect, and the font command is used, the MAC will forge a bold or italic effect for each word, but this is only on the screen.
If it is output on the printer, the final print effect will look like it has not been used at all. So what is the effect of using the bottom line? Don't use the fonts that don't have the effect of the font itself. If you are using a beautiful serif or fine stroke font (Bodoni is a good example), and the size of the word is set small, do not divide the word. Otherwise, even if the plate is aligned with a slight misalignment, the overprinting of the most sensitive part will be inaccurate.
3. Scan or capture the image as much as possible with the final output size and the appropriate resolution (larger is not necessarily good).
4. Rotate, mirror or invert the image in the software that created the image, not in the typesetting software.
5. Remove extra paths and channels to simplify the file before storing the final picture.
6. If the image is to be color separated, use CMYK mode to define the color. If it is not output, it is defined as a spot color.
7. Store pictures in uncompressed TIFF or EPS format.