Four-color printing and network basic theoretical knowledge introduction (below)

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, that is the precision: dpi, the printing image with a minimum theoretical accuracy to reach 300dpi / pixel / inch, and usually everybody often see the beautiful pictures on the computer, on the monitor feel very beautiful, in fact Most are 72dpi RGB mode pictures, most of which 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 image 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 compression bitmap is commonly used before printing output software The graphics format, pictures try to use these three formats.

Third, the color of the picture

With regard to some technical terms such as overprinting, overprinting, hollowing out, and spot colors on printing, we can refer to some of the relevant printing basic knowledge. Here only some common sense that must be noted.

1, empty

There is a blue line on the yellow bottom plate, then the blue word on the yellow plate of the film 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, overprint

There is a line of black on a red base plate, and 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

When the RGB mode picture is output, the 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.

Before printing, you must pay attention to the following issues:

1, when the production of more commonly used design and production software, such as pagemaker, etc., like the word as much as possible.

2. The mode of the picture in the text must be CMYK mode, with a minimum accuracy of 300*300 dpi/pixel/inch.

3. Check if the text in the publication is a four-color word. If it is, change it to monochrome 100% black.

4. If pagemaker, WS, Founder, and Illustrator are used, the linked image file must be copied along with the original file.

5, photoshop file is best psd (unmerged layer) file, in order to facilitate the modification.

6, the font as much as possible using common fonts, such as Founder, Wen Ding. Try not to use rare fonts. If used, coreldraw and Illustrator first convert the text to outline, which avoids the problem that the output center cannot output without such a font. If you have a make-up file, you must copy the make-up file.

7, clearly told the output center print product size, print volume, printing paper, etc., to facilitate the imposition and hanging net.

8, if the two pages are the same, but the black text is different (frequently encountered), then only the first page of the CMYK four-color, and the second page of the K-color can be, so as not to waste, but also save money. If there are only two colors (such as red and black) and the printing requirement is not high, it is only necessary to output it in one color version at the same time, and it is not necessary to divide the output into two colors. Deal with the printing plate. It also saves money.

Network point of view

Blue: 15 degrees red: 75 degrees yellow: 90 degrees black: 45 degrees

The layout of the general network is neat, so there will be an angle in the application. For example, in the case of monochrome printing, the angle of the screen is mostly 45 degrees. This is based on the dots printed on this point of view, and is most comfortable for the eyesight. And it is not easy to notice the presence of outlets, which results in continuous graying. As for printing with two or more colors, it is necessary to pay attention to the combination of the angles of the two nets, otherwise an unnecessary pattern will be created, which is called "Moier". Usually the difference between the angles of the two nets is 30 degrees, no net collision will occur, so the general two-color printing, the main color or dark color with 45 degrees, light color with 75 degrees, three colors are respectively 45 degrees, 75 degrees, 15 Degrees and other three angles, if it is the four-color printing, they are red with 75 degrees, yellow 90 degrees, green 15 degrees and black 45 degrees. There is no certain limit to these angles. They are changed according to different needs.