Four-color printing and explanation of network points (on)

Why do we have to say about printing? It is not necessary to talk about how to do a good job in pre-printing after finishing the process.

Four-color printing:

As long as the R+G+B triads collide in proportion, more than 10 million colors can be generated. Why is it black? Yes, R. G. When the B ratio is equal, black can be produced, but if the three inks produce a color, it is not economical. In fact, in the design process, the use of black is very much, which is actually why four-color printing is used. Another point: After the RGB generated black is compared with the black obtained by direct ink mixing, the former has a sense of virtual float, while the latter feels more solid.

1. With the four-color principle everyone is much easier to accept. It is equivalent to the four films at the time of output. It is also equivalent to the four channels cyan, magenta, yellow, black (C, M, Y, K) in channels in PHOTOSHOP. The modification of the channel when we process the image is actually a change to the film.

2. Mesh outlets Net flat screen and hanging network.

Mesh: Each square inch, the number of outlets to be placed, 175 mesh for common prints, and 60 to 100 mesh for newspapers, depending on paper quality. Special printing has a special mesh, depending on the texture.

Outlets: sub-circular. oval. diamond. Square. Diamond shaped. FM network outlets. The figure above is composed of circular dots.

Net Angle: The angle between the line formed by the most closely connected dots and the horizontal line. Above is 45 degrees

Flat screen: The dots of the whole film are regularly distributed evenly and the same size, like a plane, without layering.

Hanging net: The dot size is not the same, and the net is layered.

What should I do before outputting film?

First, the format of the file

Most of the output centers now use the Square Grid Century RIP (pspnt) output system, and the HQ510, Israel's Sailing Angel, Heidelberg and other phototype output systems. All support postscrit printer description file. That is, the suffix is ​​called. Ps file.

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, 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.

(to be continued)