Pre-press technology case solution (9)

Questions about paper size

A: Generally, the common sheet of paper is called No. 0 paper. The paper is divided into large and positive degrees. The so-called opening number is the number of equal parts of the No. 0 paper. For example, the 16 equal parts are 16K. Taking the degree 16 as an example, the net size is 210mm×285mm, and the bleeding edge (each 3mm on each side) needs to be set in the PS, that is, the actual image size is 216mm×291mm. The simplest way of other normal opening numbers is to multiply the length and width of 16K by the corresponding multiple, for example 4K is the multiplication of 2 on each side. That is 210mmX2 = 420mm, 285mmX2 = 570mm (net size), and then add the width of the bleeding edge on it. It should be noted that the above is the most basic method of opening. There are many ways to open paper. There is no one to describe here. You can browse the corresponding printing websites by yourself to understand the different methods of opening and opening the paper.
Set correct resolution

A: Make sure your photos, scanned images, and other bitmaps have the appropriate resolution. This is necessary to ensure the quality of the output file (the resolution is not related to the Postscript vector, they will print at the output device's maximum resolution) . The following are some of the standard output format resolutions.

At 72dpi, when you scale an image for a webpage, it is best to ignore the Print Size section of Photoshop's Resize Image dialog box, as long as you work with pixels.

Newspapers have a scanning resolution of 125-170 dpi. For printed images, the resolution is set to 1.5 to 2 times the network cable (lpi). (2x will make the image more flexible when zoomed in). 85lpi for newspaper printing.

The magazine/propaganda product uses a scanning resolution of 300 dpi because the magazine is printed with 133 or 150 lpi.
High-quality books use a scan resolution of 350-400 dpi because most print-ready books use 175 to 200 lpi.

Wide-format printing uses a scanning resolution of 75-150 dpi. For large-format images (such as posters) viewed from afar, low resolution is acceptable, and the low scale mainly depends on the viewing distance: the menu after the cashier is better than The banner hanging from the roof has a higher resolution.

How to use the fastest way to output?

Use ai to do more pages of the book, a total of 200 files saved as eps format, and then imported into the pm into 4 open output, do ps file found half an hour to print a set, the speed is too slow, solution :
1. Save the file in AI as AI7.0 format.
2. Import the AI ​​file in CD9 for printing (it is recommended to have the best effect under the 2000 platform).
Overprinting, overprinting, trapping, embossing?
Overprinting: refers to the overlapping registration of multi-color printing when the various color printing patterns are required;
Trapping: refers to a color block and another color block convergence should have a certain overlap and overlap, in order to avoid the printing of white edges, it is also called dew white; two color transfer place may not be in the trapping time There is a shift in the printing, resulting in white edges or aliasing. The trapping is to infiltrate the two points of the transfer at the point of transfer, and no white edges will be produced.

Embossing and overprinting mean one color patch over another. However, when printing, special attention should be paid to the overprinting of the black text on the color image. Do not hollow out the pattern under the black text. Otherwise, the black text will show white edges.

Example: Four P's grandnesses of 16 open, made with PS, texts with K100, sent to the film center to tell the black characters are not imprinted, that is, the position of the black characters is hollow on other color plates, will result in overprinting Inaccurate and revealing, the overprinting of the black text in PS is to change the layer mode of the black text layer to a multiplicity, so that in other color versions, the black characters are not hollowed out, and thus, there will be no white appearance. The situation has just entered the printing industry and like to use PS design friends must pay attention to this issue. Do not, we must develop PS to do the bottom map, CD or AI typing good habits. There will be no glitches on printed text.

Black in general CD and PM are default embossing.

1. Are all bitmaps trapped or trapped? Because some customers directly gave us a bitmap (some bitmaps are quite complex) files, output proofing, did not find any unacceptable phenomenon.
A: Unusual ~~~ overprinting can be as long as K100's black or graphics

2. How thick should the lines be overprinted to register the color and print? A trace (0.01 mm) enough? How much does it turn into pt units?
A: The very thin line ~~ is 0.2 points. 1pt=0.35146mm

3. Do overprinting in CD and ILL. Are they all the same in principle? It seems that the thickness of the overprint in the ILL line is half of the line, is it not? What's on the CD?
A: No such statement.
4. Is it safer than CD to do overprinting in ILL?
A: Do it in the normal way. Software is just a tool, with no good or safer points

5 spot color overprint, spot color and black, specifically, black, is not overprinted with lines? Spot color and black, special, black, is not using padding? If you want to prevent the appearance of "black and black" patterns, can you just overprint them? Or what other method? Or do you need to overprint possible color registrations? Is the spot color a transparent attribute? That spot color can't be overprinted with spot colors, can only be overprinted with lines?
A: Relatively speaking, the lines are overprinted better.

6. Suppose some kind of overprinting assumption is in ILL, a pattern, the middle is filled with red, green contour lines, under the green filled pattern, can do line overprint (with the outline of the same green with red lines, with the bottom of the green Fill, make overprint)?
Answer: No need to do overprinting. Normal output can

7. If it's just CMYK, the pattern is similar to the color insert in "The Cartoon King", or the cartoon in "Cat and Mouse". The animated characters have black lines and are used to indicate their outlines. Do you have to do overprinting with such a complicated figure? It is difficult to imagine a color block, a color block for overprinting? ! If you do not make overprints, how do you print those anime magazines?
A: Again, under normal circumstances only black overprint, other colors normal output.

8. If the black outline on the artwork given to me is made by the method of “leaking black” (for example, a strip of red, green, and black under the seam), is this artwork not? "Can only hook it over again, then make overprinting," is not too sad A: The following is a piece of black to do overprinting can actually superimpose the printing is very simple, remember one can: under normal circumstances only the black word or Black graphics do overprint processing, other colors default normal output ~
If it is a multi-million-dollar printing vehicle like Heidelberg, there will be no overprinting problem at all. However, according to the national conditions of the country, many printers do not have such good equipment. Therefore, there is an inaccurate printing press and overprinting. phenomenon.

When stacking strokes, it is generally based on experience. A large area of ​​strokes should be set thicker.
0.1~0.2mm is suitable, and small area filling strokes should be relatively fine. After the strokes are folded, use a magnifying glass to observe the prints. Sometimes you will find that the strokes are dark. There is no way.

Why is the four-color black not the K100?

A: In Photoshop, the setting of four-color black is very special. As far as Photoshop 7.0 is concerned, the default black mark of the software is always: C75 M68 Y67 K90. This is a really unreadable figure-- Recently, some people have asked this question. Because of this, we welcome this discussion.

In fact, the default black in the software, Photoshop is the initial setting for the LAB mode, the value is L0 a0 b0, which is the calculated value in the software system, and the color of R0 G0 B0 of RGB color is exactly the same as L0 a0 b0. , so this color is also accurate "black" color.

However, interesting things happen in CMYK colors: in CMYK colors, K100, which is usually called single black, cannot accurately express this "system black", and has a larger RGB (Lab) color than CMYK color systems. In the department, the K100 is just incomplete dark gray, and this dark gray is reddish tone! - It's no surprise that this is true in the printing factory. The printing masters use black expensive ink, and the effect printed is far less than the black in the RGB color. Still reddish tone. With regard to reddishness, we can look at the "grey" parts of a large number of prints - careful, long observations will reveal that they are all impure gray red.

Now we can easily understand why there is this puzzling figure in Photoshop: C75 M68 Y67 K90. Now that the single black is not black enough, it will add more pigment. It turns out that when CMY and K share, it can be more Full black effect, but also to correct that unpleasant "reddish tone", CMYK color plus about 8 percentage points of the blue (C) ink balance, which is a simple and effective method.

If you are interested, we can also discuss in more depth the black (K) ink color cast:

When the black ink (with a white printing ink) is washed very lightly (note that it is not minus the net), the single black (K) ink is a bluish tone, but as the dilute is weakened, the color cast will slowly bias toward the blue-violet Blue-violet-purple-red.

Why can't we see blue in print? We can use a magnifying glass to look at the grayscale in prints. In fact, they are not produced with white printing inks. Instead, they are printed with 100% black ink through net reduction, so they all show the deepest The color cast: red tone.

The last two points to add are:
Because all single black gray colors are strictly reddish, so in Photoshop, you want to get the ideal gray color, it is best to add a certain proportion of blue (C) color;

For text, we all know that multi-channel black is easy to print and paste, so when designing (printed) text in Photoshop (especially the small print), we must use 100% single black.

If there is a gray block, it will be sent to the film company and there will be dots in the gray strip. The file is K20, and the dots on the display cannot be seen. The depth of the color is probably controlled by the density of the dots. The screen shows a color block, but the printing is based on dot. If you look at it with a magnifying glass, the color of each dot is actually a solid color, but their distribution is dense. How can we make ugly gray, it is recommended to use non-gradient spot colors.

Four-color print printing to do white version?

There is a situation where, for example, printing on the Yellow Pages phone book requires printing a set of white (a white color patch) containing the area to be printed and then printing four colors, of course, on other colored materials. Printing, but do not want to fold four colors, also need to print white.

If you only have white areas on the printed area, how do you design white plates? Four-color printing can be used to separate out the channel, out of the white version to do it, if the printed body is solid, the white version to paint it? Is there an easy way?

Create a black version of the same area as the printed one. Mark it as a spot color white. Print first and then print white and print four colors. The white version is actually a spot color version with the same area as the one you need, CMYK+ spot color white. For example, if you want to write on a cement wall, you usually need to apply a layer of white paint first, and then use other colors. The reason is the same.