Basic knowledge of film printing factory?

1. What is image resolution? Why emphasize it? (This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. For more details and business requirements of printing DM sheets, posters, picture books, brochures, handbags and envelopes, please visit [url]www.67902255.com or cqyinwu.com[/url]. )

A: A high-resolution image contains more pixels, more image information and clearer details than a low-resolution image of the same size, which is one reason for determining the image resolution by considering the output factors. For example, if you want to display an image on the screen, the resolution should be 72 pixels/inch. If it is used for printer output of 600Dpi, an image resolution of 150 pixels/inch is required; To print, you need a high resolution of 300 pixels/inch. The image resolution should be set properly: if the resolution is too high, it will run slowly and occupy a lot of disk space; If the resolution is too low, it will affect the performance of image details and fail to meet the corresponding quality requirements. (This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

2. Why do images need image file format? Several image file formats are often involved in prepress. What are their properties? (This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

A: The image file format determines how the file is compatible with various application software and how the file exchanges data with other files. Because there are many image formats, we should decide which format the image should be stored in according to its use. (This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

The image file formats commonly used in design are:

TIFF format: TIFF is a marked image file used to store images composed of color channels. Its biggest advantage is that the image is not limited by the operating platform, and can be used in PC, MAC or UNIX. It can store Alpha channel and color separation data in one file, and it is the most commonly used image format for printing files.

EPS format: EPS format is used for printing and printing, and can store the information of two tones, Alpha channel, path and screening.

GIF is an 8-bit format and can only express 256 colors. This is a common format for transmitting images on the network, and it can't be used for printing.

PSD is mainly used as the intermediate transition of the image file, which is used to save the channels and layers of the image for later modification. This format is not universal, only Photoshop can be used, and other applications rarely support it, so it can't be directly used for printout.

JPE is not only a file format, but also a compression method. This kind of compression is lossy, with different losses, some of which are too small for human eyes to distinguish and cannot be directly used for printout.

(This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

3. What is printing color?

A: The printing color is composed of different percentages of C (cyan), M (magenta), Y (yellow) and K (black), so it is more reasonable to call it mixed color. C, M, Y and K are four primary colors commonly used in printing. When printing, these four colors have their own swatches, and the dots of this color are recorded on the swatches. When four swatches are combined, the defined primary colors are formed. In fact, the dots of the four printing colors on the paper are separated, but the distance is very close. Because of the limited resolution of our eyes, we can't distinguish them. The visual impression we get is the mixed effect of various colors, so different primary colors are produced.

Y, M and C can synthesize almost all colors, but black is needed, because the black produced by Y, M and C is impure, and more pure black is needed for printing.

Electronic files used for printing must be four-color files (that is, C, M, Y, K), and files in RGB color mode cannot be used for printout. Remember! !

4. What is color separation? Is color separation that important? How to separate colors in Photoshop?

A: Color separation is a printing technical term, which refers to the decomposition of various colors on the manuscript into four primary colors: yellow, magenta, cyan and black. In computer printing design or graphic design image software, color separation is to convert the color mode of scanned images or images from other sources into CMYK mode.

Generally, the scanned images are in RGB mode, and the images taken by digital cameras are also in RGB mode. Most of the pictures downloaded from the Internet are in RGB color mode. If you want to print, you must separate colors into yellow, magenta, cyan and black, which is the requirement of printing. If the color mode of the image is RGB or Lab, it is possible that only K version has dots when outputting, that is, RIP only interprets the color information of the image as gray.

In Photoshop, the color separation operation is actually very simple: just change the image color mode from RGB mode or Lab mode to CMYK mode. In this way, the color of the image is represented by pigment (ink), and there are four color channels. When the image is output to the film, it will generate dots according to the channel data of colors and be divided into four kinds of dichroic films: yellow, magenta, cyan and black.

(This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

5. In color separation, when the image changes from RGB to CMYK, the naked eye can see that some colors on the screen will change obviously. What is the reason? What effect does it have on image color?

A: When the image is converted from RGB color mode to CMYK color mode, some bright colors on the image will change obviously. This change can sometimes be clearly observed, and generally changes from bright color to darker color. This is because the color gamut of RGB is larger than that of CMYK, that is to say, some colors that can be expressed in RGB color mode are beyond the range of colors that can be expressed in CMYK after being converted into CMYK, and these colors can only be replaced by similar colors. So these colors have changed obviously. When making electronic documents for printing, it is suggested that the initial file should be set to CMYK mode to avoid using RGB color mode and avoid color difference during color separation conversion.

6. What color mode is better for designing images?

A: In Photoshop, the color modes of images are RGB mode, CMYK mode, gray mode and other color modes. What mode is adopted in the design image mode depends on the ultimate goal of the design image. If you want to print or print the designed image, it is best to use the CMYK color mode, so that the color you see on the screen is close to the output printing color or printing color. If the image is gray, it's best to use gray mode, because even if the image is represented by CMYK color mode, it still looks neutral gray, but its disk space is much larger. In addition, if you want to print a gray image, if it is represented by CMYK mode, there are four versions when the film is made and printed, and poor gray balance control during printing may cause color cast. When the amount of ink in one color is too large, the gray image will have color cast. If it is designed for electronic media display (such as web page, computer projection, video recording, etc. ), it is best to use RGB mode because the color mode of the image is brighter and richer, and the picture is better. Moreover, the image has only three channels, so the data volume is smaller and the disk space is less.

(This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.67902255.com[/url]. )

7. What are spot color and spot color printing?

A: Spot color means that when printing, this color is not printed with C, M, Y and K, but printed with a specific ink. Spot color ink is pre-adjusted by printing factory or produced by ink factory. For each spot color of printed matter, there is a special color plate corresponding to it when printing. Using spot colors can make colors more accurate. Although the color can't be accurately expressed on the computer, you can see the accurate color of the color on the paper through the pre-printed color swatch card of the standard color matching system such as Pantone color matching system, thus creating a very detailed color swatch card.

For the non-standard spot colors set in the design, the printing factory may not allocate them accurately, and the accurate colors are invisible on the screen, so if it is not a special demand, don't use your own defined spot colors easily.

8. How are gold and silver printed? What are the requirements for prepress design?

A: In design, customers often require gold and silver printing. Because gold and silver can't be achieved by four-color printing, their printing and technology have special requirements. When printing, gold and silver are treated as spot colors, that is, gold ink and silver ink are used for printing, so the film should also be spot color film, and a separate film piece should be printed separately.

In computer design, we should define a color to represent gold or silver, and define its color type as spot color to meet the design requirements. Because gold, silver and silver are opaque, gold and silver can be set as Overpint when designing.

(This information is collected and provided by Chongqing Dongting Printing Graphic Design Co., Ltd. [url]www.cqyinwu.com[/url].)

9. What is bleeding? Why are you bleeding?

Any image beyond the cutting line must have a certain margin (usually 3mm) outside the cutting line, so as to allow a small amount of dislocation during trimming and cutting. This edge is called bleeding.

10, what is the printing process?

Prepress work generally refers to photography, design, production, typesetting, film production, etc.

In the middle stage of printing, the finished product is printed by the printing machine.

Film (film) cannot be directly used for printing. The color plate for printing is usually called PS plate, which is an aluminum metal plate, and one side of the color plate is covered with a medicine film. The function of the film is to fix the medicine film on the color plate during exposure. The specific operation is as follows: the side of the color plate covered with the medicine film is covered with film, and exposed under purple light. Where the film is completely transparent, the color plate will be completely irradiated by purple light, and the drug film will be completely decomposed. Where there are images or characters on the film, the film on the color board will not decompose or completely decompose, and the decomposed film will be washed away, so that the image on the film will be completely transferred to the color board.

When printing, the ink will be absorbed in the place where there is a medicine film on the color plate. With the different density of the film, the amount of ink adsorbed is also different, so there is a difference in color depth.

Paper is colored by four color plates C, M, Y and K in the printing machine, and various colors come out.

Post-press work generally refers to the post-processing of printed matter, including cutting, pasting, die-cutting, binding, mounting and so on. , mostly used for publicity and packaging printed matter.

1 1. What font should I use when making electronic documents for printing?

If the file is typeset by illustrorar or CorelDraw, there will be no font problem. Because all the text in the file will eventually be converted into a vector diagram (that is, to create an outline), and it must be converted into a vector diagram, otherwise the text will be misplaced when output.

However, because the word processing functions of illustrorar and CorelDraw are not strong, we may use pagemaker more for the convenience of typesetting, which involves the trouble of fonts.

Pagemaker must use professional printing fonts when typesetting the Chinese version, otherwise the file may not be output normally. 04 font in English font can't be output normally, please don't use it.

There are many kinds of printing fonts, such as Hanyi, Fangzheng and Wen Ding. According to my experience, Hanyi font is the best. Founder and Wen Ding are not stable enough, which may cause problems.