What is a film? How did the film come out of the printing house?

What is a film? How did the film come out of the printing house?

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When prepressing and making a plate, the original is divided into four colors: cyan (C), magenta (M), yellow (Y), and black (K). What is the color separation principle?

A: There are thousands of colors on the screen, such as color drawings or color photos. It is almost impossible to print this tens of thousands of colors in one color. The four-color printing method is used for printing. That is, the original is first color-decomposed and divided into four colors of cyan (C), magenta (M), yellow (Y), and black (K), and then the color is synthesized. The so-called "separation" is based on the principle of subtractive color method, which uses the red, green and blue color filters to selectively absorb light of different wavelengths, and decomposes the original into yellow, yellow and blue primary colors. In the color separation process, the color light absorbed by the color filter is the complementary color light of the color filter itself, so that on the photographic film, a negative film of the black and white image is formed, and then the screen is added to form a negative dot of the dot, and finally the color is copied and dried. Plate. This is the earliest principle of photographic color separation.

Due to the development of printing technology, we can now color, sample and convert the original color into digital information through prepress scanning equipment, that is, the original color is decomposed into red (R), green (G), and the same method as photolithography. Blue (B) three colors, and digitized, and then use the computer to mathematically decompose the digital information into four colors of c (C), magenta (M), yellow (Y), and black (K).

Why do prepress images need to be screened?

A: Because the printing process determines that the printing can only use the dot to reproduce the continuous tone of the original, if the picture is enlarged, it will be found that there are countless dots of different sizes. We see that the dot size is different, but they all occupy the same size spatial position. This is because after the original image is screened, the image is divided into a number of regularly arranged dots, that is, the continuous image information is turned into discrete dots. Image information. The larger the dot, the darker the color and the darker the layer; the smaller the dot, the lighter the color, and the brighter the layer. The size of the fixed space occupied by each dot is determined by the number of screen lines. For example, if the number of dots is 150 lpi, there are 150 dots in the length or width of one inch. The location of the dot space and the dot size are two different concepts. For example, C50% means that the dot size accounts for 50% of the dot space position, and 100% means that the dot size covers the dot space position, which is called "printing". In the field, 0% has no dots, only the dot space, so no ink is printed in this place. Obviously, the larger the number of nets, the smaller the space occupied by the dots, and the more layers that can be described, the more delicate. In fact, the level and color of the original are reproduced through this method of hanging nets.

What is the printing color?

A: The printing color is a color composed of different percentages of C, M, Y, and K, so it is more reasonable to call it a mixed color. C, M, Y, and K are the four primary colors used in printing. When printing the primary colors, these four colors have their own color version. The dots of the color are recorded on the color plate. These dots are generated by the halftone screen, and the four color plates are combined to form. The primary color defined. Adjusting the size and spacing of the color grid points will create other primary colors. In fact, the four printing colors on the paper are separate, but they are very close. Because our eyes have certain limitations in their resolution, they cannot be distinguished. The visual impression we get is the blending effect of the various colors, thus producing a variety of different primary colors.

Y, M, C can synthesize almost all colors, but also need black, because the black produced by Y, M, C is impure, requires more pure black when printing, and if Y, M, C are used to produce Black will have too much local ink problem.

What are the devices for the color desktop publishing system? What are the software?

Answer: The color desktop publishing system consists of three parts: graphic input part, graphic processing part and graphic output part. The specific components of each part are as follows:

(1) Graphic input section

Equipment: scanners, digital cameras, computers.

Software: Device driver software, and operating systems for MAC and PC.

(2) Graphic processing part

Equipment: Computer.

Software: 1. Computer software: Image processing software is Photoshop, Painter. 2. The graphics software is: FreeHand, CorelDraw. 3. The typesetting software is PageMaker, QuarkXpress. 3D image editing software: 3DS, Infihi-D, Strate-StudioPRO.

(3) Graphic output part

Equipment: computers, color printers, laser printers, laser imagesetters, direct platesetters, plate machines, etc., direct digital presses.

Software: RIP, driver software, font library.

What are the workflows for prepress or computer design?

A: The general workflow has the following basic processes:

1 Clear design and printing requirements, accept customer information

2 Design: including input text, images, ideas, imposition

3 black and white or color proofs, let customers modify

4 Modify according to the manuscript

5 Release the proof again and let the customer modify it until finalized.

6 Let the customer sign the film and then go out.

7 pre-press proofing

8 Send the proof to the customer, let the customer see if there is a problem, if there is no problem, let the customer sign. All work on the prepress design is completed. If there is a problem in the proof, you have to modify it and re-export the film.

What is the workflow for the computer design system to complete the design?

A: The workflow in the design system is as follows:

1 First, the original is scanned according to the final size of the image, and the image is adjusted in the image software, and some creative design work can be completed.

2 Typographic design work in graphics or typesetting software: including inputting text, drawing graphics, and placing images.

3 After the customer has finalized the document, send the file to the output center to output the film. The laser imagesetter works in the PostScript language. The RIP (Raster Image Processor) describes the layout as a bitmap image and is divided into C (cyan), M (magenta), Y (yellow), and K (black) colors. sheet. If the final requirement of the design is not the output film, but a large color inkjet sample, the output can be done with the inkjet printer.

How to choose the correct output corner?

A: In order to avoid hitting the net, in theory, the difference between the colors should be 22.5 degrees, but the practice shows that the four angles of 15 degrees, 45 degrees, 75 degrees and 90 degrees are very good, and the yellow version is visually stimulating. It is weak and has poor visual sensitivity. Therefore, it is generally set at 90 degrees. The vision is most sensitive to the 45 degree angle. Generally, the main color of the original is magenta or cyan is 45 degrees. For example, for the blue sky and white clouds, the blue version should be set to 45 degrees. For the morning glow and the sunset, the magenta version should be set to 45 degrees, and the magenta and blue non-45 degree angles can be set. For 15 degrees, the black version is set at 75 degrees.

After the file is output, only the black version has a corner, and the other versions have no corners. What should I do?

A: The only way is to re-output, and change the color of the corner from 100% BK to 100 00% M100% Y100% BK, that is, change the monochrome black to four-color black.

What should I do if the color version and the original color version are inaccurate?

A: Re-export all the color plates. Although this is the most stupid way, it is the safest way.

What is the image resolution? Why emphasize it?

A: The resolution of printed images has been introduced in the basic part of printing. We know that high-resolution images contain more pixels than the same-sized low-resolution images, and the image information is more and the details are clearer. One reason to determine the image resolution is to consider the output factor. Since images are used for different purposes, the resolution should be determined based on the purpose of the image. If an image is displayed on the screen, the resolution is 72Dpi or 96Dpi; if it is used for 600Dpi printer output, it needs 150Dpi image resolution; if printing, it needs 300Dpi high resolution. Row. The image resolution setting should be appropriate: if the resolution is too high, the running speed is slow, the disk space occupied is large, and the efficiency principle is not met; if the resolution is too low, the expression of the image details is not in accordance with the high quality principle.

Why do images need to have an image file format? There are several image file formats that are often involved in prepress. What is the nature of each?

A: The image file format determines what type of information should be stored in the file, how the file is compatible with various applications, and how the file exchanges data with other files. Since there are many formats for images, the format of the image should be determined according to the purpose of the image.

The image file formats commonly used in design are:

TIFF format: TIFF is a tagged image file for saving images composed of color channels. Its biggest advantage is that the image is not limited by the operating platform, and can be used regardless of PC, MAC or UNIX. It can store alpha channels and store color separation data in a single file.

EPS format: EPS format is used for printing and printing. It can store Duotone information, store Alpha channels, and store path and screen information.

GIF is an 8-bit format that can only express 256 colors. It is a common format for network propagation images.

PSD is mainly used as an intermediate transition of the image file to save the channel and layer of the image for later modification. The format is poorly versatile, and only Photoshop can use it, and few other applications support it.

JPE is both a file format and a compression method. This compression is lossy, and the loss is not the same. Some are too small to be discerned by the human eye.

What is the number of screens for printed images? What is the relationship between image resolution, scanning resolution, and laser imagesetter output resolution?

Answer: Since the printed matter is composed of dots, the number of screened lines in the printed image refers to the number of lines per inch of the printed matter in the horizontal or vertical direction, that is, the number of hanging nets. The number of screens is called because the earliest print dots are wired. The unit of the number of hanging lines is Line/Inch (LPI). For example, 150Lpi means that there are 150 network cables per inch. Adding a picture to the image, the larger the number of nets, the more the number of nets, the denser the nets, and the richer the level of expressiveness.

Because the computer image is a dot matrix, that is, one pixel (the smallest unit of the image is called a pixel). Image resolution can be visually understood as how many pixels are represented by a line in a unit length in the horizontal or vertical direction. The more pixels used to describe this line, the higher the resolution. The unit of image resolution is typically Pixels PerInch (pixels per inch), which is usually expressed in English as PPI. For example, if an image has a resolution of 300 PPI, it means that it has 300 pixels per inch in the horizontal or vertical direction; if the resolution of an image is 720I, it means that it has 72 pixels per inch in the horizontal or vertical direction.

Some devices have resolutions similar to those of images, except that they are expressed in dots, so they are represented as Dot Per Inch, or DPI for short. For example, an image scanner with a resolution of 1200 DPI has an image input accuracy of 1200 dots per inch, or pixels. The 3600DPI laser imagesetter has a graphic output accuracy of 3600 laser dots per inch.

The image resolution PPI and the printing resolution LPI (the number of screen lines) are related and different: the image resolution is higher than the printing resolution, generally 2 × 2 pixels generate 1 dot, that is, the LPI is DPI About one-half.

What is Pantone? Why use Pantone to set the color?

A: Pantone is a famous ink brand in the United States and has become a standard for printing colors. It has made all the inks produced by itself into chromatograms and color standards. Pantone's color code has become a recognized language for color communication. Users need a certain color and they can be calibrated according to color code. Due to the widespread use of the Pantone color code, the computer design software has a Pantone color library and uses it for color definition. When setting the color using the Pantone color library, the selection method is Pantone color, but it should be noted that most Pantone colors are spot colors. If you want to reproduce in four colors, you should set the color type to the primary color. Figure 1-13 is an interface that defines the Pantone color.

What is color separation? Is color separation so important? How to color separation in Photoshop?

A: Separation is a printing term that refers to the decomposition of various colors on the original into four primary colors: yellow, magenta, cyan, and black. In computer-printed design or graphic design image software, color separation works. It is to convert the color mode of the scanned image or other source image into CMYK mode.

Generally, the scanned image is in RGB mode, and the image taken with a digital camera is also in RGB mode. Most of the images downloaded from the Internet are in RGB color mode. If you want to print, you must divide the color into four colors: yellow, magenta, cyan, and black. This is the requirement for printing. If the image color mode is RGB or Lab, it is possible to output only the dot on the K version, that is, the RIP interpretation only interprets the color information of the image as gray.

In Photoshop, the color separation operation is actually very simple: just convert the image color mode from RGB mode or Lab mode to CMYK mode. The specific operation is to execute Image/Mode/CMYK. Thus the color of the image is represented by the colorant (ink), with a channel of 4 colors. When the image is output, the dots will be generated according to the color channel data, and divided into four color separation films of yellow, magenta, cyan and black.

In the case of color separation, when the image is transferred from RGB to CMYK, the naked eye can see that some colors on the screen will change significantly. What is the reason? What is the effect on the color of the image?

A: When the image is changed from RGB color mode to CMYK color mode, some bright colors on some images will change obviously. This change can be observed obviously, and it will change from vivid color to dim. Some colors. This is because the color gamut of RGB is larger than the color gamut of CMYK, which means that some colors that can be represented in RGB color mode are beyond the range of colors that CMYK can express after switching to CMYK. These colors can only be Replace with similar colors. Thus these colors produce a more pronounced change. In fact, if there is color in the RGB color mode image beyond the color gamut, you can use Gamut Warning to preview.

What is gamut space? What is the meaning of gamut space?

We edit images in RGB, CMYK, and Lab, the essential difference being working in different gamut spaces. The color gamut refers to the range of colors that can be expressed by a certain color mode. It also refers to the range of colors that can be expressed by specific media such as screen display, printer output, and print copy. The color of the visible spectrum in nature constitutes the largest gamut space, which contains all the colors that the human eye can see. In color mode, the Lab gamut has the largest space, and it contains all the colors in RGB and CMYK.

What mode is better for designing the color mode of the image?

A: In Photoshop, the image's color mode has RGB mode, CMYK mode, GrayScale mode and other color modes. Any mode for designing an image mode depends on the end use of the design image. If the designed image is to be printed or printed on printed paper, it is best to use the CMYK color mode so that the color seen on the screen is closer to the output print color or the printed color. If the design is for electronic media display (such as web page, computer projection, video, etc.), the color mode of the image is best to use RGB mode, because the color of RGB mode is more vivid and richer, and the picture is better. And there are only 3 channels of images, the amount of data is smaller, and the disk space is also small. If the image is gray, it is better to use the GrayScale mode, because even if the image is expressed in RGB or CMYK color mode, it still looks like a neutral gray color, but its disk space is much larger. In addition, if the gray image is to be printed, if it is expressed in CMYK mode, there are 4 editions in the film and printing. The cost is not big, and it may cause the color cast problem when the gray balance control is not good during printing. When the amount of ink is too large, the gray image will be colored.

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

A: In the design, customers often require gold and silver printing. Since gold and silver cannot be realized by four-color printing, their printing and technology have special requirements. When printing, gold and silver are processed according to the spot color, that is, printing with gold ink and silver ink, so the film should also be a spot color film, a film film alone, and print separately.

When designing a computer, you should define a color to represent gold and silver, and define the color type as a spot color to meet the design requirements. Since gold, silver and silver are opaque, gold and silver content can be set to Overpint when designing.

What is spot color and spot color printing? What is spot color and spot color printing?

A: Spot color means that when printing, instead of printing C, M, Y, K four colors to synthesize this color, it is specifically used to print the color with a specific ink. Spot color inks are pre-mixed by the printing house or produced by the ink factory. For each spot color of a print, there is a special color version corresponding to the print. Use spot colors to make colors more accurate. Although the color cannot be accurately represented on the computer, the pre-printed color sample card of the standard color matching system can see the exact color of the color on the paper. For example, the Pantone color matching system creates a very detailed color sample card. .

For the non-standard spot color set in the design, the printer does not necessarily accurately allocate it, and the exact color cannot be seen on the screen, so don't use your own defined spot color if it is not a special requirement.

What are the common color schemes used in computers? What is the best way to define colors in general?

A: A method is needed to describe different colors, whether on a computer or when printing. The color method is also called color model or color mode. There are many types of color models, each of which can describe colors from different angles, but different color modes are suitable for different occasions and the accuracy is different.

The computer color mode is:

1, RGB mode:

Also known as the RGB color space. It is a color scheme that is widely used in our lives, such as televisions, computer monitors, slides, etc., which use light to color. Scanning and publishing often requires scanning images. The first thing the scanner scans is the RGB color information on the original image. The RGB mode is an additive color mode, and any color can be described by the amount of radiation of R, G, and B. When the computer defines the color, the three components of R, G, and B have a value range of 0-255, 0 means no stimulation amount, and 255 means maximum stimulation amount. When R, G, and B are both 255, white light is synthesized, and when R, G, and B are both 0, black is formed. This mode is often used when displaying color definitions on the display. Images such as TV, slideshow, network, multimedia, generally use RGB mode.

2. CMYK mode:

Also known as the CMYK color space. CMYK is the most familiar to those in the printing industry. This mode is a subtractive mode that follows the subtractive color mixing rule. The CMYK mode essentially refers to the C, M, Y, and K dot sizes printed when the color is reproduced, so the values of C, M, Y, and K range from 0% to 100%. CO%MO%YO%KO% indicates white, C100%M100%Y100% K100% indicates black.

3, HSB mode: hue (HUE), saturation (Saturation), brightness (Brightness) mode.

Since the RGB image is better than the CMYK image display, the color is more beautiful, can you output the RGB image directly? What are the consequences of doing this?

A: Since the color gamut of RGB is larger than CMYK, some colors are displayed on the screen, but the four-color ink is not printed. If you want to know the consequences, just give it a try. Due to the difference of RIP, the RGB image may have only the black version on the color separation film, the other color version has no picture, or the information on the four color film (the dot) is exactly the same, that is, the equivalent gray image. Although some distribution software or RIP can convert RGB to CMYK, it is best to use scan software or Photoshop for mode conversion.

Save the color map as DCS format, there is a picture when printing black and white, but there is no picture on the output film. Why is that?

A: Saving the image as a DCS format will result in five files.

Why not set the resolution in typesetting and graphics software?

A: The typesetting graphics software is object-oriented software. The representation of text and graphics is expressed in the language of the algorithm. The objects produced are independent of resolution. They are output at the output of the output device. If the output device has a high resolution, the image output resolution of the created page is high. Therefore, graphics software and typesetting software do not need to set the resolution. The image imported in the typesetting and graphics software is required to read the dot matrix information of the original image when outputting, which is related to the resolution of the original image.

There are several types of text in CorelDraw?

A: CorelDraw divides the text into two different types, one is the art text and the other is the paragraph text. Although both texts are created using text tools, they have different characteristics, the art text. With more graphical object features, you can apply more special effects to the art text; while paragraph text can use more text formats. Based on the different characteristics of the two types of text, they can be used for different purposes. If you only need to use a small amount of text or apply more formatting to the text, such as a short title and description, you can use the word text; You need to process a large amount of text to apply more formatting, such as newspapers, brochures, etc., you can use paragraph text.