Color Desktop Publishing Technology Q&A (3)

1. What is ATM? ATM (Adobe Type Manager) is a font management system, which is a font rasterization management software developed by the Adobe company in the United States. It can expand Type 1 outline fonts into dot matrix data in computers and also used for terminal display and printer output. In addition, ATM also provides tools for users to create fonts themselves, and can add and develop Type 1 text and new fonts. Since the text data output by the computer is already a dot matrix type, even if the printer for text output is not a PS-compatible type, the PS word can be printed without a font library. However, text output is slower than printers with fonts. 2. What is a vector image? Vector images, also known as object-oriented images, are described by a set of numerical formulas. Its file format specifies how the digital company, its parameters, and its operations are performed. Since each part of the image is described by a corresponding numerical formula, the image content of each target can be adjusted simply by changing the parameters. Change the size (size). The operations such as angle (rotation) are only the modification of the parameters in the vector image, but for the bitmap image, it involves re-sampling and recalculating the complex process of each pixel of the entire picture. On the other hand, images obtained from electric extensions or scanners are always described directly in a lattice manner. If you describe it in a vector way, it will be complicated to the extent that it cannot be applied. Therefore, both of these image file formats have their scope of application and are commonly used image description methods for desktop publishing. 3. What is trapping control? In the production of color prints, where text, line drawings, and images are superimposed on one another, it is often the case that when these objects are superimposed on one another, they have differences in front and rear order, and the ones that lie in front will cover the back of the table. In technology, the front-facing object is called the foreground, and the object behind it is called the background; this front-to-back order is called the layer. If the foreground and the background have different colors, images with the same area and size appear on the respective color separation sheet or are hollowed out. In actual production, it is difficult to achieve very accurate results in the process of making and printing, so that the white or color overlap between objects in the printed matter will often appear, which will affect the final output image. With the perfection of the desktop technology, applying trapping control (also called trapping) at the overlap of various objects has become an essential function of the desktop system and is solved through software. Trap control technology is the use of computer software to solve the absolute overlap accuracy that is not easily obtained in the actual plate making process. The general principle of trapping is to use dark colors to define the outlines at the borders where there is no common color, and to create a fine border of common colors at the borders that have common colors. In color prepress software technology, trapping technology is a cross-product technology, and involves the cooperation of a variety of applications, the basis of which is the PS page language. 4. What is the trapping value based on? Trapping is controlled at the interface where the two colors intersect, the foreground (or background) shrinks or expands, and the hollowing or emptying process is called the trapping value. In order to avoid glazing at the overlap, the trapping value should be slightly larger than the four-color registration accuracy of the printing press. Due to the different printing processes used in various color prints, as well as the precision of paper and printing machinery, the more precise the printed matter, the higher the precision of registration and the lower the trapping value. The United States Printing Service and printing plants have published typical trapping values. For example: sheetfed offset printing, the use of copperplate paper dot line number is 150lpi, the trapping value is 0.08mm; newsprint web offset, the number of lines is 100lpi, the trapping value is 0.15mm. 5. Where is the difference between Choke and Spread? Shrinkage is the increase in the area of ​​the (light-colored) background, allowing it to intrude into the darker foreground (text or figure) on the boundary, while maintaining the shape of the foreground contour. The expansion is to increase the foreground area of ​​the lighter color, so that it will invade the background area with a darker color on the boundary, while maintaining the shape of the background outline. 6. What does Keep away mean? Let empty be when the background is black, and the foreground is hollowed out, when the CMY three shades need to be dealt with, so that the foreground contour is defined by the monochrome black version. 7. What is the difference between FM outlets and traditional halftone outlets? The traditional halftone dot copying process divides a continuous-tone original in a certain way. Each unit area has the same number of cells, and each cell is formed by a dot group, and the color tone is not continuous. It is called halftone. In a halftone image, the number of dots per inch is fixed, and the thickness or density of the original is reflected by the change in size or area of ​​the dots. Although the FM network technology also uses the principle of halftones to reproduce continuous originals, its dot size is fixed, and the density level of the screen is reproduced through dense or sparse dots, that is, according to the density of the various regions of the original. The probability of network reproduction is not the same. As a whole, there are no regular points in the network, so there is no problem with the point of view of the network, and since the production of the network points is controlled by the computer at random, every time the color separation scans, the reproduction probability of the screen in the same area in the graphic is different, so the four me The print can completely avoid the occurrence of moire. The dot type of the FM network is very small, so the copy effect is close to a continuously adjusted photographic image, and the image reproduction is of high definition, especially the fine level of the high-profile and dark-sounding parts are well reproduced. 8. What are the benefits of FM screening? 1) FM screening will not produce moire. Because the moiré is the result of periodic structural interactions, the dot distribution of the FM screening is irregular and there is no mesh angle, so the moire is not caused by the overlap of several color plates. 2) The resolution is good. In the AM screening technology, the definition is determined by the quality factor. The larger the quality factor, the smaller the area of ​​the output dot, the better the clarity. However, it is difficult to make the quality factor too large. Therefore, the screen area used for AM screening is particularly small, which is equivalent to the use of a considerable quality factor in the AM technology. Therefore, the definition is good, and no or little detail can be made when making the separation film. Levels of emphasis can also achieve better results. 3) FM screening is not sensitive to the difference in the code errors that appear in the platemaking process. Misalignment between versions has little effect on color and sharpness. 4) Low-resolution output devices using FM technology can also obtain high-quality images, while AM ​​technology must require high-resolution output devices. For example, using a 1200dpi imagesetter output FM image, the quality is significantly better than the quality of the 175-line AM image output from the 3000dpi imagesetter. 5) The dot distribution in the FM screening is irregular, so that as long as the dots in the FM screening are small enough, the printed matter can fully approach the original and achieve high fidelity. 6) High productivity. With the use of FM network dots, the scanning time can be reduced to 1/4, and the electronic file size can be reduced to 1/4, which greatly speeds up image editing, typesetting, and output operations, thus significantly improving the production of prepress systems. ability. 7) Support printing technology with more than four colors. It is not limited by the angle of the screen, and has a wide range of color reproduction, which can produce special high-fidelity printing effects that conventional four-color separation cannot achieve. 9. What is colour and device independence? Color and device independence is an important part of the standardization of image information exchange. The meaning is the result of the image color data obtained by a certain kind of image processing device, which should be able to be restored in another device. To achieve color independence from the device, it must first be possible to objectively evaluate the color and density of the image and the conversion characteristics between processing devices. This process can now be accomplished through a color management system. 10. What are the contents of color management? The content of color management mainly includes three aspects: correction, characterization and conversion. They are the three basic elements of color management and they are also three consecutive steps. Calibration is the basis of the other two steps and is the prerequisite for ensuring the normal operation of the system. The purpose of the calibration is to make all relevant equipment, such as scanners, monitors, printers, etc. meet the standard parameters of their factory specifications. The correction work does not guarantee that the image resembles the original, but whether each device meets the original design criteria. After the device is calibrated, it should be characterized. This characterization measure is what system and range the color of the input device and output device is after correction. Different devices have different color performance capabilities. The range of colors it can represent is not the same. Therefore, measuring the color gamut of an output or transmission device is the characterization of the device. The characterization measurement is to create a data file describing the color range of the device. This file is called a device profile. Conversion is the conversion of an image from the color space of one device to the color space of another device under known conditions. The purpose of the conversion is to match the colors and originals as much as possible on the screen and in the final printed matter. Since the color space of the print output device is smaller than the color space of the original, the color space should be compressed and converted. Color space conversions are RGB-CMYK (scanner to printer), RGB to RGB (scanner to screen), CMYK-CMYK (a printer to another printer).