Printing image information processing of the hotte

Color desktop publishing system printing image information processing

color desktop publishing system

color desktop publishing system, also known as DTP, is the abbreviation of desk top publishing, which gets its name because it is small and can be placed on the desktop

color desktop publishing system is a new prepress processing equipment launched in the 1990s, which is composed of desktop color separation and desktop electronic publishing. It solves the defect that the electronic color separation machine has a weak function of processing characters and cannot make negative or scientific negatives with the integration of text and text

the color desktop is often equipped with a splitter board (sleeve) publishing system, which is divided into three parts: output, processing and output

first, the input device of DTP

the basic function of the input device is to scan, separate colors and input the original into the system. Except that the text input is the same as the computer typesetting system, the image input can use a variety of devices, such as scanners, electronic color separators, cameras, plotters, and satellite ground receiving stations. Scanners are often used

there are two types of scanners: platform type and roller type. The scanner used in the color desktop publishing system should have the input resolution, color digits and scanning density range suitable for the printing requirements

(I) input resolution

refers to the number of points sampled per inch, expressed in dpi. DPI has the following relationship with the number of dots and lines LPI:

dpi (input resolution) = number of dots and lines × Zoom rate × Coefficient

the coefficient is generally 1 ~ 2. As the magnification increases, the required resolution increases. The magnification of the reflected original is small, which is 1500dpi based on 5 times. The format of the transmission original is small. If it is 10 times, 3000dpi is OK. Some scanners have a resolution of 6000-8000dpi. The resolution actually used depends on the output resolution and the zoom ratio of the image

(II) color bits and scanning density range

color bits refer to the number of binary bits used to represent a certain color, such as 8 bits, 16 bits, 24 bits, 36 bits, etc. The scanning density range refers to the density difference between the brightest and darkest places. Generally, the larger the scanning density range, the more color bits. If the density range is greater than 3.0, at least 10 bits are required

in addition, the scanner is required to provide a standard general data format, accurately and reliably accept the control of the workstation, have the function of automatic environmental correction, and be able to compensate for the interference of external light. At the same time, on the premise of ensuring that the main technical indicators of the scanner are met, the faster the scanning speed is, the better

II. DTP processing equipment

processing equipment is collectively referred to as graphic workstation. The basic function is to process the original that enters the system. 2) if the distance from the fracture to the nearest gauge end line is less than 1/3l0, the data is processed, such as color correction, revision, composition and creative production, plus words, symbols, etc., to form a complete picture and text integrated page, and then transmitted to the output device

at present, the computers used are apple cameras (MAC)? PC and workstation, etc. Due to the extremely rich hardware and software available for desktop systems, when selecting hardware and software suitable for printing requirements to combine into a system, we should consider several issues, such as processing speed, processing capacity, system network, Chinese environment and so on

(1) processing speed

image processing requires that the points in the image be processed point by point, with a large amount of data and high speed. A high-grade microcomputer or workstation should be used

(2) processing capacity

image processing requires higher and higher input resolution and output resolution, so the capacity of workstation to process data is required to be larger and larger. At the same time, it is also required to store a large number of ready-made picture libraries and word libraries

(3) system network

if the work of the color desktop publishing system works together, multiple computers complete a task together, and people can also enjoy the expensive scanning and recording equipment that makes the sample slip during the experimental process. Therefore, it is necessary to select a reasonable system network, network server and file server to support

(4) Chinese environment

the development of various application software abroad is very rapid, and it is impossible to translate the new application software into Chinese and then use it in China. This requires that the workstation has a good Chinese environment and good compatible and open performance. It can transplant the new western software directly to the Chinese environment of the system without any problems

third, the output device of DTP

the output device is the device for the color desktop publishing system to generate the final product. It is mainly composed of high-precision laser Imagesetter (also known as graphic recorder) and rip (raster image processor). The laser Phototypesetter uses the laser to gather the light beam into light spots, hit the photosensitive material to make it photosensitive, and become a black-and-white negative after development. Rip accepts the layout of postscript language, converts it into raster images, and then outputs them from the imagesetter. (postscript is a page description language developed by Adobe, which is now accepted by many people and has become a standard.) Rip can be implemented by hardware or software. The hardware Rip is composed of a high-performance computer and a special chip. The software Rip is composed of a high-performance general-purpose microcomputer and corresponding software. In order to meet the requirements of printing for image processing, we must consider the output resolution, output repetition accuracy, output plus structure, output speed and other performance indicators of laser Imagesetter and rip

(1) output resolution

the text resolution is generally 700 ~ 900dpi, the image resolution is 60 lines/cm points, the resolution is 2400dpi, and the resolution is 3200dpi for 70 lines/cm points

(2) output repetition accuracy

high-end exquisite printed matter, and the maximum allowable error of repetition accuracy is 5 μ m。 For general printed materials such as manuals, books and periodicals, the repetition accuracy is allowed to be 20 ~ 25 μ m。 For low-grade printed matter such as color newspaper, the allowable error of repetition accuracy is 25 ~ 50 μ m。

(3) output plus structure

can output points with different dot line numbers and dot shapes. In order to ensure that there is no obvious tortoise text or density fluctuation during color image reproduction, the output equipment is required to produce points with good printing performance

(4) output speed

output speed depends on the performance of rip and graphic recorder. Hardware Rip is fast, while software Rip is slow. On the premise of outputting color separations of the same quality, the faster the better

in addition, the output equipment should also have the ability of standard interface and Chinese character output, and the output format can meet the printing requirements

the output equipment of the color desktop publishing system also includes various color printers, such as laser printers, inkjet printers, thermal junction printers, and various multimedia carriers (slide makers, optical discs, video recorders, etc.)

IV. high end connection

the color desktop publishing system is connected with various existing models of electronic color separators, which is called high-end connection, which is another working mode of desktop system

when using high-end couplers to obtain high-quality graphic negatives, the interface of the electronic color separator must solve two key problems. First, speed. Because the control of pause cannot be achieved when the electronic color separator is in and state, the interface and interface workstation must be fast enough to accept the scanning data of the electronic color separator and send data to the electronic color separator at the same time. Second, the way of combining pictures and texts to output negatives. If the point generator of the electronic color separator is used to generate points, only a high-resolution interface is added to jointly complete the output of picture and text integration. If you do not use the point generator of the electronic color separator to generate points, and only treat the recording part of the electronic color separator as an image setter, you need to add another rip processing point and text, and the desktop system uses the electronic color separator through rip

high end connection, forming a whole page patchwork system with general-purpose computer as the core. It not only gives full play to the advantages of high input resolution and good image processing quality of electronic color separation machine, but also integrates the advantages of desktop system, which can process pictures and texts at the same time. The layout combination is flexible and fast, the artificial creativity is novel, and the whole page data can be accessed repeatedly. At the same time, it opens up an excellent way for manufacturers with electronic color separation machine to improve the ability and efficiency of color plate making