The hottest color desktop publishing technology Q

2022-08-01
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Q & A on color desktop publishing technology (II)

1. what is OPI technology? OPI (open press interface) is actually a set of annotation specifications based on postscript language. These notes indicate the relevant geometric parameters of the high-resolution file, the location of the currently saved file in the network, and other parameters related to the communication network. A dedicated workstation that can centrally manage a large amount of image data, generate preview images with OPI annotations and display, and complete output management and image replacement functions is called OPI server. The prepress system produced by OPI mode circulates on its communication network, mainly images with much smaller capacity and size and well arranged layout documents. Because the capacity of transferring files is very small, the communication speed is accelerated, and the production efficiency can be greatly improved. To save a large number of high-resolution image originals, the server needs huge storage capacity, communication capacity and the ability to control various output devices. Therefore, in the electronic prepress system composed of multiple workstations and related input and output devices, computers with high speed and capacity need to be used as servers. The design idea of OPI is based on the concept of network as the center. In the prepress system, all devices talk with the network server, and the server becomes the production hub and scheduling center. 2. What are the functions of opi/dcs server? Its main functions are: 1) image file sampling. For high-resolution images registered on the server, including those provided in tiff, DCS, Scitex CT and image compression format (JPEG, quick time), preview files with specified resolution are produced according to user requirements, and can be called by the typesetting workstation through the communication network. 2) Image file archiving management. A large number of registered image files can be managed within the network. Relevant image files can be stored in any workstation on the network, and can also be managed, queried and indexed by other image database software. 3) For the compression of preview images. If the size of the generated preview image is large, it can be further compressed by JPEG or QuickTime. 4) Queue management of output devices. The server can manage multiple post script output devices at the same time, including laser Imagesetter, laser printer (black and white or color), etc. For each device, different queues of devices can be used according to the output accuracy (such as output negative film, positive film, negative film, etc.), and the automatic management of output jobs can be realized. 5) Restricted management of output devices. Some output devices can specify a restricted user range to prevent misoperation by unauthorized operators. For jobs that have entered the queue for output, the operator can still perform management operations such as removing, deleting, and moving to another queue. 6) Image replacement on output. For the received postscript output files, it will automatically search and output and replace the relevant files with high-resolution images. 7) Job records. The operation contents of all output equipment, whether there is an error, relevant error information, output time, etc. are recorded for verification and query. 8) Color management technology. Color management technology is supported. The generated preview image is matched and converted through different equipment features according to its purpose (display or color printer proofing) to ensure a good proximity to the printed product. 3. what should be considered when selecting an OPI server? When selecting an OPI server, the following aspects should be considered: 1) types of supported file formats. Common file formats include TIFF (RGB), tiff (CMYK), Scitex CT, DCS, EPS, PDF, photocd (YCC), etc. 2) Whether low resolution images with different resolutions can be generated as required. When outputting samples to non PS color printing, only preview images can be output. In practice, South Africa often uses medium resolution to print out samples. Therefore, the OPI server should have the ability to generate the corresponding preview image according to the resolution required by the user. 3) Whether the OPI server can accurately reproduce the changes of the preview image. Since the preview image and the main image file are used independently of each other, it is very important whether the changes imposed by the user on the preview image can be accurately reproduced in the OPI server. These changes include frame rotation, image rotation relative to image, tilt deformation, scale change, text and image overlap and different masking relationships. 4) Whether the color management system is supported. The OPI server supporting the color management system can generate low resolution images that can correctly reflect the color performance of printed matter. 5) Whether it has the function of image database. When the server stores a large amount of image data, the retrieval of image files, preview of image files, and the management of text files, directories and indexes related to the development of mechanical equipment for images are also on the road of green energy conservation. They are different from common data structures and are jobs with large quantities of work. 6) Whether different types of workstations are supported. Common computer system environments in publishing and printing industry, including UNIX, Mac OS and windows systems. For the Oriental Language and text environment, the OPI server should also focus on whether to support the corresponding Chinese character environment. 7) Other functions. Including trapping, folding, and image information compression/decompression. 4. what is the desktop color separation format (DCS)? In the operation of desktop publishing system, a lot of work is typesetting. The typesetting operator completes the final design and modification of the page, and other work such as scanning, color separation, creativity and so on is for typesetting. In practice, one color separation device can meet the needs of several typesetters. According to this operation, DCS mainly solves the transmission of images between scanning equipment and typesetting workstation. Quark company of the United States, which is famous for developing desktop advanced typesetting software, has put forward an effective and unusual solution to the problem of transmitting a large number of images, and released the DCS file format, which has been rapidly popularized. There are many color image processing software supporting DCS format, Photoshop is one of them. After color separation and trimming, documents can be saved in DCS format to form a document group composed of 5 ps documents. Among them, the first one is called the master file (the application of MAS rubber spring fatigue testing machine in the field of vibrating screen), which contains the address of each color separation file, the geometric parameters of relevant images and a low resolution preview image. The other four files are the description files of C, m, y and BK color separations stored in EPS format. The master file can be used independently of the other four files. The desktop system using DCS for production operation is flexible, does not need expensive servers, and is easy to operate. Moreover, it supports images with contour lines, so it is widely used in prepress systems related to desktop systems. 5. what kinds of software are commonly used in the color desktop publishing system? The common software functions of color desktop publishing system are often similar, but the difference is that some functions are strengthened according to the purpose of use. At present, there are mainly the following categories: 1) graphics processing software. It has the functions of text input, title word, illustration and design and production of various charts. It can be expanded, reduced and deformed arbitrarily. 2) Image software. It can be used to solve the and processing of continuous tone images. It includes color correction, image adjustment, mask processing and geometric change of image. The production of special effects, including rotation, size change, sharpness emphasis and softening functions, virtual shadow generation, tone adjustment and color selective correction. 3) Color typesetting software. It is mainly used to process color layout, including making up. Typesetting software can arrange text, graphics and images in one page. 4) Color separation software. Divide RGB image form into CMYK image form. 5) Folding software. It is used to combine small pages into a large page form. 6)RIP。 It is used to process pages and rasterize them. Some Rip also includes color separation. 7) Other multimedia software. 6. what is true type glyph technology? True type (TT) is a new digital glyph description technology jointly proposed by apple and Microsoft. TT is a set of rich instructions for color digital function to describe the outline of font. These instructions include font structure, color filling, digital description function, process condition control, grid processor (TT processor) control, additional prompt information control and other instructions. TT uses quadratic B-spline curves and lines in geometry to describe the outline of fonts. Quadratic B-spline curves have first-order continuity and tangent continuity. Parabola can be accurately represented by quadratic B-spline curve, and more complex font shape can be represented by several connected quadratic B-spline curves and straight lines to meet the mathematical characteristics of B-spline curve for the inspection of residual deformation of reinforcement joints by various quality inspection units and construction sites. Files describing TT fonts (including TT font description information, instruction set, various marking tables, etc.) may be common to Mac and PC platforms. On the Mac platform, it is stored in the form of "sfnt" resources, and on the windows platform, it appears as a TTF file. In order to ensure the cross platform compatibility of TT, the data format of font file is stored in Motorola data structure (high order first, low order last). All TT interpreters on Intel platforms need to be properly preprocessed before execution. The TT interpreter of windows has been included in its GDI (graphics device interface), so any output device supported by windows can output with TT font. 7. what are the advantages of using true type technology? TT technology has the following advantages: 1) real WYSIWYG effect. Since TT supports almost all output devices, all TT fonts installed in the operating system can be output at the specified resolution on the output device regardless of the system screen, laser printer or laser Imagesetter. Therefore, most typesetting applications can accurately layout pages according to the resolution and other parameters of the current target output device. 2) Support font embedding technology to ensure cross system transmission of files. TT embedding technology solves the problem of file and font consistency across systems. In the application program, the saved file can store all TT fonts used in the file in an embedded way. Make the whole file and the font it uses easy to transfer to the same system of other computers. Font embedding technology ensures that the computer receiving the file can maintain the original format of the file by loading the TT font embedded with the file, and print and modify the original font even if the font used by the transmitted file is not installed. 3) Operating system platform compatibility. At present, both Mac and windows platforms provide system level TT support. Therefore, application files with the same name between different operating system platforms have cross platform compatibility. If PageMaker on Mac can use all TT fonts used in the file, the final output effect of the file on Mac will be highly consistent with that on windows. 4) ABC word width value. Each character in the TT font has its own word width value. The word width description method used by TT is more accurate than the traditional PS type 1

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