Detailed explanation of the implementation technol

2022-09-26
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In recent years, with the extensive application of CTP technology, the continuous development and improvement of display technology, color management technology, digital technology and file exchange format and network technology, soft proofing technology has obtained unprecedented development opportunities, has become increasingly mature, and has been applied to the production field. Soft proofing is a new proofing method, which has the advantages of fast proofing, convenience and low cost. It has attracted more and more attention, especially with the advantage of network, it can realize the function of Remote Proofing. Therefore, soft proofing not only realizes the so-called WYSIWYG concept, but also brings a more effective way of communication, a more effective process and production management concept

basic principle of soft proofing

soft proofing is also called screen soft proofing, which is a proofing method that simulates and displays the printing output effect on the display. Through the color correction and color management of the display, the display effect between the displays is consistent, and the color displayed by the display is consistent with the color reproduction effect of the print. It has the advantages of intuitive convenience, fast and flexible, cost saving and improving production efficiency

the basic requirement of screen soft proofing on the display is that the display can accurately and stably simulate the color of printed matter, which requires that the display has a wide enough color gamut to cover the color gamut that can be presented by the printer. Such high requirements are still difficult for ordinary monitors. At the same time, because the color reproduction principle of the display and the printed sample is different, the observation conditions are also different, so the human eye's color perception of the two will also be affected. Therefore, the screen soft proofing is still lacking in the reproduction of metal color, spot color, fluorescent color and so on

the soft proofing process needs two color space transformations: one is the transformation from the color space of the source file to the color space of the target output device (printer); The other is the conversion from the color space of the target output device (printer) to the color space of the display

the whole process of implementing independent accounting in soft proofing finance can be roughly divided into three stages: first, calibrate the display and printing machine, and generate the characteristic files of the display and printing machine; Second, the printing machine characteristic document, so that the display effect of the standard document on the display is as consistent as possible with the printing effect; Third, adjust the printer during printing, so that the printing reproduction effect of the image is consistent with the display effect on the display applied with the display and the printer characteristic document

key technology for the realization of soft proofing

in general, the realization of the ideal screen soft proofing effect should be based on high-quality displays, with mature color management technology as the key, and with precision measuring instruments and software as the guarantee

1. Display technology

in the field of publishing and printing, CRT (cathode ray tube) and LCD (liquid crystal) displays are usually used. Among them, the structure principle of CRT display is that the electron gun is composed of filament, cathode and control grid. After being powered on, the filament heats up, the cathode is excited and emits electron flow. The electron flow is accelerated by the internal metal layer with high pressure, and is transmitted and focused into a very fine electron beam by electrons, which bombards the fluorescent screen, causing the phosphor to glow, and the R, G and B fluorescent dots are lit by the electron flow with different proportional intensity to produce various colors; The principle of liquid crystal display is to use the physical characteristics of liquid crystal, in the external electric field ★ 5) one-way maximum tensile or compressive static load: not less than ± 100kN; Under the action of, the arrangement direction of liquid crystal molecules changes, so that the R, G, B three color filter film and liquid crystal molecules work together to make the display color. Its main parameters include visual angle, brightness, response time, display pigment, etc

the premise of soft proofing is to have a high-quality display, and it is required that the size of cathode ray tube display and liquid crystal display used should not be less than 17 inches, and the resolution should not be less than 1024 768dpi. At the same time, it is required that the color gamut range of the display for soft proofing must be greater than the printing color gamut range to be simulated, which is the basis for ensuring the complete and accurate reproduction of the printing color gamut, It is also the premise to ensure the feasibility and effectiveness of soft proofing

not all types of monitors can be used for screen soft proofing. In recent years, with the continuous development of display technology and the highlighting of LCD's advantages such as low energy consumption, low radiation, high color stability and declining price, LCD has gradually become the mainstream display used in soft proofing. At present, the manufacturers of high-end displays mainly include apple, Japan Yizhuo, Barco and Sony

2. Color management technology

color management is a technology about the correct interpretation and processing of color information. It is a method to convert the color data of an image from one color space to another on the premise of ensuring the minimum color distortion, so as to ensure that the appearance of the color of the same image in the process of input, display and output is matched and consistent as much as possible. Color management is generally divided into three processes: equipment calibration, characterization and color conversion. The color management system takes CIE LAB chromaticity space as the reference color space, records the color characteristics of input devices or output devices with feature files, and uses application software and third-party color management software as users' color control tools

screen soft proofing is based on color management. It realizes the characterization of display, printing machine and other equipment, reduces the movable table to its original position, and realizes the mutual simulation and conversion between the colors in the display gamut and the printing machine gamut. It is the key to achieve high-quality soft proofing. But the soft proofing of the screen is not only the color management of the display and the printing machine, but must be based on the comprehensive color management. The color management of each link of the printing process must be carried out to unify the color of the whole printing process, so as to achieve the effect of soft proofing of the screen

① display correction

display correction mainly refers to the test and adjustment of the display to make its characteristics conform to the equipment characteristics of a certain state, or produce new equipment characteristics that conform to the current working state

the calibration of the display should first standardize the placement environment and lighting conditions of the display to ensure the accuracy of color reproduction; Secondly, it is necessary to ensure that the correction of the display is carried out under the stable working state of the display, that is, full preheating should be carried out before correction; Third, when correcting the display, the correct setting of parameters is the most important. The parameters such as gamma value, white field color temperature, brightness/contrast should be set reasonably according to the type and current state of the display; In addition, as the display hardware and color rendering performance will fluctuate over time, the display should be corrected regularly

② printer calibration

the final purpose of screen soft proofing is to achieve the consistency between the display effect of the image on the display and the reproduction effect of the printed matter printed by the printer. Therefore, only the display is calibrated, and obtaining a qualified display cannot guarantee the final quality of screen soft proofing, so the printer must be calibrated

the key control parameters of the printing machine mainly include printing pressure, printing speed, ink balance and registration control. These parameters can be obtained by measuring the color deviation, field density, dot expansion, overprint rate, printing contrast and other parameters of the printing test sample. Through the analysis of these parameters of the test sample, the printing machine operator adjusts the printing machine, Until the performance of the printer reaches the normal printing level, then print the test sample again, measure the relevant data, and make the ICC document of the printer. The production of printing test samples should fully reflect the current working state of the printing machine, and it is best to choose the existing standard color code, such as it8.7.3 color code document

3. Measuring instruments and software

in addition to the display and certain color management technology, the realization of the whole soft proofing process must also have the matching precision measuring instruments and software with perfect functions, so as to ensure the accuracy and accuracy of the measurement data and the effectiveness and robustness of the screen soft proofing function

at present, there are many kinds of commonly used color management software. The functions and use methods of each software are similar, and the color management effect is basically the same. The commonly used professional equipment characterization software mainly includes a series of software provided by Heidelberg company, gelinda company, azri company, screen company, etc., such as viewopen and printopen of Heidelberg company, colorshop and Monaco Optix of azri company, Gretag profilemaker of gelinda, etc

commonly used measuring instruments mainly include X-Rite dtp94 screen calibrator, X-Rite dtp92 spectrophotometer, X-Rite 530 densitometer, X-Rite dtp41, eye one Pro spectrophotometer, etc

at present, there are many commonly used soft proofing software. The soft proofing software that has passed the international certification of swop mainly includes ICs remote director, Creo synapse insite, KPG matchprint virtual and dialogue software of dalim software company

summary

screen soft proofing technology plays an increasingly important role in the color management system of printing production. The realization of screen soft proofing benefits from the continuous development of display technology, the continuous improvement of color management technology, and the continuous improvement of matching measuring instruments and software. Effective screen soft proofing can not only provide more valuable information for printing, assist printing operators in effective color management, but also facilitate communication with customers, so that customers can timely understand the production status, check the production process at any time, correct errors, and avoid basic utilization: tensile strength and deformation rate, breaking force, 180 stripping, 90 stripping fees and repetitive work, reducing production costs, Improve work efficiency. Printing enterprises should know more about this technology, and then apply this technology in actual production to innovate the printing process and service mode of enterprises, so as to comprehensively improve the product quality and enhance the competitiveness of enterprises. Screen soft proofing improves the digital workflow, conforms to the development direction of modern printing technology, and is bound to have broad prospects for development

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