Monitor: Screen Soft Proofing Window (4)

The key technology of the screen soft proofing lies in the accurate correction of the screen and the color management of the prepress and printing links. Among them, the correction of the screen is to test and adjust the display. Just as the experimental instrument must be zeroed before use, the monitor also needs to be calibrated to adjust to the standard state that matches the printing condition cabinet, which is in line with the actual work environment, otherwise it will greatly affect the role of the screen soft proofing in color management and proofing.

1. Unpacking acceptance is crucial

Associate professor Gu Wei of the School of Printing and Packaging Engineering of Xi'an University of Technology reminded everyone that when the monitor is unpacking and accepting, it is very important to adjust the gray balance, brightness and saturation. Although the device manufacturer has already set color settings when the display is shipped from the factory, due to the extremely strict requirements for color printing, such conventional factory settings are still not up to the requirements, so early adjustment is of utmost importance. And if you can adjust it properly for a long time, you only need to perform a simple correction on the monitor periodically, and then find a big deviation and readjust it.

2.1:1 advantages of browsing and correcting

The current trend in the display market is "big, short, and flat," where "big" means that the display's screen is getting bigger and bigger. Today's screens for soft-proofing monitors have increasingly larger screens and constantly refresh records. Why is it getting bigger and bigger? Because in the printing process, whether it is processing the image after the power extension scanning, or outputting the group layout to the display, the operator hopes to be able to browse 1:1. Because arbitrarily zooming in or out of an image inevitably results in a change in the color of the reproduced image of the screen, if it can be displayed in 1:1, the operator can easily and accurately adjust the amount of ink.

3. Display correction and description

The calibration and description of the display are accomplished by software and a corrector. Most color management software currently has a display correction module. Using this function, a series of color values ​​containing printing conditions and printed material information are transmitted to the screen. The corrector then returns the measured data to the computer, and based on this, establishes a correct color description file (1CC Profile). The color management system then drives the display through the ICC Profile.

Currently, there are different levels of monitor adjustment systems on the market, some are software only, some are software-based hardware (colorimeter or spectrophotometer), and some are even sold together with monitors. Many monitors have screen calibration tools. If the monitor does not have a built-in calibration system, a set of calibration tools is required to ensure stable output. For example, P臼ntone's SpYder叩O screen correction software, X-Introduction Te (X-Rite) has several independent calibration tools such as the Co-OPT, X-screen colorimeter and GretagMacbeth's Eye-One Pro spectrophotometer. At the same time, third-party services can also be introduced to complete the adjustment of the monitor.

The display is colored by the RGB additive method. Although the display after the general color correction has a good display effect, it is displayed due to the physical characteristics of the final printed product (such as ink, paper, etc.) and its color rendering method. The effect will inevitably have consistency with the printing effect. The Kodak Poly Lighting (KPG) Matchprint VrtuaI Virtual Proofing System allows the monitor's RGB color system to accurately and reliably predict the color of final prints copied from the CMYK color system in an offset printing environment, ensuring a perfect display and color workflow Integrate and get accurate colors from the screen.

4. Monitor detection environment

In order to obtain accurate screen soft proofing, it is also important to test the environment in addition to the monitor that adjusts the prosecution. Some suppliers integrate the monitors with standard light sources, shading plates, and other auxiliary equipment to meet the requirements of screen soft proofing on the detection environment. Because the contrast of the screen will be reduced under strong light, even the most accurate display requires a relatively dark working environment. Usually, the workroom only has about 20 lumens of light behind the monitor-oriented worker, and the light color temperature is preferably 5000K. The wall is preferably neutral gray to prevent the light reflected from the wall from affecting the display screen. colour.

(4) Concluding remarks

The color display is in the middle of the input and output throughout the prepress workflow. Through the display, we can immediately observe the actual results that will be displayed after printing or printing in the future. In the process of soft proofing of the screen, whether the display can accurately display the input original or accurately predict the color effect of the output result will directly affect the accuracy of "what you see is what you get" in the entire color management system.

Processing images with Adobe Photoshop, checking layouts with Adobe InDesign, and remote proofing with KPG Matchprint VirtuaI, in many cases we intentionally or unintentionally use monitors to perform soft proofing on the screen. Faced with the upcoming era of screen soft proofing, during which the development of the display has never stopped, the advancement of its technology will effectively promote the promotion of screen soft proofing in the country.

(author/xiaodan)
Sources of Information / Printing Technology 2005, 10 (Publishing and Commercial Printing)