Color Management Implementation Method and Experience (2)

two. Establishing a standard color environment The implementation of color management requires first of all having a stable color environment so that the effect of observing the original color, the screen color, and the print color is uniform.
1. The use of standard ambient light sources to observe color is inseparable from the light source, in order to accurately distinguish colors, standard light sources should be used. At present, many companies do not have color standard light sources, which seriously affects the reflection drafts and the color of printed materials. Therefore, due to the difference in the color temperature of the ambient light of the observation sample, the customer often causes rework due to color differences, and also affects the colors displayed on the monitor. Causes errors when adjusting colors. Therefore, it is important to use a standard ambient light source to keep the light in the room constant.
One of the key components of the standard light source is the high color temperature. Currently, domestic and international regulations require that the color temperature of the light source used for the observation of the reflective sample be 5000 or 6500K. The second is that the color rendering index is high, usually >95% of fluorescent tubes. The life of the standard light source fluorescent tube is generally 2000 hours, more than 2000 hours, its color temperature, color rendering index will be reduced, the observed color is not accurate, it should be replaced.
The fluorescent lamp of the German JUST company is generally used. Its color rendering index is 97%, and it can basically reflect the true color of the object.
2. Color standard transmission light source to observe the transmission of the original must use a transmission standard light source, so that it is consistent with the observation of printed matter, domestic and foreign regulations using 5000K (D50) fluorescent tubes. Some units use the CPM (Mini) series of transmission standard light sources. Its illumination is very uniform, soft, and small and exquisite. Its thickness is only 4 centimeters and weighs only a few kilograms. High-speed color accuracy.
The use of standard light sources is not only the need for color management, but also the need for customers to proofread their colors, as well as the need for company progress. Today, it is time for such an important standard light source with a small investment, and it is time for improvement. I hope relevant business leaders will pay attention and adopt it.
three. Complete color measurement instruments and control tools Image copying is a systematic type of work in which the originals are scanned for color separation, screen display, output film, PS printing, proofing, and printing. They are all interconnected and interact with each other. Need to regulate the operation, to quantify the color and precise control of the data, which requires the use of professional color measurement instruments and tools to effectively detect and control the copy process, to ensure the quality of the excellent and stability. The following measuring instruments and control tools are essential.
1. The most accurate way to perform color management with a spectrophotometer is to obtain spectral data and use a spectrophotometer to perform color measurements on the 928 color samples in the IT8-7.3 standard color scale produced by the output device. The results are in accordance with standard data. After comparison, a new spectral residence is obtained and an output device Profile is created. If the investment is difficult or not, you can use the spectrophotometer provided by the company when buying a digital proofing system.
General use of the United States X-Rite DTP41 automatic scanning spectrophotometer, can provide non-spectral data, a variety of density values ​​and color capabilities, can measure 480 color within 5 minutes on A4 paper or within 8 minutes Measure 800 color patches on A3 paper.
2. The screen calibrator is used to correct the screen color, and it is adsorbed on the screen by the sampling head of the calibration instrument, and the screen ...... te Color Monitor Otimi Zer screen correction instrument, and some spectrophotometers can also be used as screen correction.
3. Reflective densitometer is used to measure the density of the printing ink, printing four-color ink, dot gain, overprint and relative contrast, etc. to control and stabilize the quality of proofing and printing.
The newly-developed DigiDensT6CR handheld color reflection/black-and-white transmission densitometer from Denmark's Yanjing Deneuve is a multi-functional device with the latest sensors and micro-processing technology that can accurately measure various functions such as density values. There are 5 different display modes in the color reflection operation mode, the reflection density range is greater than 2.5, and the four-color density can be displayed at the same time.
4. The transmission densitometer is used for the linearization of the laser image-setter, one is to measure the maximum density value of the output film and the bottom ash value of the white film base; the second is to measure the value of the network points from 2%, 50%, and 98% at each level. Level points reach the standard value.
The commonly used Digi DensT6R black and white transmission / reflection density meter can accurately measure the density value and dot value, transmission density is greater than 6.0, density deviation +-0.01, dot percentage deviation +-05%.
5. The Bruner control bar is used for measurement and control of technical parameters such as proofing and printing density values, and dot gain values. It is a control tool prescribed by the national printing industry and generally uses an extended 85 control bar, which has five functions: Four-color overprint color marking section, neutral gray balance section, multi-use round control section, printing version control section, relative contrast control section.
6. The print control strips are used to control the correct exposure time and development time of the printing version. At present, UGRA control strips are widely used at home and abroad, and the quality of the printing plates can be controlled very accurately and sensitively. It has 5 control sections: continuous density section, yin and yang concentric circle segments, full-scale wind adjustment points, and ghosting with the same light and dark tone control section.
7. Gray scale and color scale standards Gray scale scales and color scales measure and control the gray balance and color sample positive quantities, and are important tools for ensuring the accuracy and stability of color reproduction. At present, Kodak'Agfa'Fujiyp 3pe wcngr IT8 standard transmission, reflection, gray ladder and color mark are used at home and abroad, and used to create a profiler profile file.
To sum up, the color measurement instruments and control tools needed for a complete color management system are indispensable. Its investment is small, and it is very easy for leaders to attach importance to it.
Fourth, to ensure the accuracy and stability of the output color The color management system running in the color desktop system requires output, printing, proofing and printing quality stability, in order to ensure the accuracy of the output color, color management is the output device on the one hand Controls and standardizes, establishes the document, namely target characteristic file, make it integrate into the color management system to run.
1. Correction and description of proofers and printers Color proofs, whether analog or digital, or prepress proofs or proofs, are key tools for monitoring and answering part of the common problem. To ensure the proofs are accurate, their important roles are:
1) Match the color of the screen, scanner, and digital printer to match this Profile.
2) The printing personnel should be used to guide the control of printing quality such as ink density, gray balance, color saturation, etc. to match the two.
Therefore, to output accurate color proofs, one must correct and stabilize conditions for proofers and printers. The second is to establish a proofing profile file, and there must be multiple characteristics files to describe the color characteristics and color gamut range of various paper, ink and other combinations. (To be continued)