Establish a color management system with the characteristics of the company (2)

Modern and advanced ICC color management technology is a new color control method based on the change of color space. The ICC color management system is built into the computer operating system and uses the ICC Profile feature file as the basis for color conversion. As long as any input or output device supports this format, accurate color conversion can be performed between them, making it easy and quick Complete color reproduction.
A complete color management system includes the ICC profile properties file, profile generation software, and standard inspection color patches required when creating profiles, color management models (CMMs), profile file connection spaces (PCSs), and application software interfaces. The ICC profile profile plays an important role. Therefore, profile generation software becomes the key and foundation for color management. The ICC Profile feature file includes the input device, display device, and output device profile.

The main developers of the profile generation software are Gellinger Macbeth (acquired by X-Rite, its holding company Amazys in January 2006), Heidelberg, X-Rite, and Kodak.

There are different versions of the standard detection color patches required to create the ICC profile properties file, such as the transmission original test pattern for acquiring the scanner ICC Profile property file is IT8.7/1; the reflection original is IT8.7/2. The Fujitsu, Agfa, and Monaco IT8 maps have 288 color patches, while the Kodak version of the IT8 map includes 255 color patches and has a portrait on the right side.

Get the digital proofing ICC Profile characteristic file test chart IT8.7/3 color marking document (928 color patches), IT8.7/4 color marking document (1617 color patches) or ECI2002V color marking document (1485 color patches ).

The second step of the author's color management: According to the specific conditions of each company, adopt phased, sub-projects to gradually achieve ICC color management.

1. Make digital proofing color management

At present, the color management technology is best applied in the digital proofing system, and has the most practical value. The color management software is also the most perfect and mature. The resident offices of the author use color management software such as EFI Colorproof XF, Fangzhen Photo, and GMG 4.1. These softwares are products that are continuously improved and upgraded. They can achieve many functions, wide adaptability, high efficiency and reliability, and can make the proofing results stable and accurate. The simulated printing color can reach about 95%. Digital proofing, due to its color accuracy, stability, reliability and repeatability, provides an effective technical means for controlling the quality of the entire process and sets up a bridge in every aspect. It can not only provide reliable parameter basis for front-end image processing, but also provide customers with standard proofs to confirm the quality of image processing, and provide standard proofs for printing, making it easy to catch up with printing.

2. Do a good job of monitor color management

The display is the window of dialogue between people and computers. It is currently the most important pre-proofing tool for image processing, and it is the most important key technology in color control. It is also the weakest link for many companies. Due to the large color difference between screen display and printing, Often misleading operators, causing many rework. Therefore, it is very important to do a good job of correcting the monitor and soft proofing the screen.

Some state-of-the-art monitors for image processing are of a better quality. They use X-Rite's Monaco OPTIX XR screen correction instrument, Monaco Profile feature file generation software, or Sperrolino spectrophotometer from Gellinger Macbeth to match Profile Maker color. The profile generation software performs the display calibration and ICC profile generation to ensure the monitor has the largest color gamut and the best display. And in the Photoshop screen soft proofing, so that the screen display and the printing effect is basically close. Practice has proved that: Through the display's color management, you can ensure that most of the intermediate tone color is close to the printing color, but in Y, G, C 100% solid color gamut saturation does not reach the target value, while the blue and purple are slightly Some too. By finding these local color gamut error laws, we help compensate for color processing. In addition, companies need to use standard light sources in the display environment and use a hood on the display to reduce the interference of external light sources on the color of the display image and ensure that the colors of the display are basically the same under standard light sources.

3. Make the scanner's color management

Scanning color separation of the analog manuscript is the first step of copying. It is crucial for the scanner to faithfully reproduce the color gradation information in the image during the process of color management and digitization. In practice, the author realized that to print a good product in the end, all the information needed for the product must be obtained from the original when scanning. This is like recording music, first the microphone is better, otherwise, There is no way to talk about quality. Therefore, it is an important step to calibrate the scanner and use the scanner's ICC profile to perform an accurate scan.

Now some high-end professional scanners have developed a distinctive color management system, make the scanning color separation technology more standardized, and color reproduction more accurate. For example, the latest SG-8060 PMARKII high-end digital roller scanner adopts the full ICC color management environment and uses Color Sync color management technology to achieve accurate color reproduction. At the same time, monitor correction is also provided to effectively match the display with printing, and a correct color profile is created through built-in Fit software.

For middle and low-end scanners, one must do a good job of scanner calibration. Use standard Kodak IT8.7/1 transmission color scale and IT8.7/2 reflection color scale, gray scale, and adjust the highlight, dark tone, and intermediate gamma in the scanning software to make the gray and step of the electronic image. The tone and color are consistent with the gray scale and the color scale. The second is to make the scanner ICC Profile feature files. By testing the color performance of the scanner, a standard ICC Profile Color Sync is created to convert the color of the scanner file. The third is to use the scanner's ICC Profile feature file. One is to embed it in the image, which is applied directly to the image through scanning software. The second is to select the appropriate image and ICC Profile properties file. It does not matter which method is used to combine the image with the ICC Profile. It is important that the ICC Profile must be combined with the image.

The author realized that the scanner ICC Profile feature file can improve the scanned image quality. Therefore, faithful restoration of high quality manuscripts can be achieved and the effect is very good. However, scanner ICC Profile feature files cannot correct originals with poor quality. Therefore, manuscripts with poor image quality still need to be processed through post-scan technology processing and artistic processing to be able to outperform originals and meet customer requirements.

Through the above ICC color management basically achieved 3 goals:

1. Through the screen correction instrument's color management software, screen correction and soft proofing;

2. Through the color space conversion, the results of the color information data conversion remain basically stable and consistent;

3. Through the correction of the color management software, the digital proofing simulation printing effect is basically close.

In the entire process, as long as the basic three points above, then the color management will play a role in quality control.

The author has three points of understanding of color management in practice.

1. There is also instability in color management. This instability is caused by changes in the production environment, such as differences in the quality of monitors, scanners, and aging, attenuation of light source intensity, and especially printing inks, papers, and Printing machine instability. Therefore, even if the color management is done well, the equipment in the process flow needs to be calibrated and corrected on a regular basis, and the ICC Profile feature description file of the device must be regularly updated.

2. The practical significance of current color management is to provide a monitoring method for the entire printing process flow, which can control the color transfer in the process of scanning color separation, image processing and production, and can predict the image through the screen at each stage. Colors can be adjusted intuitively, so that operators without color experience can also make better products.

3. Color management is not the magic wand we imagine. It can copy the original color 100%. The correction of the color management system just makes each device achieve the original product design index and output accurate color, and can not make the output of the device exceed the color Its color range. And its importance lies in the data control of the entire prepress process to ensure the accuracy and stability of color reproduction.

To sum up, companies must organically combine the above two color management methods according to their specific conditions, and establish a set of more reliable color management systems throughout prepress and printing processes to better control the color of the replication process. The conversion and transmission of information ensure the smooth operation of the entire system.



Source: Digital Printing