Advanced ICC color management

Modern advanced ICC color management technology is a new type of color control method based on the change of color space. The ICC color management system is built into the computer operating system and uses a color profile (ICC profile) as a basis for color conversion. As long as any input or output device supports this format, accurate color conversion can be performed between them to enable Make color reproduction easy and quick.

A complete color management system includes feature files, profile creation software, and standard inspection color patches, color management models (CMMs), profile file connection spaces (PCSs), and application software interfaces needed to create profiles.

Color profiles play an important role in color management systems. Therefore, Profile generation software becomes the key and foundation of color management. The characteristic file includes the input device, the display device, the output device characteristic file, the characteristic file creation software required to create the device characteristic file, and the corresponding standard detection color mark.

The main developers of Profile generation software are Gretdg-Macbeth, Momaco, Heidelberg, X-Rite, and Kodak.

The standard detection color mark required to create a profile, such as the transmitted original test pattern for acquiring the scanner profile, is IT8?7/1; the reflective original is IT8?7/2. The IT8 version of Fuji, Agfa, and Monaco has 288 patches, while the Kodak version of IT8 includes 255 patches and has a portrait on the right.

The test patterns for obtaining the digital proofing characteristic file include IT8?7/3 color standard file (928 color blocks), IT8?7/4 color standard file (1617 color blocks) or ECI2002V color standard file (1485 color blocks).

The second step of color management; according to the specific conditions of each company, to take steps, sub-projects to gradually approach ICC color management, to do a condition to do one, conditional to do two, to create conditions Do two things.

1. Do a good job of digital proofing color management

At present, the color management technology is best applied to the digital proofing system, and has the most practical value. The color management software is also the most perfect and mature. Commonly used color management software such as EFI colorproofXF, true photo, GMG4.1 version. These softwares are products that are continuously improved and upgraded. They have many functionalities, wide adaptability, high efficiency and reliability, and can make the proofing results stable and accurate. The simulated printing color can reach about 95%. Due to the accuracy, stability, reliability and repeatability of digital proofing color, it provides an effective technical means for controlling the entire process quality throughout the prepress and printing process, Start a bridge. 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 so that printing can easily catch up with proofs.

2. Do a good job of monitor color management

The display is the window of dialogue between humans and computers. It is the most important pre-proofing tool for image processing, the most important key technology in color control, and the weakest link for many companies. Due to the large color difference between screen display and printing, operators are often misled and many reworks are caused. Therefore, it is important to do a good job of correcting the display and soft proofing.

Some state-of-the-art displays for image processing use high-quality monitors. They use X-Rite's Monaco Optix XR screen correction instrument, MonacoProfile color profile generation software or Gretag Macbeth's Spetrotino spectrophotometer, along with Pro-fileMaker color characteristics. The file generation software performs display correction and generation of profile files to ensure that the display has the largest color gamut and the best display. And in the Photo-shop screen soft proofing, so that the screen color and the printing color is basically close. Practice has proved that: the monitor does not do color management with or without color error, through the color management of the monitor, it can ensure that most of the intermediate tone color is close to the printing color, but in the Y, G, C 100% solid color saturation The degree reached the target value, and the blue-violet was slightly over. By finding these local color gamut error laws, we can help compensate for color processing. At the same time, it helps enterprises to adopt standard light sources for 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 the standard light source.

3. Make the scanner's color management

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

Now some high-end professional scanners have developed a distinctive color management system to make the scanning and color separation technology more standardized and color reproduction more accurate. For example: The latest SG-8060PMarkII high-end digital roller scanner is used in the full: ICC color management environment, through colorsync 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 some mid-to-low-end scanners, one is to make a good scanner correction. Use the standard Kodak IT8 7/1 transmission color scale and IT8 7/2 reflective color gray scale to adjust the highlights, shadows, and gamma in the middle of the scanning software to make the gray, tone, and color of the electronic image. Consistent with the gray scale color scale.

The second is to make scanners feature files. By testing the color performance of the scanner, a standard ICC Profile is created, which ColorSync uses to convert the color of the scanner file.

The third is the use of a good scanning profile. 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 profile (as in PhotoShop). It does not matter which method is used to combine the image with the property file. The important thing is that the property file must be linked to the image.

The scanner profile can improve the scanned image quality. Therefore, it is possible to faithfully restore scanned high-quality originals. However, the scanner's profile does not correct poor quality manuscripts. Therefore, for poorly-imaged manuscripts, it is still necessary to pass through the post-scan technology processing and the art department's stoppage.蟮 摹 摹                           鯥 鯥 鯥 鯥 鯥 鯥

1 Through the screen correction instrument's color management software, the screen is calibrated and soft proofed, giving a "what you see is what you get" display on the monitor;

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

3 Through the digital proofing color management software correction, digital proofing and printing effects are 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. In practice, the author has three understandings of ICC color management:

1 There is also instability in color management, which is caused by changes in the production environment. Such as display, scanner quality differences and aging, attenuation of light source intensity, especially the instability of the back-end printing ink, paper and printing press. Therefore, even if the color management is done well, the equipment in the process flow needs to be calibrated and corrected regularly, and the device's characteristic description file must be updated regularly.

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 preview the image color through the screen at each stage. , which can be adjusted intuitively, so that some operators without color experience can also make a better product.

3 Color management is not magic wand that people think, can copy the original color 100%, the color management system calibration is only to enable each device to achieve the original product design indicators and output accurate colors, and can not make the device output color exceed 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.

According to the company's specific conditions, the color management methods are organically combined to establish a set of more reliable color management systems throughout the prepress and printing processes, and to better control the transfer and transfer of color information during the replication process, thereby ensuring the entire The system runs smoothly.

The above-mentioned traditional excellent color control and advanced ICC color management belong to the category of reduction of the printing and copying technology, and are the scientific nature of the copying technology, and should be treated as a science.

Reprinted from: Printed in China