Where is the most popular way of color management

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Where is the way of color management

color management is a technology that converts images from the color space of the source device to the color space supported by the target device. Its purpose is to provide a consistent color reproduction mechanism across peripherals and operating platforms. China's plastic extruder market has made great progress and breakthroughs. The development of modern color management technology has experienced two stages: at the beginning of the emergence of color electronic prepress system in the 1970s and 1980s, the concept of color management has been adopted by people, but at that time, the color desktop prepress system was incompatible with each other. To complete the color transmission between different devices, it was quite complex, and it needed to use multiple unique color conversion procedures to achieve, so it was called traditional color management technology. In 1993, eight major computer and image developers established the international color alliance ICC to solve the problem of color management compatibility between new products. ICC establishes the color management system in the computer operating system, and uses the color characteristic file as the basis of color conversion. As long as any input and output device supports this format, they can accurately convert color between them, which is modern color management technology

for more than 10 years, ICC based color management systems have been widely used in various image processing software (such as Photoshop) and operating systems (such as colorsync for Mac and ICM for Windows XP). ICC feature files have also become an industrial standard. However, does this mean that modern color management technology has been fully mature? Some professionals pointed out that color management technology still needs to be further explored by insiders on the existing technology, and its development will be affected by three aspects: digital photography, cross media publishing, and customers' requirements for low cost, high quality and short delivery time. The future color management will have higher requirements on the consistency and automation of color reproduction. So what is the future development direction of color management technology

defects of modern color management technology and color appearance model

1 Modern color management method

modern color management technology starts from the color in the color space of a device, combines the color characteristics of the device, converts it to the device independent color space PCs, and then combines the color characteristics of the target device, and then converts it to the color space of the target device. The basic idea of modern color management technology is to first select a device independent color space, then characterize each device in the entire image system to form a device color description file, and finally establish a certain corresponding relationship between the color space of each device and the standard device independent color space, and use the color management module CMM to carry out color conversion

2. Defects of modern color management technology

in human vision, at the same time, the system will pop up a dialog box to specify the current yield point force value. It can be said that any color exists in the contrast state, or under relative conditions, and is shown from the whole. And human perception cannot feel a certain color alone. It is always in a large whole to feel all parts. Further, the understanding of a color is related to its existing environment. The same color has different color perception, that is, color appearance, under different lighting conditions, different media, different backgrounds, and observed by different observers. Therefore, in order to solve this problem, people have proposed a color appearance model, through which the color attributes of different observation conditions can be reproduced in a certain environment

the device independent color space PCs used in modern ICC based color management systems is usually CIELAB or CIEXYZ. CIEXYZ is not a color appearance model. CIELab color space is approximately considered a color appearance model because it can calculate lightness, saturation and hue, and has simple color adaptation conversion, but CIELab color space has the following defects

1) the hue of CIELab color space lacks visual uniformity, that is, the colors on the same hue angle in the color space do not have the same hue visually, especially in the red and blue areas. In color management, when color conversion is carried out, color matching is often carried out by keeping the hue of colors with the same hue angle unchanged and changing lightness and saturation, which requires that the color space used must have excellent hue uniformity

2) CIELab color difference formula is obtained by using a single color block under constant visual conditions, so it can only calculate the color difference between color blocks under specific conditions, but cannot predict the color difference of complex spatial images under different visual conditions

3) CIELAB is only suitable for color reproduction under constant visual conditions, and is not suitable for cross media and cross platform color reproduction

Although CIELAB is considered as an approximate color appearance model, it can only be used to predict color attributes under the same visual conditions. Therefore, it cannot be completely used as a standard color space for color conversion

3. Color appearance model

color appearance model refers to a mathematical model that can predict the relevant attributes of color, such as lightness, hue and chroma. Specifically, it refers to the mathematical formula or mathematical model for calculating or predicting color attribute parameters (such as lightness, saturation and hue) through CIE chromaticity parameters (such as tristimulus value) under specific lighting, background and observation environment. The color appearance model mainly solves the problem of color reproduction in different media under different observation conditions, different backgrounds and different observation environments

in 1998, CIECAM97S was proposed by CIE's sub Technical Committee responsible for testing the color appearance model, which has achieved great success in the research of color appearance model. At the same time, it also attracted many researchers in the industry to further study it. With the deepening of the research, researchers soon found that CIECAM97S had some shortcomings and put forward many suggestions for modification, so CIE recommended a new generation of CIECAM02 color appearance model in 2002, CIECAM02 is established based on CIECAM97S model, and a lot of modifications and simplifications have been made, including a linear color adaptation transformation, a new nonlinear response compression function, and the -60 ~ + 130 ℃ modification of the color perception attribute calculation method. However, although CIECAM02 can predict the color reproduction effect under different visual conditions, it does not combine the spatial and temporal characteristics of human vision with image visual effects. Therefore, in 2004, Fairchild and Johnson recommended image color appearance model (ICAM). ICAM combines the spatial and temporal characteristics of human vision and has good hue uniformity. It can not only predict the color features of complex images, but also measure the difference and quality of images. It is suitable for cross media image replication and high dynamic range imaging technology

color management system WCS based on CIECAM02 model

since ICC launched the first version of the feature file in 1993, modern color management technology based on ICC has always occupied a dominant position in image processing, and CIELAB has been used as the standard color space when performing color conversion. Due to the uneven hue of CIELab color space, it cannot predict the color characteristics under different visual conditions, and is not suitable for cross media color reproduction. People urgently need a new color management method to solve this problem, and the color management system WCS (windows color system) used in the Windows Vista operating system that Microsoft will launch soon is just suitable for this requirement. The introduction of WCS will have a great impact on modern color management technology, and also point out the direction for the development of color management technology in the future

the color management system WCS of Windows Vista operating system is jointly developed by Microsoft and canon. This new color management technology will provide more realistic screen effects, more comprehensive color display, and more realistic printing technology. Through the use of new tools, it can better support digital cameras, color printers and other related hardware. WCS is considered to be a dynamic color management system. It adopts a new feature file structure. The feature file is written by an R & D team with Suzhou as the main body, which can quickly connect with suppliers all over the country. The extensible markup language (XML) simplifies the process of feature file creation, inspection and. There are three types of feature files in WCS: one is the device model feature file. In order to describe the color space of the device, WCS uses Canon's kyuanos device model system to simulate the performance and technology of the device. This model can provide excellent mapping of device color and objective color. Therefore, the device feature file of WCS is based on objective measurement data; The other is the color appearance model feature file, which is used to describe the visual conditions of the source device and the target device; Another is the gamut mapping model property file, which describes how the gamut mapping model will deal with colors outside the gamut. Different from the ICC Color management method, the ICC Color management method specifies the method of color gamut mapping (such as look-up table method) when making the device characteristic file, while WCS allows users to select the color gamut mapping model and the visual conditions used by the device, making the color conversion more flexible. In addition, WCS uses CIECAM02 as the color appearance model, and all color appearance transformations are carried out in CIECAM02 color appearance model, so that the color visual attributes under different visual conditions can be predicted

wcs' color management workflow includes three steps:

1 Establish the characteristic files of equipment, visual conditions and gamut mapping, including the model characteristic file of equipment a, the color appearance model characteristic file of equipment a, the characteristic file of gamut mapping model C, the model characteristic file of equipment B and the color appearance model characteristic file of equipment B

2. Use the color architecture and conversion engine cite (color infrastructure and translation engine) and the produced feature files to establish an optimal color conversion. Just like CMM in ICC Color management system, cite is the core of WCS, which is responsible for converting source color into target color

3. Cite applies the established color conversion to the input image to establish an accurate image file for output by the output device

wcs introduced the color appearance model into the color management system for the first time, established a brand-new color management concept, broke the ICC based color management mode that has been used for more than ten years, enabled users to predict the color effects under different visual conditions, and solved this long-term problem that bothered people. Although WCS has not been officially launched, people have long waited and waited for this new color management technology. And now people have begun to try to apply the new color appearance model ICAM to color management, in order to realize the color management of cross media, cross platform and high dynamic range color replication process. With the continuous deepening of people's research, it is believed that the color management system based on ICAM or even more perfect color appearance model will be developed soon

seamless automatic color management technology

with the continuous maturity of JDF (job definition format) technology, the digital workflow based on JDF has been greatly promoted, and the realization of the real digital workflow will be just around the corner. The future color management technology will also have higher requirements in automation to meet the needs of digital workflow. Therefore, seamless automatic color management technology may be the future of color management

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