Color Management - Realize color reproduction in the end

The vivid colors are always the dreams that the printing practitioners can't reach. Why the splendid designs of advertising designers can't be reproduced in prints. The bright colors go where they are, and they are eaten by paper and ink. Did you lose it? In order to accurately display the color seen on the display on the printing press, the word “color management” has been increasingly mentioned by everyone. The related standards and implementation methods of color management have become the current seminars. Hot topics. Prof. Luo from the University of Leeds, UK, is an expert dedicated to the field of color management. He talked about the CIE CAM 02 (Color Appearance Model), a newly-launched CIE (Color Appearance Model)-color appearance model. His words are like a river. Incessantly.

Today's global printing industry is undergoing tremendous changes every day. Every device manufacturer in the digital service industry has its own system standard in color management. Six years ago, ICC was established. How to carry out effective application of color management, the most important thing is to establish a worldwide standard, and the joint part is how to apply Color Appearance Modeling. The CIE CAM 02 color appearance model standard that was born just recently brings color management to a higher application realm.

In any kind of object in nature, the appearance of color can directly express the characteristics, and the appearance of the color of the commodity is a direct influence on the desire to attract the purchase. However, many people have not noticed that the visual appearance of color will have a great difference with people's external environment. From the figure below, we can see that the same white square gives different visual perception to people in different background colors.

Color science refers to the standardization and digitization of any color after photometry. The tool parameter for implementing this technique is CIE Lab. The color is described and defined by X, Y and Z parameters. The CIE Lab color space belongs to the psychological color space. In the two-dimensional coordinate system of a and b, +a indicates red. , -a indicates green, +b indicates yellow, -b indicates blue, and the lightness of the color is represented by the percentage of L.

L, a, b three parameters can describe any color information, so establishing a universal color standard is very important for different color equipment suppliers around the world. With the advent of the digital information era, many display media have developed rapidly in terms of the authenticity of color performance, making the old CIE standard unable to adapt to the development of new technologies. After the color designer designs a satisfactory work on the display, he will not only become a printed matter, but may also express his idea of ​​color expression on plastics, glass containers, clothing, paints, and other carriers. New problems arrived.
Originally, color science told us that if there is a pair of colors, if the three values ​​of X, Y, and Z are the same, the colors will match. Now, we need to look at the colors on the display, clothes, and printed matter. How to make the colors of different carriers achieve a consistent effect involves the concept of color exchange. For the color of the media color, the test conditions of the old CIE standards are mostly based on the same light source, the same illumination, and the same object, but there is no solution to the cross-media color management. In this environment, we introduced the prototype of the definition of CAM in 1997 and formally decided on the International Commission on Illumination in 2002. Almost all imaging product manufacturers such as Hewlett-Packard, Sony, and Epson are developing and manufacturing products based on this standard.

In the traditional printing process, the color of the printed matter may also be different due to different lighting conditions. The CIE is an organization that provides uniform color standards for different media from input to output. When the color on the display is actually displayed on the printed matter, the management process for any color needs to undergo the following steps. Firstly, the color is corrected, the color RGB information is converted into a standard form of the CIE, and the second step is Compression of the color gamut, because the range of colors that the ink can express is very limited, the color range of the display needs to be equal or relatively compressed, so that all colors can be reproduced through the ink. The Color Appearance Model is particularly important here. It is the link between the RGB color information and the CMYK color information. The ICC Profile we hear often is the data file of this model. The ICC profile is like a special file storing all color data information and addresses. The output and input information are re-measured and converted here to redefine the color properties of the image, thereby standardizing the color information on different displays. Make sure that the appearance of color is uniform.

Imagining the future of color science is no longer a complex and complex transformation of the colored space. The color appearance of any media can be transformed and expressed as a unified standard. Color is no longer the bottleneck of the printing process. Gorgeous and gorgeous natural scenes can be seen on the display or on the press. What we see is what we can get!

Reprinted from: China Digital Arts Online