As the market continues to improve the quality requirements of color box products, color management has also received more and more attention. However, there are various color problems in current production. High-quality originals cannot be copied well. The quality of unsuitable originals cannot be improved after copying, which makes the original attractiveness of product packaging unable to be fully expressed, and the purpose of promotion and promotion cannot be achieved. At the same time, it increases scrap and cost, and reduces the competitiveness of enterprises. The reason is that, in addition to the problems of equipment and personnel technical level, the key lies in the failure of enterprises to carry out effective color management.
The necessity of color management
Color reproduction is the primary task of printing, and color is the core of the life and quality control of printing. However, for a long time, the colors of the original manuscript, screen display, proofing, printing and other links often did not reach the same, thus causing unnecessary disputes.
There are many variables in the production and copying process of color boxes. The pictures and texts need to go through multiple stages of scanning, processing, color separation, printing and so on. It is not easy to get the originals accurately restored. At each stage, the color information will be displayed according to the color rendering characteristics of the currently used equipment, so different scanning and display devices will have different performances on the same manuscript: In addition, the RGB color display screen and C, M, Y, K or C, M, Y, K, LC, LM color printing inks have different color expression capabilities: coupled with different application software conversion data is also lack of consistency, the use of different paper and ink to obtain printed products Different. Different types of equipment, even the same type of equipment of different models, have different expressions of colors.
Therefore, it is necessary to control the color reproduction on various devices and media in the production system by adopting color management technology to ensure that the final copy can better reproduce the original color.
The concept of color management
Color management is the correct interpretation and processing of color information, that is, managing people's perception of color. The essence is the process of converting the color data of an image from one color space to another color space under the premise of minimum color distortion, to ensure that the appearance of the color from input display to output matches as closely as possible, and finally make the original and product colors consistent .
When implementing color management, the colors in a device's color space are combined with the device's characteristic file to the intermediary color space, and then combined with the target device's characteristic file to the target device color space. Since the color space independent of the device is used as an intermediary, the consistency of colors is ensured. According to this implementation process, three elements of color management are obtained:
The device-independent color space serves as an intermediary for color conversion; for each device, there must be a standard specification to describe its color characteristics and parameters; there must be an accurate conversion algorithm to realize the conversion of colors between different spaces.
In order to standardize the standards of color management, the International Color Consortium (ICC) has formulated the ICC specifications to make every element of color management clear: the color space as an intermediary is CIEXYZ or CIELab; the file format describing the color characteristics of the device It is the format specified by the ICC; the color matching algorithm is completed by the manufacturer according to the ICC specifications.
Color management workflow
The establishment of a device's color profile (Profile) is the core of color management. The description file contains the representative color characteristics of each device, such as chromaticity characteristic curve, output color gamut characteristic curve, etc. The color management system uses these color characteristics Match and convert the color space of each device.
There are multiple workflows for color image copying based on ICC, and when the image is printed as an independent file or as an object in the page file, the specific implementation methods of color management are also different. According to the different application time of the output device characteristic file, it can be divided into early binding workflow (Early-binding workflow) and delayed binding workflow (Late-binding workflow). The former converts the color information of all images from the source color space to the color space of the final output device as early as possible; the latter defers the conversion of the color information of the image to the color space of the final output device as much as possible.
