Insiders talk about color management

In today's printing industry, on the one hand, people manage the color based on color measurement values ​​(CIELab). On the other hand, in order to catch up with the trend of digitalization, they are also committed to the construction of digital colorization and standardization management. During the PAGE 2001 conference, Japanese industry professionals conducted an exchange activity on the topic of “color management to quality management” and the current trend of color management standardization with a strong momentum of development in the printing industry. Here, the author will introduce three of them.

First, the first thing to introduce is the report made by Mr. Sanzan of Canon Inc. on the "standardization trend of color management." Its main point is:
Now, the "standardization" advocated in the field of color management is not limited to the printing industry. It is attracting attention from the general public. Moreover, with the advancement of digital imaging technology, the boundaries between various imaging methods used in the industry are gradually becoming blurred, and the standards established in one of these fields will also have a significant impact on other areas.

Take the color scanner as an example. If it is regarded as an office equipment, it is examined and certified by the authority named ISO/IEC JTC 1/SC 28 Committee; if it is regarded as a multimedia content input tool, Then it will be called institutional management of IEC TC 100TA2. Take a closer look: If you look at it from a photo scan point of view, then it belongs to the scope of ISO TC 42; but if you look from the printing field perspective, it is also the process of installing it through ISO TC130 (not the hardware of the scanner ) Conduct standardized management. In short, a single scanner is so complicated that it goes without saying.

Due to the complexity of the problem, the communication between the auditing authorities is not enough or the mutual understanding is not enough. Therefore, there are frequent occurrences of adverse effects and frictions in the implementation of the standardization process. From this we can see that it is impractical to emphasize "standardization" blindly, without weighing the balance.

2. Mr. Sakai, from Fujitsu Co., Ltd. put forward a new view of “quality evaluation” on the new trend of color management and the latest status of the standardization of color measurement that is closely related to the printing industry. Its main content is:
CIE developed "BCRA Ceramic tiles" as the calibration standard for colorimeters. It defines twenty-four colors and their measured values. In the future, if the measured value of a color sample is outside the scope of this definition, it is deemed to be inconsistent with international standards. However, the “color measurement” method like this is not an ironclad, immutable thing. In the future, it is also necessary to pay attention to the standardization trend and adapt it to changes.

In addition, JTAG2, which previously existed as a management agency for ISO, IEC, etc., has been formally determined to terminate its functions in the construction of the standardization issue. From now on, the new organization SCIT (Steering Committee of Imaging Technology) will be responsible for the management of organizations other than the IEC. However, this institutional change has also brought about new problems: The IEC and other standards-related organizations (ISO, CIE, ITU, etc.) have hardly conducted any information exchange during the subsequent standardization process, resulting in their own closed doors. situation.

Recently, in the process of the standardization of color management, the so-called "quality evaluation" has emerged. Its core is to try to change the evaluation methods that were subjective in the past and introduce the objective method of “numerical expression”, that is, to subdivide the image quality into multiple observation angles, from granularity, horizontal and vertical shape, fiber overlap, Color, texture and other components are analyzed and evaluated one by one.

Through the research and published papers of academic institutions such as PICS and NIP, Kodak, Xerox, and QEA, the test chart for image quality evaluation has been published.

Third, the last point to be introduced is the opinion of Mr. Futian, a QEA Japanese firm, on the "Objective Evaluation Method for Printed Images."
QEA Corporation was founded in 1987 by Dr. Ming-Kai Tse, a professor of mechanical engineering at MIT. In recent years, it has been mainly engaged in the manufacture and sales of automatic test systems for digital printers. QEA's business philosophy is to "Turn abjectives tinto numbers" (from adjectives to specific values), that is, to change the evaluation methods of image quality now centered on subjective evaluation, instead of objective evaluation methods and provide relevant automation. system.

The basic principle of image evaluation advocated by QEA is to subdivide the elements that constitute the image quality and evaluate them one by one, and make a comprehensive judgment based on the results. These elements mainly include: characteristics of blueprints, leakage between colors, hue, the scope of color expression, and binding.

As for the calculation method of the image quality evaluation, the ISO-13660 certification body is now conducting research on the close-in and blue-print characteristics. QEA also participates in the discussion as a member. Although companies have conducted secretive research on their own evaluation criteria or numerical methods, people have noticed that these research activities are developing along with the development of ISO's standardization process.