Feel the color management around you (3)

3. Standard and specific color profiles

It is not difficult to know from the above analysis that the CMYK color space and color profile are limited by the equipment and technical conditions. Different equipment technical conditions should have corresponding color characteristics. Not only every printing equipment, even the same material used in the same equipment, even operating conditions, will bring about changes in the color characteristics, all need to re-defining the color profile. This brings a lot of trouble to the application and popularization of the color management system.

So people envisage whether they can develop a common standard, and everyone follows this standard. Photoshop does have some default criteria that can help when it is inconvenient to determine device characteristics. There are multiple choices in CMYK in Photoshop Color Settings, such as color profiles for countries such as Japan, Europe, and the United States, as well as coated paper (coated paper) and non-coated paper (offset paper), reels Different color profiles such as paper rotation and sheetfed printing. These color profiles are based on the printing equipment, paper, ink, and other conditions used in these countries or regions. At the same time, it also determines the result of four-color separation.
Since Japan's preference for image colors and the technical conditions of the printing industry such as paper and ink are similar to those in China, it is usually the case that domestic companies will select Japan's relevant CMYK color document, the female worker apan Standard v2 (Japanese Standard 2). ). The relevant description of this standard is: "In the following printing conditions, use the standardization designed to generate high-quality color separation using Japanese standard ink, 300%, the overall ink coverage area, genuine, coated material PRINTINGFI LD2007.4NO .253 material.' After selecting the relevant color profile, you can check the black and white field of the image level to find out the color profile for the black and white field settings of the image. For example, Japanese Standard 2 and white field is C: 3%, M: 2%, Y: 2%, K: 0%: while the black field is 75%, M: 68%, Y: 67%, K: 90%. The total amount of ink is 300%.

It is generally believed that general standards can be adapted for most applications. Therefore, the establishment of a common standard cannot be considered only when the technical conditions of the equipment are excellent, and it must be taken into consideration. For printing facilities that have been used for more than three or five years, their color characteristics are definitely inferior to the new ones. The general performance is that the image highlights can not be completely displayed, and the dark spots and pastes are hidden. As a result, the image level is lost and the contrast is reduced. The use of a softer lining, an increase in the amount of ink, or an increase in the printing pressure also causes problems such as an increase in the dot gain value, a dark tone level, and a paste. Japanese Standard 2 can satisfy the general workflow of equipment technical conditions and general commercial printing products. If the technical conditions of the equipment are good, if this standard is adopted, the quality of the product is also normal and the advantages of the equipment technology cannot be reflected.

JapanColor2001Coated, JapanColor2001Uncoated are color profiles using coated paper (coated paper) and non-coated paper (offset paper), respectively. The former is the same as Japanese Standard 2 printed on coated paper. Other conditions are the same, but the total amount of ink is different. Japanese Standard 2 is 300% and JapanColor2001Coated is 350%. The total amount of ink determines the black level of the image reproduction tone. The larger the black field, the larger the gradation range that can be copied, the larger the image contrast, and the higher the level of performance. Image contrast is an important basis for measuring the quality of image printing and copying. Obviously, this standard is formulated to meet better and higher product quality requirements than the Japanese standard 2 equipment specifications.

In addition to the black field, the technical condition of the equipment is different, and the white field of the reproduction tone is also different. The white field is the starting point of the hierarchy. If it is not properly set, it will result in the loss of extremely high light points and the absence of nets, which will damage the high light level. In addition to the aging of the printing equipment, the printing pressure is not uniform and the small dots are easily lost. In addition, the poor control of the positive printing plate also makes it easy to lose the small dots. At the same time, the enlargement of high-light outlets is much larger than that of medium-dark outlets, and therefore it is also a consideration. Aging of printing equipment often uses methods such as increasing the printing pressure or using a softer lining, which often leads to an increase in dot gain. The black and white fields determine the starting and ending points of the image gradation, determine the image contrast, and can help the image color to be correctly restored. It plays a key role in the quality of the image print and copy, so it must be set correctly. Although preset black-white fields have been set in the preset standard, they can be reset according to actual conditions and needs during adjustment of the tone.

Photoshop has set some color profiles to choose from, but due to the diversity of device technology, these alone are far from meeting actual needs.

In addition to the standards set for satisfying general product quality, even documents set up for high-quality products can only be taken into consideration and dwarfed by tall people to meet the needs of most equipment. To sum up, if you want to fully express the true level of technical conditions and quality of equipment, at the same time, in order to truly represent the role of the color management system in image printing and reproduction, specify the color of a specific device for a specific device and a specific production process. The configuration file is required.
For example, the above Japanese coated paper standard and offset paper standard seem to adopt higher standards. For example, the total amount of ink used in the coated paper is 350%, which indicates that this standard improves the performance of darker levels. However, the white-field setting is still 2%, 3%, and 3%. It also shows that this standard still takes care of the machines with a longer life span.

With the use of preset standard documents, there is also a problem that you must use the standard paper, ink and other conditions. Domestic printing papers, such as coated paper, offset paper, and inks are similar to Japanese standards. In the case of uncertain specific equipment conditions and color characteristics, the use of Japan-related standards can basically meet the general commercial printing requirements. This standard can also be used as a reference for image processing and adjustment, but no conversion mode can be replaced once the exact device characteristics file is available. Obviously, if there is a high requirement for the quality of printed products and they expect to be able to truly represent their own technical capabilities, they should understand the status of their own equipment and have their own device's color profile. The device's color profile, tailored for its own device and workflow, can also be loaded into Photoshop's color space, or digital printers, imagesetters, and platesetters. Its specific use is the same as the preset color profile.