Thinking of High-fidelity Color Printing Technology

Now many people have already seen high-fidelity color printing technology proofs or printing products, I believe that their effect will leave an unforgettable impression. Many of the industry's older generation of masters have applied Xiao Hong, Xiao Lv, and Xiao Lan to increase the color saturation of printed products. They believe that they have a deep understanding of the effectiveness of high-fidelity technology. The modern high-fidelity color printing technology can effectively maintain the stability of neutral gray while improving the color saturation of the printing color; it can turn the experience of the master teacher into a standardized method for more enterprises to use; More ink, or replacement of the ink used in the original custom, to achieve personalized color printing and reproduction of images, improve the printing design and product added value; can control the visual effects of printing color, make it look more like the real scene of nature, or to achieve Color anti-counterfeit effect, improve the level of profitability of print function. All this is because the modern high-fidelity color printing technology is based on a computer as a platform. While applying previous experience, it also uses the latest research results of contemporary colorimetry.

With open and advanced tools, R&D personnel can evolve the color separation theory they have mastered into a practical color separation model for practical production. The use of different base color inks to design color separation models with different personalities and realize the printing and reproduction of unique color features is no longer a difficult task. The modern society has entered an era of advocating personalization. Personality attracts attention to a much higher degree than a simple, massively repetitive effect, because it shows courage and wisdom that is innovative. The wave of individuation of modern industrial products and services has become increasingly fierce because of the huge business opportunities. Printed products can realize the duplication of personalized colors, and will provide a more effective new platform for those outstanding advertising designers and forward-thinking print users to realize unique ideas and display corporate ideas. While helping them introduce themselves and their products to the society in a brand-new attitude, printing companies can also enjoy fame and fortune.

The high-fidelity color printing technology can realize the personalized color printing and copying function, and after the proper adjustment of the color separation model, it can also form a high-fidelity color anti-counterfeiting function. Anyone uses high-fidelity color anti-counterfeit printing technology to copy originals, and replicas can be easily and accurately identified. Each high-fidelity color anti-counterfeit technology solution includes a security color separation model and dozens of color passwords, each of which is different from each user.

The color password is determined by using the same metachromatic characteristics that the printing colors are the same and the overlapping dots can be different. In conventional four-color printing, because the basic color inks used are basically the same, the color separation model is basically the same, so regardless of the producers or the copy makers, the ink dots produced by a color separation are basically the same. Imitation products are difficult to accurately distinguish between visual effects and dot formation. A large number of fake and shoddy products are using the conventional four-color printing technology.

Compared with conventional four-color prints, high-fidelity color prints have a distinctive “one-line anti-counterfeiting” function that visually judges authenticity. Each color separation model used in high-fidelity anti-counterfeit prints is exclusively customized by users. Compared with other users' high-fidelity anti-counterfeiting technology solutions, the probability of repetition of color passwords is one tens of billionths, and therefore Really accurate quantitative detection of authenticity of "second-line anti-counterfeiting" function. The use of special inks is designed to increase the difficulty of imitation. In the design of anti-counterfeit products, the colors of the passwords can also be skillfully combined and designed into different patterns, or distributed in different parts, so that the copyists cannot easily perceive and analyze them. You can also use high-resolution printing of dot size and shape changes, network cable frequency combinations and other technologies to increase the technical characteristics of color passwords, which can increase the difficulty of imitation. In the current social situation in China, when the color effects of packaging prints have changed dramatically, which has a powerful role in promoting product sales, if there is also a reliable anti-counterfeiting function, this printing technology will undoubtedly have a huge market demand. Both print users and printing companies will gain considerable commercial benefits.

In the early stages of researching high-fidelity color printing technology, experts had a fierce debate over the possibility of neutral grays and the difficulty of control in practical applications for high-fidelity primary inks with more than three primary colors of CMY; high fidelity for the use of amplitude modulation networks. Whether multi-color printing will hit the net or not will cause great doubts. With the knowledge of experimental proof production and related theories, these are now standard technical specifications.

The key technologies of high-fidelity color separation technology include the digitization of ink color, the color gamut of ink printing, the color separation of color outside the color space, the decomposition of color components in the color, and neutral gray components. At present, technical principles such as the quantification of color printing and quality evaluation have become a topic of concern.

Technical principles on the quantification of printed colors

One of the outstanding problems is the feasibility of expressing the color of printing ink in RGB mode. The printing industry is accustomed to seeing RGB parameters as device-related, and the colors expressed in RGB are not determinable if they are separated from specific devices. Therefore, it is considered that the RGB parameter cannot be used to indicate the ink printing color. Whether RGB parameters can represent ink color as CIELAB chromaticity parameters, or under what conditions can be used as chromaticity parameters, clarifying these issues becomes the key to solving the problem.

The RGB color mode uses additive addition of three primary colors to produce different colors.

The CIE RGB spectral tristimulus value introduced by the International Commission on Illumination (CIE) first determines the wavelength and amount of light of the three primary colors, and then the isospectral spectrum color of each wavelength in the visible spectrum color can be expressed by a certain amount of RGB values. This includes the negative number of tristimulus values. These values ​​are called spectral tristimulus values, and all spectral tristimulus values ​​are called "standard chroma observers" (as shown in FIG. 22).

This experimental method and data is the quantitative basis of the modern CIE standard colorimetric system, and it is also the original basis for industrial color calibration, color measurement and calculation. In order to eliminate the inconvenience of using negative numbers, CIE later adopted an imaginary three-primary method to establish a new chromaticity diagram and normalize the three primary color values ​​of matched isospectral spectra, and called this method and data the CIE 1931 standard. The colorimetric system is the 1931 CIE XYZ system (shown in Figure 23).

The correspondence between color and chromaticity can be divided into two forms. One is the color value generated by a photoelectric conversion device such as a scanner and a digital camera, which is generally determined by the performance of a color filter or a CCD device. The electronic file of image color values ​​did not directly represent the correspondence between RGB parameters and CIELAB chromaticity. The other is image processing software represented by Photoshop. In recent years, the version has added the function of color RGB value and color space selection. The image electronic file may carry a profile parameter table conforming to the ICC standard. The main function of the parameter table is to specify the color space of the image color and the correspondence relationship with the chromaticity. Under this condition, any color represented in the RGB mode can be applied to the matrix operation and converted to the CIE XYZ color tristimulus value. The CIE XYZ color tristimulus values ​​have a definite conversion relationship with the CIELAB system. Therefore, for each RGB color value, the corresponding CIELAB colorimetric value can be obtained. In this sense, since RGB parameters have a unique chromaticity correspondence, they can be regarded as chromaticity parameter applications. RGB is related to devices in the traditional sense and has recently been developed to be related to the Profile parameter table. The significance of this kind of development is the same as the meaning of "first determining the wavelength and amount of light of the three primary colors" when the CIE RGB system was established. As a result, the RGB mode can be used more broadly in a defined printing color space, including printing colors that express primary inks, especially when implementing a broader color gamut than CMYK four colors. In fact, long ago, researchers used the RGB mode in addition to the CIE XYZ tristimulus value when calculating ink color using the Neugebauer equation.


Author: Houke Jie
Source: Digital Printing