About the quality inspection principles of high fidelity printing products in the 1970s, CIE recommended two approximately uniform color spaces and corresponding colors. Our company's universal testing machine now mainly has two series difference formulas, namely, the electronic universal testing machine and the hydraulic universal testing machine, namely CIE LAB and CIEluv. L, a and B in CIE LAB color space are transformed from X, y and Z in CIE XYZ color space by nonlinear cubic root function. CIE LAB color space belongs to psychological color space, which can be explained by the principle of Herring's four color opposition theory. In the A and B two-dimensional coordinate system of CIE LAB color space, ＋ a represents red, － a represents green, ＋ B represents yellow and － B represents blue. The lightness of a color is expressed as a percentage of L. Foreign experts used 555 pairs of color samples to evaluate the relationship between △ E in lab color space and visual results, and found that CIE LAB system is 0.72, which is the closest to calculating color difference and visual perception in all color spaces at present, and is also very close to the degree of goodness of hardness modification experiment of constant hue trajectory and constant chromaticity trajectory in Munsell color card in a and B two-dimensional coordinate system. At present, dye, pigment, ink and other color industry departments are the first to choose CIE LAB color space. The printing technology research and production departments at home and abroad also began to use this space as a color matching and evaluation method for printing color
China has formulated relevant technical standards for the application of chromaticity measurement techniques and methods. It is stated in the standard that the purpose of colorimetric measurement is to provide the instrument response simulating the standard observer as much as possible. In printing, chromaticity measurement is mainly used for color matching and the establishment of color standards. The standard specifies the technical requirements for the use of colorimeter measurement and measurement data calculation for the substrate, ink color, tone value and color difference of CMYK four-color printing. At present, the standard has not directly stipulated the relevant technical requirements that the primary color ink exceeds the high fidelity color printing of CMYK, nor has it stipulated the step value control index of amplitude modulation above 250lpi and frequency modulation
Beijing jiayitianshi Electronic Technology Co., Ltd., a domestic research unit of high-definition and high fidelity color printing technology, cooperated with experts and users to establish technical methods related to high-definition and high fidelity color printing process control and finished product quality inspection based on CIE LAB system. The brief introduction is as follows:
this technology has been successfully applied to the iron printing industry - Hangzhou COFCO Meite container Co., Ltd., which has significantly improved the product quality, expanded the application scope of the product, improved the added value and market competitiveness of the product, and has good economic benefits and promotion value. Compared with the conventional four-color 175lpi printing products, the product produced by this technology has significantly improved the image clarity and the fine level, and the visual roughness caused by Rose spots after overprint is significantly reduced. The printing color gamut is significantly increased, the printing colors are brighter and more saturated, the layers are richer, and the three-dimensional sense is stronger. Under certain conditions, reducing the use of spot color ink has a certain anti-counterfeiting effect under the technical level of the iron printing industry. "
high fidelity color printing process control and finished product quality inspection technical methods mainly evaluate the characteristics of base color ink in CIE LAB color space, measure and display the printing gamut range of high fidelity ink, color separation printing gamut range, printing color scale characteristics, neutral gray balance characteristics, etc., and use the simulated lab three-dimensional coordinate effect to comprehensively analyze the hue angle, color saturation and color brightness of printing color. Through the application of the above technical methods, further add the calibration method of concrete pressure testing machine: deeply understand the principle of high fidelity printing, grasp the key control indicators, and gradually improve the ability to independently design color separation models, especially the setting and use level of anti-counterfeiting color codes of color anti-counterfeiting models. Printing enterprises can select the most cost-effective technical solutions to produce new products according to the needs of originals or users. Due to the use of chromaticity measurement and control technology, technicians can further improve their understanding of the nature of color printing reproduction, which will have a continuous impact on improving the technical management level and R & D capability of enterprises屁多腹胀是什么原因造成的