Method for detecting printing color by using complex frequency spectrum color feature numerical values

Abstract

The invention discloses a method for detecting a printing color by using complex frequency spectrum color feature numerical values, comprising the following steps of: measuring the color of a printing matter through a visible spectrophotometer to obtain a spectrum function, and then calculating according to a complex frequency spectrum chromatic diagram and a color feature numerical value calculating method to obtain the complex frequency spectrum color feature numerical values such as a complex frequency spectrum color phase value H, a complex frequency spectrum brightness value L and the like; detecting a product color feature numerical value in real time in the printing and producing processes, and carrying out holographic detection and adjustment on the color and the contrast of the printing matter by utilizing the relation between brightness and the thickness of an ink layer, the relation between a color phase of a secondary color and color strength, the relation between gray level and the balance of three colors, i.e. yellow, pinkish red and green and the linear relation between comprehensive brightness and a dot area rate. Compared with the traditional detecting method, the method for detecting the printing color by using the complex frequency spectrum color feature numerical values has obvious advantages on the aspects such as data intuition, operability of method, effectiveness in use, economical efficiency of instruments, universality in popularization and the like, and particularly solves the problem that the two traditional indexes, i.e. three-color gray level balance and contrast linearization, are still judged mainly depending on vision and adjusted depending on experience.

Description

technical field [0001] The invention relates to a method for detecting and adjusting the color of printed matter, in particular to a method for detecting printing color by using complex spectrum color characteristic values. Background technique [0002] Modern printing has entered the era of full color. Accompanied by the high-quality requirements for printed products, there will inevitably be higher requirements for the detection and control of the color of printed products in the printing production process. The limitations of the existing printing color measurement and control methods are mainly: [0003] 1) Manual visual inspection method [0004] In the early printing process, visual inspection was commonly used to judge whether the color of the printed matter was consistent with the original manuscript. For printed matter with higher brightness value and lower chroma value, the visual effect is better. For prints with moderate brightness and high chroma, visual ins...

AI Technical Summary

Problems solved by technology

Although the above methods can judge the effect of gray balance, the solution cannot be given only by relying on the S value, that is, how to adjust the respective ink supply volumes of CMYK to achieve gray balance cannot be clearly given.

[0020] 5) Relative contrast

Therefore, the K value is suitable for printing process research, but in the printing production process, the K value can only be used as a reference, and the operability is poor

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