Method for optimizing identification grating extraction performance in information extraction phase

Abstract

The invention discloses a grating anti-fake method for improving identification grating extraction performance. The method comprises the following steps of S1, selecting a host image, specifically, decomposing the host image, thereby enabling the host image to be composed of four color channels of a channel C, a channel M, a channel Y and a channel K; setting a hiding area of anti-fake informationon at least one color channel of the host image, and recording the color channel on which the hiding area is located as a master mask, wherein color values of all pixels in the hiding area on the master mask are alpha, and the alpha is 0.1-0.5; recording the rest color channels as three secondary masks, and reselecting the host image when the hiding area of which alpha is 0.1-0.5 cannot be selected; S2, halftoning the host image; and S3 hiding the anti-fake information. According to the method, the stealthiness and extraction effect of the anti-fake information are improved.

Description

technical field [0001] The invention belongs to the technical field of grating anti-counterfeiting, and in particular relates to a method for identifying the extraction performance of gratings in the information extraction stage of an optimization method. Background technique [0002] The limit resolution capability of normal vision of the human eye is limited. When the dot size and dot spacing of the digitally screened image are smaller than the limit resolution capability of the human eye, the human eye cannot distinguish the dots. Therefore, the discretized binary image is actually discontinuous, but due to the visual characteristics of the human eye, if viewed from a certain viewing distance, the dots cannot be distinguished at all, that is, the details of the image cannot be distinguished, and finally it gives a continuous tone. Image effect, so as to realize the printing reproduction of continuous tone originals. [0003] Grating anti-counterfeiting is an anti-counter...

AI Technical Summary

Problems solved by technology

[0007] 1. There is a far-reaching technical bias in the principle of optimal outlets: Existing studies all believe that the displacement setting of outlets must meet the principle of optimal outlets. Only when the outlets that make up the anti-counterfeiting information are at the optimal location, when the digital grating detects the anti-counterfeiting information, The reproduction of anti-counterfeiting information is the most obvious and clear, but there has been a habitual technical bias in the prior art for many years, and it is believed that the best point is only to move D / 2 along the direction of the screen angle or the direction perpendicular to the screen angle, resulting in theoretical Guidance angle The angle and distance that can be adjusted by the net point are very limited;

[0008] 2. The research on the overlap of dots is not in place: In order to realize the moiré effect, all the dots in the dot selection area are considered to be displaced in the same way. The displacement direction is along the direction of the screen angle or the direction perpendicular to the screen angle. The displacement distance It is D / 2, that is, in the existing method, the dots of all color values ​​(dot percentage) are generalized, and there is no pertinence; at the same time, since the screening parameters will be set in the early halftone processing, the number of screen lines is a known number , the number of screen lines determines D and the side length D of a single screen adjustment unit 2 , D=D 2 , therefore, D / 2 is a fixed value; however, for some of the dots located on the boundary of the dot selection area, the actual movable distance is the distance between the closest points of the two dots, which is recorded as D 1 , with the increase of dot percentage, D 1 will gradually decrease, therefore, D 1 is a variable; when D 1 When it is less than D / 2, if the phase modulation is still carried out according to the method of the prior art, it will cause overlapping between the network points on the boundary, cause strong visual perception, and make the anti-counterfeiting invalid. The actual distance between the network points has not been considered in the prior art Synergistic impact on stealth and extraction performance

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