Grating anti-counterfeiting method for improving identification grating extraction performance

Abstract

The invention discloses a grating anti-counterfeiting method for improving identification grating extraction performance. The method comprises the following steps: step 1: selecting a host image: decomposing the host image, so that the host image is composed of four color channels in total, namely, a C channel, an M channel, a Y channel and a K channel, wherein at least one color channel of the host image has a hidden area where anti-counterfeiting information can be set, the color channel where the hidden area is located is a master mask, the color value of all pixel points of the hidden areaon the mother set is alpha, alpha is 0.1 to 0.5, the remaining color channels are 3 slave masks, and when the hidden area in which the alpha is 0.1 to 0.5 cannot be selected, the host image is re-selected; step 2, performing halftone processing on the host image; and step 3, hiding the anti-counterfeiting information. By adoption of the grating anti-counterfeiting method disclosed by the invention, the concealment and extraction effect of the anti-counterfeiting information are improved.

Description

Technical field [0001] The invention belongs to the technical field of grating anti-counterfeiting, and in particular relates to a grating anti-counterfeiting method for improving the extraction performance of a recognition grating. Background technique [0002] The limit resolving power of normal vision of the human eye is limited. When the dot size and dot pitch of the digitally screened image are smaller than the limit resolving power of human vision, the human eye cannot distinguish the dots. So in fact, the discrete binary image is not continuous, but due to the visual characteristics of the human eye, if you look at it at a certain observation distance, you can’t distinguish the dots at all, that is, you cannot distinguish the details of the image, and finally give people a continuous tone Image effect, so as to realize the printing and copying of the original manuscript continuously. [0003] Raster anti-counterfeiting is an anti-counterfeiting technology produced by the co...

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 dots located on the border 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 concealment and extraction performance

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