Embedding method for raster anti-counterfeiting invisible image-text based on digital screening

An invisible graphic and grating technology, applied in the field of image processing, can solve the problems such as the inability to obtain a good concealment effect in the middle tone or dark tone, the irregular shape of the dots, the inability to apply the phase modulation method, etc. The effect of hidden performance, good display effect

Inactive Publication Date: 2018-12-04
HEFEI SIBOT SOFTWARE DEV CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] (2) The dot percentage limits the practical application of the algorithm formula: the phase modulation method considers the displacement between circular dots, but as the percentage of dots increases, the actual shape of dots in the halftone adjustment unit is not circular shape, especially when the midtone or dark tone image is used as the source image, according to the growth model method, the dot shape is irregular, and the phase modulation method cannot be applied at all. Therefore, in the existing literature research, neither the midtone nor the dark tone can be used. achieve better concealment

Method used

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  • Embedding method for raster anti-counterfeiting invisible image-text based on digital screening
  • Embedding method for raster anti-counterfeiting invisible image-text based on digital screening
  • Embedding method for raster anti-counterfeiting invisible image-text based on digital screening

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0073] see figure 1 , a kind of embedding method of grating anti-counterfeit invisible graphic based on digital screen, comprises the following steps:

[0074] Step 1. Prepare the source image;

[0075] see figure 2 , figure 2 The source image in the form of a digital file prepared for the source image is composed of four color plates of C, M, Y, and K;

[0076] Step 2. Pre-processing

[0077] 1. Select an encrypted color version

[0078] Set hidden conditions, and select at least one color plate that matches the hidden conditions as an encrypted color plate;

[0079] The aforementioned hidden conditions include color value conditions and histogram conditions. In this embodiment, the selection of encrypted color plates adopts the method of combining analysis of color values ​​and histograms, specifically:

[0080] (1), analyze the color value

[0081] The source image includes x×y pixels; read the color values ​​on the four color plates respectively. The method of rea...

Embodiment 2

[0107] see Figure 6-9, on the basis of embodiment 1, the difference of embodiment 2 is:

[0108] (1), the source image is different from the invisible image and text;

[0109] (2), encrypted color version is M color version (i.e. product version), in the present embodiment Unit is%.

[0110] (3) The simulated grating is a dot grating, which is made up of uniformly arranged dots with the same diameter, and the distance between each dot is Note the diameter R of each dot, the calculation method of R is:

[0111]

[0112] In this embodiment, preferably

Embodiment 3

[0114] see Figures 10-13 , on the basis of embodiment 1, the difference of embodiment 3 is:

[0115] (1), the source image is different from the invisible image and text;

[0116] (2), in this embodiment Unit is%.

[0117] Using the area contrast function F i and information entropy function algorithm T i Respectively evaluate the analog grating of embodiment 1, 2 and 3 and the overlay of the halftone image of the source image carrying invisible graphics (under the state of accurately extracting hidden graphics), the results obtained are shown in Table 1 below:

[0118] Table 1 Evaluation of invisible graphics and text display effect

[0119]

[0120] f i and T i The closer the value of is to 1, the better the effect of invisible graphics and text is, and the regional contrast function F i The algorithm is as follows:

[0121]

[0122]

[0123] The above formula is an image saliency evaluation function based on regional contrast, dev(x, y) represents the re...

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Abstract

The invention discloses an embedding method for a raster anti-counterfeiting invisible image-text based on digital screening. The method comprises the following steps: step 1, preparing a source image; step 2, performing preprocessing; step 3, setting a latent image; step 4, performing plate making and outputting. The invention analyzes shortcomings of a phase modulation method, and a fifty-fiftyinverse method is used to generate dots for 50-90% of color values in a digital screening process. With 50% of the dots as reference, for dots higher than 50%, a point pattern of a small dot which iscomplementary to the dots, and a negation operation rule is used to obtain the dots. The method breaks technical bias in a phase modulation method, and the improved phase modulation method can also beused for images in midtone and dark tone. In particular, concealment of invisible images-texts of a dark tone image has made very remarkable progress.

Description

technical field [0001] The invention belongs to the technical field of image processing, and in particular relates to a digital screen-based embedding method of grating anti-counterfeit invisible graphics. Background technique [0002] With the continuous development of printing technology, some pirates have also begun to obtain illegal benefits by imitating or duplicating various printed materials. Although new technologies such as paper anti-counterfeiting, ink anti-counterfeiting, pattern anti-counterfeiting, and 3D anti-counterfeiting are emerging, most of them are based on increasing costs. cost. The anti-counterfeiting method based on the combination of digital screen technology and grating material characteristics is simple and easy, does not have too high requirements for equipment and printing technology, and will not increase production costs. It is a promising anti-counterfeiting method. Its main points It is the hiding and displaying of invisible graphics. The h...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F21/16G06F21/60G06T5/40G06T7/90
CPCG06F21/16G06F21/602G06T5/40G06T7/90
Inventor 吴青明
Owner HEFEI SIBOT SOFTWARE DEV CO LTD
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