CN111597516A - Document anti-copying method and system based on secret mark watermark - Google Patents
Document anti-copying method and system based on secret mark watermark Download PDFInfo
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F21/00—Security arrangements for protecting computers, components thereof, programs or data against unauthorised activity
- G06F21/10—Protecting distributed programs or content, e.g. vending or licensing of copyrighted material ; Digital rights management [DRM]
- G06F21/16—Program or content traceability, e.g. by watermarking
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0021—Image watermarking
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- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2201/00—General purpose image data processing
- G06T2201/005—Image watermarking
- G06T2201/0064—Image watermarking for copy protection or copy management, e.g. CGMS, copy only once, one-time copy
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Abstract
The invention provides a document anti-copying method and a document anti-copying system based on a secret mark watermark. The specific method comprises the following steps: step 1, obtaining printing characteristics, and searching the range of the gray values of the watermark of the four channels of the printer by using a chromatogram; step 2, printing any pattern after adjusting the gray value range of the corresponding channel to form a secret mark watermark; and 3, judging whether the document is a copied document or not by observing the state of the secret mark watermark. The invention aims to conveniently, quickly and accurately distinguish the duplicate, the dark watermark with set gray value is added in the original document, so that the dark watermark disappears after the original document is copied, and people can distinguish the original document from the duplicate document by detecting whether the dark watermark exists or not. The invention does not need to adopt special paper or special ink for printing, saves cost and can help people to quickly distinguish original edition documents from copied edition documents.
Description
Technical Field
The invention relates to a document anti-copying method, in particular to a document anti-copying method based on a secret mark watermark.
Background
At present, the more convenient the original copied document is, the higher the fineness is, and the more difficult the original document and the copied document are to be distinguished. At present, a common method is to use special paper or print with special ink to help people to quickly distinguish original documents from copied documents, but the method increases the use cost and even needs special printing equipment to cooperate, so that the use range is limited.
Disclosure of Invention
The purpose of the invention is as follows: the document anti-copying method based on the secret mark watermark is provided to solve the defects in the prior art. It is a further object to provide a system for carrying out the above method.
The technical scheme is as follows: a document anti-copying method based on a secret mark watermark comprises the following steps:
step 1, obtaining printing characteristics, and searching the range of the gray values of the watermark of the four channels of the printer by using a chromatogram;
step 2, printing any pattern after adjusting the gray value range of the corresponding channel to form a secret mark watermark;
and 3, judging whether the document is a copied document or not by observing the state of the secret mark watermark.
In a further embodiment, the step 1 further comprises:
step 1-1, generating a standard chromatogram electronic diagram: generating 256 gray blocks with gray values from 1 to 256 gray values by using software, wherein the gray value 1 is the lightest, and the gray value 256 is the deepest;
step 1-2, printing a standard chromatogram: respectively printing gray blocks of the standard chromatogram by using four color channels of a printer CMYK to respectively obtain chromatograms of the four color channels of CMYK;
step 1-3, respectively observing gray blocks of four color areas of CMYK, respectively searching color blocks with the lowest macroscopic gray in the four color areas, wherein the gray value of the color blocks in the original standard chromatogram is the lower limit of the gray value range of a preset secret mark pattern in four color channels of CMYK;
step 1-4, scanning the printed chromatogram to obtain a scanned chromatogram electronic map, and respectively searching color blocks with gray values larger than 1 and the smallest gray values in four color channels of CMYK, wherein the gray values of the color blocks in the original standard chromatogram are the upper limits of the gray value ranges of the preset secret mark patterns in the four color channels of CMYK;
step 1-5, combined with steps 1-1 through 1-4, yields the lower and upper limits of the gray scale value range for the proper printer device for the four color channels C, M, Y, K, respectively.
In a further embodiment, the step 2 further comprises: calculating the absolute value of the difference between the upper limit and the lower limit of the gray value range of the CMYK four color channels, taking the color channel with the largest absolute value as the optimal channel for generating the secret mark watermark, and sequencing the other channels from large to small according to the absolute value of the difference between the upper limit and the lower limit of the color channel, and sequentially using the channels as alternative channels; and correcting the gray value of the pattern to be selected according to the upper and lower limits of the gray value of the selected channel to obtain the watermark on the channel.
In a further embodiment, the step 3 further comprises: when the original print is scanned or copied, the generated watermark in the preset color channel from step 1 to step 2 disappears or is weak, so that the visual characteristic, the coding content or the watermark strength of the watermark are changed, and the fact that the print is the original or the copied print is inferred.
In a further embodiment, the default paper color is white, if the paper is other colors, step 1 needs to be repeated on the paper, the gray value range of each color channel of the secret mark generated on the paper by the printer is obtained and stored in the secret mark generation software, and when the secret mark pattern is generated on the paper with the color, the electronic map of the secret mark pattern is adjusted according to the gray parameter.
In a further embodiment, the secret watermark pattern is one or more of characters, patterns and patterns, and the added secret watermark is fixed or variable for different documents.
An optimal method for calculating the gray value of the watermark for correcting the pattern to be selected can be according to the formula:
w0 is the gray value of each pixel of the pattern to be selected, b is the upper limit of the gray value of the channel to be selected, a is the lower limit of the gray value of the channel to be selected, W is the gray value of each pixel of the modified watermark, and | x | represents the rounding of the discarded decimal part of the logarithm value.
A document anti-copying system based on a secret mark watermark is characterized by comprising a gray value monitoring module, a data processing module and a data processing module, wherein the gray value monitoring module is used for acquiring the gray value range of the secret mark watermark of a printer; the channel selection module is used for selecting a preset color channel according to the gray value range; and a secret mark watermarking processing module for making the secret mark watermarking pattern according to the selected color channel.
In a further embodiment, the gray value calculation module is further configured to print a standard chromatogram to obtain a printing characteristic of a printer, scan or copy the printed standard chromatogram by using a standard scanner, and calculate a gray value range of a preset secret mark pattern according to a comparison between a previous image and a next image;
the channel selection module is further used for calculating the absolute value of the difference between the upper limit and the lower limit of the gray value range of the CMYK four color channels, and the color channel with the maximum absolute value is used as the optimal channel scheme for manufacturing the secret mark watermark pattern; sequencing the rest gray value ranges from large to small according to the absolute value of the difference between the upper limit and the lower limit of the gray value ranges, and sequentially adopting an alternative channel scheme;
the said secret mark watermark processing module further generates one or more secret mark patterns including characters, patterns and figures in the secret mark watermark channel obtained by the channel selecting module.
In a further embodiment, the gray value monitoring module further generates 256 gray blocks with gray values from 1 to 256, wherein the gray value 1 is the lightest and the gray value 256 is the deepest; respectively printing gray blocks of the standard chromatogram by using four color channels of a printer CMYK to respectively obtain chromatograms of the four color channels of CMYK; monitoring gray blocks of four color areas of CMYK respectively, and searching color blocks with the lowest macroscopic gray in the four color areas respectively, wherein the gray value of the color blocks in an original standard chromatogram is the lower limit of the gray value range of a preset secret mark pattern in four color channels of CMYK; scanning the printed chromatogram to obtain a scanned chromatogram electronic map, and respectively searching color blocks with gray values larger than 1 and the smallest gray value in the four CMYK color channels, wherein the gray values of the color blocks in the original standard chromatogram are the upper limit of the gray value range of the preset secret mark pattern in the four CMYK color channels; the lower and upper limits of the gray scale value ranges in the C, M, Y, K four color channels, respectively, of the hologram pattern appropriate for the printing apparatus are finally obtained.
Has the advantages that: the invention provides a document anti-copying method and a document anti-copying system based on a secret mark, which are convenient, rapid and accurate to distinguish a copy, the secret mark with a set gray value is added in an original document, so that the secret mark disappears after the original document is copied, and people distinguish an original document from a copy document by detecting whether the secret mark exists or not. The invention does not need to adopt special paper or special ink for printing, saves cost and can help people to quickly distinguish original edition documents from copied edition documents.
Drawings
FIG. 1 is a flow chart of the present invention.
Fig. 2 is a specific flowchart of finding the range of the gray scale values of the watermark for four channels of the printer by using the chromatogram in the present invention.
Detailed Description
At present, the more convenient the original copy document is, the higher and more high fineness leads to distinguishing original edition document and copy edition document more and more difficult, for this reason, this patent proposes a secret mark watermark scheme, convenient quick accurate the distinguishing copy, through adding the secret mark watermark of setting for grey scale value in original document for after original document is duplicated, this secret mark watermark disappears, people have the secret mark watermark through detecting, distinguish original edition document and copy edition document.
The electronic scanning and copying device has different reproduction degrees for scanning and copying different colors, for example, the reproduction degree of black is the highest, and then red and yellow are carried out in sequence, and the reproduction degree of the lowest is blue. By utilizing the characteristic, the shading secret mark (watermark) with the gray level within a certain range can be artificially generated, and the secret mark disappears or is weak after the positive printing is scanned or copied, so that the visual characteristic, the coding content, the watermark strength and the like of the secret mark are obviously changed, and the positive printing or the copied printing is deduced.
The technical scheme of the invention is further explained by the embodiment and the corresponding attached drawings.
In the printing stage, the printing characteristic of the printer is obtained by printing the standard chromatogram, then the printed standard chromatogram is scanned or copied by the standard scanner, the preset gray value range of the secret mark pattern is calculated according to the comparison of the front graph and the back graph, and the secret mark generation software generates the secret mark pattern in the obtained gray value range.
Through a number of experiments, we have obtained the range of gray values for the major brands of printers currently on the market, tabulated below:
TABLE 1 Gray scale Range for part of the printer CMYK channels (lower-upper bound)
| Printer brand | C channel range | M channel range | Range of Y channel | Range of K channels |
| Kemei C458 | 6-60 | 3-30 | 4-40 | 2-20 |
| Hewlett packard M750 | 5-55 | 3-27 | 4-36 | 2-18 |
| Canon WG7850 | 6-65 | 4-32 | 5-44 | 3-22 |
| Epson WF-C869 | 5-60 | 4-35 | 5-45 | 3-25 |
| Shile 7800 | 6-57 | 3-28 | 4-40 | 2-22 |
| Reason light DD5450C | 6-70 | 4-35 | 5-45 | 3-24 |
From the above data, the blue channel is preferred to produce the dark watermark pattern because the gray scale has the widest application range.
The specific calculation method comprises the following steps:
(1) and generating a standard chromatogram electronic map. With software, 256 gray blocks (1 lightest 256 deepest) with gray values from 1 to 256 gray were generated.
(2) And printing a standard chromatogram. And respectively printing the gray blocks of the standard chromatogram by using four color channels CMYK of the printer to respectively obtain the chromatograms of the four color channels CMYK.
(3) And respectively observing gray blocks of the four color areas CMYK, respectively searching the color block with the lowest macroscopic gray level in the four color areas, wherein the gray level of the color blocks in the original standard chromatogram is the lower limit of the gray level range of the preset secret mark pattern in the four color channels CMYK.
(4) And scanning the printed chromatogram to obtain a scanned chromatogram electronic map, and respectively searching color blocks with gray values larger than 1 and the minimum gray value in the CMYK four color channels, wherein the gray values of the color blocks in the original standard chromatogram are the upper limit of the gray value range of the preset secret mark pattern in the CMYK four color channels.
(5) To this end, the lower limit and the upper limit of the gray value range in C, M, Y, K four color channels, respectively, of the hologram pattern suitable for the printing apparatus were obtained.
The default paper color is white, if the paper is other colors, the test process needs to be repeated on the paper, the gray value range of each color channel of the secret mark generated on the paper by the printer is obtained and stored in the secret mark generation software, and when the secret mark pattern is generated on the paper with the color subsequently, the electronic image of the secret mark pattern is adjusted according to the gray parameter.
As noted above, while the present invention has been shown and described with reference to certain preferred embodiments, it is not to be construed as limited thereto. Various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (10)
1. A document anti-copying method based on a secret mark watermark is characterized by comprising the following steps:
step 1, obtaining printing characteristics, and searching the range of the gray values of the watermark of the four channels of the printer by using a chromatogram;
step 2, printing any pattern after adjusting the gray value range of the corresponding channel to form a secret mark watermark;
and 3, judging whether the document is a copied document or not by observing the state of the secret mark watermark.
2. The method of claim 1, wherein the step 1 further comprises:
step 1-1, generating a standard chromatogram electronic diagram: generating 256 gray blocks with gray values from 1 to 256 gray values by using software, wherein the gray value 1 is the lightest, and the gray value 256 is the deepest;
step 1-2, printing a standard chromatogram: respectively printing gray blocks of the standard chromatogram by using four color channels of a printer CMYK to respectively obtain chromatograms of the four color channels of CMYK;
step 1-3, respectively observing gray blocks of four color areas of CMYK, respectively searching color blocks with the lowest macroscopic gray in the four color areas, wherein the gray value of the color blocks in the original standard chromatogram is the lower limit of the gray value range of a preset secret mark pattern in four color channels of CMYK;
step 1-4, scanning the printed chromatogram to obtain a scanned chromatogram electronic map, and respectively searching color blocks with gray values larger than 1 and the smallest gray values in four color channels of CMYK, wherein the gray values of the color blocks in the original standard chromatogram are the upper limits of the gray value ranges of the preset secret mark patterns in the four color channels of CMYK;
step 1-5, combined with steps 1-1 through 1-4, yields the lower and upper limits of the gray scale value range for the proper printer device for the four color channels C, M, Y, K, respectively.
3. The method of claim 2, wherein the step 2 further comprises: calculating the absolute value of the difference between the upper limit and the lower limit of the gray value range of the CMYK four color channels, taking the color channel with the largest absolute value as the optimal channel for generating the secret mark watermark, and sequencing the other channels from large to small according to the absolute value of the difference between the upper limit and the lower limit of the color channel, and sequentially using the channels as alternative channels; and correcting the gray value of the pattern to be selected according to the upper and lower limits of the gray value of the selected channel to obtain the watermark on the channel.
4. The method of claim 1, wherein the step 3 further comprises: when the original print is scanned or copied, the generated watermark in the preset color channel from step 1 to step 2 disappears or is weak, so that the visual characteristic, the coding content or the watermark strength of the watermark are changed, and the fact that the print is the original or the copied print is inferred.
5. A method of claim 1 for preventing copying of a document based on a steganographic watermark, wherein: and (3) the default color of the paper is white, if the paper is other colors, the step (1) needs to be repeated on the paper, the gray value range of each color channel of the secret mark generated on the paper by the printer is obtained and stored in the secret mark generation software, and when the secret mark pattern is generated on the paper with the color, the electronic image of the secret mark pattern is adjusted according to the gray parameter.
6. A method of claim 1 for preventing copying of a document based on a steganographic watermark, wherein: the said secret mark watermark pattern is one or more of characters, patterns and decorative patterns, and the added secret mark watermark is fixed or variable for different documents.
7. A method of claim 1 for preventing copying of a document based on a steganographic watermark, wherein: the preferred method for calculating the gray value of the watermark for correcting the pattern to be selected can be according to the formula:
whereinW0Is the gray value of each pixel point of the pattern to be selected,bis the upper limit of the gray value of the channel to be selected,ais the lower limit of the gray value of the channel to be selected,Wto correct the gray value of each pixel of the watermark,|*|indicating that the value is rounded by the fraction discarded.
8. A document anti-copying method based on a secret mark watermark is characterized by comprising the following modules:
the gray value monitoring module is used for acquiring the gray value range of the printer secret mark watermark;
the channel selection module is used for selecting a preset color channel according to the gray value range;
and the secret mark watermarking processing module is used for manufacturing the secret mark watermarking pattern according to the selected color channel.
9. A method of claim 8 for preventing copying of a document based on a steganographic watermark, wherein: the gray value calculation module is further used for printing the standard chromatogram to obtain the printing characteristics of the printer, scanning or copying the printed standard chromatogram through a standard scanner, and calculating the gray value range of the preset secret mark pattern according to the comparison of the front graph and the rear graph;
the channel selection module is further used for calculating the absolute value of the difference between the upper limit and the lower limit of the gray value range of the CMYK four color channels, and the color channel with the maximum absolute value is used as the optimal channel scheme for manufacturing the secret mark watermark pattern; sequencing the rest gray value ranges from large to small according to the absolute value of the difference between the upper limit and the lower limit of the gray value ranges, and sequentially adopting an alternative channel scheme;
the said secret mark watermark processing module further generates one or more secret mark patterns including characters, patterns and figures in the secret mark watermark channel obtained by the channel selecting module.
10. A method of preventing copying of a document based on a steganographic watermark as recited in claim 9, wherein:
the gray value monitoring module further generates 256 gray blocks with gray values from 1 to 256, wherein the gray value 1 is the lightest gray value and the gray value 256 is the deepest gray value; respectively printing gray blocks of the standard chromatogram by using four color channels of a printer CMYK to respectively obtain chromatograms of the four color channels of CMYK; monitoring gray blocks of four color areas of CMYK respectively, and searching color blocks with the lowest macroscopic gray in the four color areas respectively, wherein the gray value of the color blocks in an original standard chromatogram is the lower limit of the gray value range of a preset secret mark pattern in four color channels of CMYK; scanning the printed chromatogram to obtain a scanned chromatogram electronic map, and respectively searching color blocks with gray values larger than 1 and the smallest gray value in the four CMYK color channels, wherein the gray values of the color blocks in the original standard chromatogram are the upper limit of the gray value range of the preset secret mark pattern in the four CMYK color channels; the lower and upper limits of the gray scale value ranges in the C, M, Y, K four color channels, respectively, of the hologram pattern appropriate for the printing apparatus are finally obtained.
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| CN115139670A (en) * | 2022-07-08 | 2022-10-04 | 广东阿诺捷喷墨科技有限公司 | Inkjet printing method and system based on single pass inkjet data processing |
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| CN1709709A (en) * | 2005-06-13 | 2005-12-21 | 北京北大方正电子有限公司 | Printing method of security file inlaid with anti-copying back-lines |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113835647A (en) * | 2021-09-27 | 2021-12-24 | 吉林省吉时宇飞电子信息工程有限责任公司 | Method for realizing anti-copying readable dot matrix graphic digital watermark |
| CN115139670A (en) * | 2022-07-08 | 2022-10-04 | 广东阿诺捷喷墨科技有限公司 | Inkjet printing method and system based on single pass inkjet data processing |
| CN115139670B (en) * | 2022-07-08 | 2024-01-30 | 广东阿诺捷喷墨科技有限公司 | Inkjet printing method and system based on single pass inkjet data processing |
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