CN103295184A - Frequency domain and airspace combined halftone watermarking method - Google Patents
Frequency domain and airspace combined halftone watermarking method Download PDFInfo
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- CN103295184A CN103295184A CN2013101921235A CN201310192123A CN103295184A CN 103295184 A CN103295184 A CN 103295184A CN 2013101921235 A CN2013101921235 A CN 2013101921235A CN 201310192123 A CN201310192123 A CN 201310192123A CN 103295184 A CN103295184 A CN 103295184A
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Abstract
The invention discloses a frequency domain and airspace combined halftone watermarking method. The frequency domain and airspace combined halftone watermarking method includes steps of (1) extracting characteristic images; (2) preprocessing watermarked images; (3) preprocessing watermark embedding; (4) acquiring a characteristic matrix of embedded watermarks; (5) acquiring blocked halftone images; (6) embedding the watermarks; (7) searching to obtain the optimum halftone image; (8) correcting the image; (9) acquiring watermark-contained discrete cosine transform coefficient; (10) extracting the watermarks. The frequency domain and airspace combined halftone watermarking method solves the problems that image binarization processing is required during extracting the watermarks by an airspace halftone watermarking method, the images embedded with the watermarks are poor in visual effect, and the watermarks are weak in resistance to printing-scanning impact. The frequency domain and airspace combined halftone watermarking method has the advantages of strong robustness to impacts of printing-scanning, random obliteration and cutting and the like and good visual effect of the images, and embedding capacity of the watermarks is greatly increased.
Description
Technical field
The invention belongs to technical field of image processing, further relate to the half water transfer impression method that a kind of frequency domain in the Information Hiding Techniques field and spatial domain combine.When the present invention is used in printing/printing output image, with the watermark information embedded images, and extract the watermark information that embeds by the image behind the scanning and printing, realize to print, the copyright protection of printed matter.
Background technology
In recent years, in many printings and publish using, the fake and forged behavior that is becoming increasingly rampant gave and printed/and printing export false proof brought new challenge.Digital watermark technology is extensive use of both at home and abroad as the technical measures of digital product copyright protection.Watermark at printed matters such as printout, books, magazines is the halftone image watermark.Half water transfer impression method of robust mainly is divided into two classes: the method that spatial domain method, frequency domain and spatial domain combine.
The patent of Xian Electronics Science and Technology University's application " based on half water transfer impression method of block of pixels parity check sum piece error dispersion " (application number: 201210434246.0, application publication number: CN102930497A) disclose a kind of half water transfer impression method that disperses based on block of pixels parity check sum piece error.This method proposed a kind of with block of pixels as processing unit, and introduced the local binary pattern of reaction partial structurtes features, embed watermark when image half is transferred has a stronger robustness.But this method still has the following disadvantages, because this method is that visual effect is bad at the spatial domain embed watermark.In addition, the spatial domain algorithm that this method adopts is relatively poor to synchronous resistivity, and under the undesirable situation of synchronous correction, watermark extracting can be failed.
People such as Jing-Ming G are at " Watermarking in halftone images with parity-matched error diffusion " (" Signal Processing " 2011,91:126-135) a kind of indirect embedding inlay technique is proposed, this method is based on the statistical property in zone, when image being carried out half accent, come embed watermark by adding noise, improved the robustness of watermark to a certain extent, but, this method still has the following disadvantages, owing to this method statistical property based on the zone when extracting watermark, depend on pixel value and quantization threshold, pixel value is being printed-scanning front and back instability, and work as printer, scanner models is not simultaneously, threshold value is selected difficulty, has therefore influenced the robustness of extracting watermark.
People such as S.C.Pei are at " Joint halftoning and watermarking " (IEEE Transaction on Signal Process.51, (4) proposing a kind of while (2003) 1054-1068) partly is in harmonious proportion the method for water mark inlaying, this method is introduced half water transfer seal field with spread spectrum, the water mark inlaying image visual effect that obtains is good, and common image attack, printing-scanning is had stronger robustness.But, still the having the following disadvantages of this method, the method complexity of partly changing the line map and the operand of searching for initial water mark inlaying are very big; Watermark requires known original continuous tone images; Watermark is the sequence of obeying standardized normal distribution, and that can only represent watermark has or do not have, and has only embedded 1 watermark in essence, and therefore, the watermark embedded quantity of this method is low.
Summary of the invention
The purpose of this invention is to provide the half water transfer impression method that a kind of frequency domain and spatial domain combine, mainly printing/printing in the printing/printed works embed watermark, for copyright protection provides foundation.The subject matter that the present invention will solve be the existing half water transfer impression method parameter that combines based on frequency domain and spatial domain more, realize complicatedly, the watermark embedded quantity is low, especially needs the non-blind watermark problem of continuous-tone image when extracting watermark.
The present invention includes two processes of watermark embedding and watermark extracting;
The concrete steps of watermark embed process of the present invention are:
(1) extract characteristic image:
1a) carrier image is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain block image;
1b) to each piecemeal average according to from left to right, from top to bottom order forms
The eigenmatrix of size, wherein P, Q represent width and the height value of carrier image respectively.
(2) watermarking images pre-service:
The binary bitmap matrix is carried out the Arnold scramble, obtain the watermarking images matrix behind the scramble.
(3) watermark embeds preprocessing process:
3a) eigenmatrix that step (1) is extracted carries out 8 * 8 piecemeal discrete cosine transforms, obtains the discrete cosine variation factor matrix of eigenmatrix;
3b) to the watermarking images matrix behind step (2) scramble by rows, obtain the one dimension watermark sequence;
3c) to one dimension watermark sequence piecemeal, obtain the watermark segmentation sequences.
(4) eigenmatrix of acquisition water mark inlaying:
4a) to discrete cosine variation factor matrix according to getting a piecemeal from left to right, from top to bottom, this piecemeal begins to obtain discrete cosine variation factor sequence according to the ordering of " it " font from last element;
4b) to the watermark segmentation sequences according to getting a piecemeal from front to back, piecemeal is got all elements successively, if the value of the element of getting is 1, then the element value with the discrete cosine transform coefficient sequence is revised as 20, otherwise be revised as-20, obtain the discrete cosine transform coefficient sequence of embed watermark;
4c) judge whether to have got all piecemeals of dct coefficient matrix, if do not got, execution in step 4a then), until all piecemeals of having got dct coefficient matrix, obtain the dct coefficient matrix of water mark inlaying;
4d) dct coefficient matrix to water mark inlaying carries out 8 * 8 piecemeal inverse discrete cosine transforms, obtains the eigenmatrix of water mark inlaying.
(5) obtain the piecemeal halftone image:
5a) to the carrier image of step (1), adopt image half accent method, partly mediate reason, obtain halftone image;
5b) halftone image is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain the piecemeal halftone image.
(6) embed watermark:
6a) the piecemeal halftone image is got a piecemeal from left to right, from top to bottom, calculate the piecemeal average, obtain the piecemeal average;
6b) eigenmatrix of water mark inlaying is got element element as a comparison from left to right, from top to bottom, the size of the value of this comparison element and piecemeal average relatively, if this comparison element value greater than the piecemeal average, then is revised as 255 to the value of a black picture element in the piecemeal; Otherwise, a white pixel value in the piecemeal is revised as 0, recomputates the piecemeal average, up to the absolute value of the difference of the value of this comparison element and piecemeal average less than 2 o'clock, no longer remove to revise the pixel value in the piecemeal, obtain a piecemeal in the water mark inlaying piecemeal halftone image;
6c) judge whether to have got all piecemeals of piecemeal halftone image, if do not got, execution in step 6a then), until all piecemeals of having got the piecemeal halftone image, obtain water mark inlaying piecemeal halftone image.
(7) search obtains optimum water mark inlaying halftone image:
According to from left to right, order is from top to bottom carried out the direct two-value search DBS method that only exchange is not overturn to each piecemeal, until obtaining optimum water mark inlaying halftone image, finishes watermark embed process to water mark inlaying piecemeal halftone image; Optimum water mark inlaying halftone image is printed, scanned, obtain scanning the image of back embed watermark.
The concrete steps of described watermark extraction process are as follows:
(8) image is corrected:
Image after utilizing Photoshop software to scanning carries out cutting and scaling, obtains containing the image of watermark.
(9) obtain to contain the watermark dct coefficient matrix:
9a) image that contains watermark is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain piecemeal and contain watermarking images;
9b) ask each piecemeal to contain the mean value of all pixels in the watermarking images, then according to from left to right, from top to bottom order forms
Size contain the watermarking images eigenmatrix, wherein P, Q represent width and the height value of carrier image respectively;
9c) carry out 8 * 8 piecemeal discrete cosine transforms to containing the watermarking images eigenmatrix, obtain containing the watermark dct coefficient matrix.
(10) extract watermark:
10a) to contain the watermark dct coefficient matrix from left to right, from top to bottom order gets 8 * 8 piecemeals, this piecemeal is begun to obtain containing watermark discrete cosine transform coefficient sequence according to the ordering of " it " font from last element;
10b) get successively contain watermark discrete cosine transform coefficient sequence before
Each element of individual element is judged, if element value is greater than 0, then watermark bit is set to 1, otherwise watermark bit is set to 0, obtain a piecemeal of watermark sequence, wherein U, V represent width and the height value of watermarking images respectively, and N represents the piecemeal number of piecemeal dct coefficient matrix;
10c) judge whether to have got all piecemeals that contain the watermark dct coefficient matrix, if do not got, execution in step 10a then), until having got all piecemeals that contain the watermark dct coefficient matrix, obtain watermark sequence;
10d) watermark sequence that obtains is transformed into the two-dimensional matrix of U * V according to vertical order, obtains the original watermark image, wherein U, V represent width and the height value of watermarking images respectively;
10e) the original watermark image is carried out contrary Arnold scramble, obtain the watermarking images that extracts.
Compared with prior art, the present invention has the following advantages:
First, the present invention is chosen in the frequency domain embed watermark, and is tie with the characteristic image, instructs generation spatial domain water mark inlaying partly to change the line map, overcome indifferent this shortcoming of the anti-printing-scanning attack of spatial domain method in the prior art, made the present invention have strong robustness and the good advantage of water mark inlaying picture quality.
Second, the present invention need not carry out binary conversion treatment to partly changing the line map of scanning before extracting watermark, the pixel value that has overcome prior art is being printed-scanning front and back instability, and work as printer, scanner models not simultaneously, threshold value is selected the shortcoming of difficulty, makes the present invention have the advantage of easier extraction watermarking images.
The 3rd, the watermark embedding method of the present invention structure has not only improved watermark capacity, and has overcome the shortcoming that watermark extracting in the existing similar technology needs original continuous figure, make the present invention have the watermark capacity height, can blind extraction advantage.
Description of drawings:
Fig. 1 is process flow diagram of the present invention;
Fig. 2 is the synoptic diagram of emulation 1 of the present invention;
Fig. 3 is the synoptic diagram of emulation 2 of the present invention;
Fig. 4 is the synoptic diagram of emulation 3 of the present invention;
Fig. 5 is the synoptic diagram of emulation 4 of the present invention.
Embodiment:
Below in conjunction with accompanying drawing the present invention is done detailed description.
Concrete steps with reference to accompanying drawing 1 the inventive method are as follows.
Step 1 is extracted characteristic image.
Carrier image is got 8 pixels from left to right, from top to bottom respectively carry out piecemeal, obtain block image.Calculate the mean value of the pixel value of all pixels that the piecemeal of block image comprises, then with mean value according to from left to right, from top to bottom order forms
The eigenmatrix of size, wherein P, Q represent width and the height value of carrier image respectively, the carrier image size of using in the embodiment of the invention is 2048 * 2048, so the eigenmatrix size that obtains is 256 * 256.
Step 2, the watermarking images pre-service.
Binary bitmap is carried out the Arnold scramble handle, obtain the watermarking images behind the scramble, scramble can strengthen the robustness of watermark opposing various attack.At first determine the Arnold scramble cycle of watermarking images, the scramble parameter can be selected greater than zero and less than the arbitrary integer in scramble cycle, the watermarking images size of using in the embodiment of the invention is 64 * 64, and its Arnold scramble cycle is 48, and selecting the scramble parameter is 20.
Step 3, watermark embeds preprocessing process.
The eigenmatrix that extracts is carried out 8 * 8 piecemeal discrete cosine transforms, obtain the dct coefficient matrix of eigenmatrix, by discrete cosine transform eigenmatrix is changed to frequency domain, can increase the robustness of watermark at the frequency domain water mark inlaying.
To the watermarking images matrix behind the scramble by rows, obtain the one dimension watermark sequence.The one dimension watermark sequence according to vertical order, is got at every turn
Get element as a piecemeal, up to all elements of having got the one dimension watermark sequence, wherein U, V represent width and the height value of watermarking images respectively, N represents the piecemeal number of piecemeal dct coefficient matrix, obtain the watermark segmentation sequences, the watermarking images size of using in the embodiment of the invention is 64 * 64, so U=64, V=64.
Step 4, the eigenmatrix of acquisition water mark inlaying.
The first step, to discrete cosine variation factor matrix according to getting a piecemeal from left to right, from top to bottom, this piecemeal begins to sort according to " it " font from last element, obtain discrete cosine variation factor sequence, the coefficient of the discrete cosine sequence that this method obtains is arranged according to the order from the high frequency to the low frequency, is conducive to the embedding of watermark in the following step.
Second step, to the watermark segmentation sequences according to getting a piecemeal from front to back, piecemeal is got all elements successively, if the value of the element of getting is 1, then the element value with discrete cosine variation factor sequence is revised as 20, otherwise be revised as-20, obtain the discrete cosine variation factor sequence of embed watermark, draw by lot of experiment results, the embedment strength value of watermark is 20 o'clock, the extraction effect of watermark is relatively good on the one hand, and the visual effect of image is relatively good after the embed watermark on the other hand, and these two aspects have obtained a well compromise.
The 3rd goes on foot, and judges whether to have got all piecemeals of discrete cosine variation factor matrix, if do not got, then forwards step 4 to and continues to carry out, and finally obtains the discrete cosine variation factor matrix of water mark inlaying.
The 4th step, the dct coefficient matrix of water mark inlaying is carried out 8 * 8 piecemeal inverse discrete cosine transforms, obtain the eigenmatrix of water mark inlaying.
Step 5 obtains the piecemeal halftone image.
Carrier image is partly mediated reason, obtain halftone image, half accent method of image has three classes, the one, dithering, the 2nd, error-diffusion method, the 3rd, direct two-value search procedure, the processing speed of dither method is fast, but visual effect is relatively poor, directly two-value searching method visual effect is best, but time complexity is the highest, and the visual effect of error-diffusion method and time complexity are between preceding two kinds of methods, so the present invention adopts the Floyd half accent method of the classics in the error-diffusion method that image is partly mediated reason.Halftone image is got 8 pixels from left to right, from top to bottom respectively carry out piecemeal, obtain the piecemeal halftone image.
Step 6, embed watermark.
The first step is got a piecemeal from left to right, from top to bottom to the piecemeal halftone image, calculates the piecemeal average, obtains the piecemeal average, and the piecemeal average here refers to the mean value of the pixel value of all pixels that this piecemeal comprises.
Second step, eigenmatrix to water mark inlaying is got an element from left to right, from top to bottom, element as a comparison, the size of the value of this comparison element and piecemeal average relatively, if this comparison element value is greater than the piecemeal average, then the value of a black picture element in the piecemeal is revised as 255, otherwise, the value of a white pixel in the piecemeal is revised as 0, recomputate the piecemeal average, less than 2, no longer remove to revise the pixel value in the piecemeal up to the absolute value of the difference of the value of this element and piecemeal average, obtain a piecemeal in the water mark inlaying piecemeal halftone image.It is 0 pixel that the black picture element here refers to pixel value, and it is 255 pixel that the white pixel here refers to pixel value.
The 3rd goes on foot, and judges whether to have got all piecemeals of piecemeal half tone image, if do not got, then carries out the first step, until obtaining water mark inlaying piecemeal halftone image.
Step 7, search obtains optimum water mark inlaying halftone image.
According to from left to right, order is from top to bottom carried out the direct two-value search DBS method that only exchange is not overturn to each piecemeal, until obtaining optimum water mark inlaying halftone image, finishes watermark embed process to water mark inlaying piecemeal halftone image; To optimum water mark inlaying halftone image print, scanning, the image after obtaining scanning, only the exchange direct two-value search DBS method of not overturning only refers to central element and the element of 8 neighborhoods exchanges, self does not overturn.
Step 8, image is corrected.
Utilize the automatic clipping function of Photoshop software that the image after scanning is carried out cutting, cut off the white edge that scans above the image that obtains, and by the scaling function of this software image zooming is arrived initial carrier image size, obtain containing the image of watermark.
Step 9 obtains to contain watermark discrete cosine variation factor matrix.
The image that contains watermark is got 8 pixels from left to right, from top to bottom respectively carry out piecemeal, obtain piecemeal and contain watermarking images.Ask the mean value of all pixels in each block image, then according to from left to right, from top to bottom order forms
Size contain the watermark eigenmatrix, wherein P, Q represent width and the height value of carrier image respectively, the carrier image size of using in the embodiment of the invention is 2048 * 2048, so P=2048, Q=2048.Carry out the variation of 8 * 8 piecemeal discrete cosines to containing the watermark eigenmatrix, obtain containing watermark discrete cosine variation factor matrix.
Step 10 is extracted watermark.
The first step, to contain watermark discrete cosine variation factor matrix from left to right, from top to bottom order gets 8 * 8 piecemeals, this piecemeal is begun to obtain containing watermark discrete cosine variation factor sequence according to the ordering of " it " font from last element.
Second the step, get successively contain watermark discrete cosine variation factor sequence before
Each element of individual element is judged, if element value is greater than 0, then watermark bit is set to 1, otherwise watermark bit is set to 0, obtain a piecemeal of watermark sequence, wherein U, V represent width and the height value of watermarking images respectively, and N represents piecemeal discrete cosine variation factor partitioning of matrix number.
The 3rd step judged whether to have got all piecemeals that contain watermark discrete cosine variation factor matrix, if do not got, then carried out the first step, until obtaining watermark sequence.
The 4th step, the watermark sequence that obtains is transformed into the two-dimensional matrix of U * V according to vertical order, obtains the original watermark image, wherein U, V represent width and the height value of watermarking images respectively, the watermarking images size of using in the embodiment of the invention is 64 * 64, so U=64, V=64.
In the 5th step, carry out the watermarking images that contrary Arnold scramble obtains extracting.The watermarking images size of using in the embodiment of the invention is 64 * 64, and its Arnold scramble cycle is 48, and selecting the scramble parameter in the embodiment of the invention is 20, so contrary Arnold scramble parameter is 28.
Below in conjunction with analogous diagram effect of the present invention is further described.
The printer model of selecting in the emulation of the present invention is HP Color LaserJet CP2025, and scanner models is EPSON Perfection1200U, and the resolution of printing and scanning all is 300dpi.Estimate the quality that contains watermarking images with Y-PSNR HPSNR, estimate the quality of extracting watermarking images with CDR (correct extraction ratio).Use the inventive method as follows to watermark embedding, extraction and the attack emulation of gray level image:
With reference to accompanying drawing 2, use model to be EPSON Perfection1200U scanner as HP Color LaserJet CP2025 printer and model in the emulation 1 of the present invention.Fig. 2 (a) is the image-carrier image, and size is that 2048 * 2048, Fig. 2 (b) is watermarking images, and size is 64 * 64.Use the inventive method, what obtain contains watermarking images such as Fig. 2 (c), HPSNR=33.4602, and, through image such as the Fig. 2 (d) after the print scanned rectification, the watermarking images of extraction such as Fig. 2 (e), CDR=93.72%;
The interpretation of result of emulation 1, from Fig. 2 (c) as can be seen, behind the embed watermark, the quality of image does not almost descend in the carrier image.From Fig. 2 (e) as can be seen, contain watermarking images and still can extract watermark clearly through printing, scanning, illustrate that the inventive method has very strong robustness to attacks of print_scan.
Emulation 2, with reference to using model to be EPSON Perfection1200U scanner as HP Color LaserJet CP2025 printer and model in accompanying drawing 3 emulation, Fig. 3 (a) is carrier image, and size is 2048 * 2048, Fig. 3 (b) is watermarking images, and size is 64 * 64.Fig. 3 (c) is for containing watermarking images.Carry out cutting and attack containing watermarking images, the cutting size is 1024 * 1024 white blocks, shown in Fig. 3 (d), the watermarking images of extraction shown in Fig. 3 (e), CDR=92.7%.By the result of emulation 2 as seen, the inventive method is attacked cutting and is had very strong robustness.
Emulation 3 with reference to accompanying drawing 4, uses model to be EPSON Perfection1200U scanner as HP Color LaserJet CP2025 printer and model in the emulation, Fig. 4 (a) is carrier image, size is that 2048 * 2048, Fig. 4 (b) is watermarking images, and size is 64 * 64.Fig. 4 (c) is for containing watermarking images.Add the salt-pepper noise attack to containing watermarking images, the plus noise parameter is 0.05, shown in Fig. 4 (d), the watermarking images that extracts, shown in Fig. 4 (e), CDR=100%, by the result of emulation 3 as seen, method of the present invention is attacked salt-pepper noise and is also had very strong robustness.
Emulation 4 is with reference to accompanying drawing 5.Use model to be EPSON Perfection1200U scanner as HP Color LaserJet CP2025 printer and model in the emulation, Fig. 5 (a) is carrier image, and size is that 2048 * 2048, Fig. 5 (b) is watermarking images, and size is 64 * 64.Fig. 5 (c) is for containing watermarking images.Alter attack at random to containing watermarking images, shown in Fig. 5 (d), the watermarking images of extraction shown in Fig. 5 (e), CDR=99.07%.By the result of emulation 4 as seen, the inventive method has very strong robustness equally to altering at random to attack.
Result by emulation can draw, use the inventive method obtain containing watermarking images through print scanned, alter, add salt-pepper noise and cutting and attack after, can extract watermark clearly.Illustrate that thus method of the present invention can resist print scanned, correction, cutting, add attacks such as salt-pepper noise, watermark has very strong robustness.
Claims (5)
1. the half water transfer impression method that combines of a frequency domain and spatial domain comprises two processes of watermark embedding and watermark extracting;
The concrete steps of described watermark embed process are:
(1) extract characteristic image:
1a) carrier image is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain block image;
1b) to each piecemeal average according to from left to right, from top to bottom order forms
The eigenmatrix of size, wherein P, Q represent width and the height value of carrier image respectively;
(2) watermarking images pre-service:
The binary bitmap matrix is carried out the Arnold scramble, obtain the watermarking images matrix behind the scramble;
(3) watermark embeds preprocessing process:
3a) eigenmatrix that step (1) is extracted carries out 8 * 8 piecemeal discrete cosine transforms, obtains the discrete cosine variation factor matrix of eigenmatrix;
3b) to the watermarking images matrix behind step (2) scramble by rows, obtain the one dimension watermark sequence;
3c) to one dimension watermark sequence piecemeal, obtain the watermark segmentation sequences;
(4) eigenmatrix of acquisition water mark inlaying:
4a) to discrete cosine variation factor matrix according to getting a piecemeal from left to right, from top to bottom, this piecemeal begins to obtain discrete cosine variation factor sequence according to the ordering of " it " font from last element;
4b) to the watermark segmentation sequences according to getting a piecemeal from front to back, piecemeal is got all elements successively, if the value of the element of getting is 1, then the element value with the discrete cosine transform coefficient sequence is revised as 20, otherwise be revised as-20, obtain the discrete cosine transform coefficient sequence of embed watermark;
4c) judge whether to have got all piecemeals of dct coefficient matrix, if do not got, execution in step 4a then), until all piecemeals of having got dct coefficient matrix, obtain the dct coefficient matrix of water mark inlaying;
4d) dct coefficient matrix to water mark inlaying carries out 8 * 8 piecemeal inverse discrete cosine transforms, obtains the eigenmatrix of water mark inlaying;
(5) obtain the piecemeal halftone image:
5a) to the carrier image of step (1), adopt image half accent method, partly mediate reason, obtain halftone image;
5b) halftone image is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain the piecemeal halftone image;
(6) embed watermark:
6a) the piecemeal halftone image is got a piecemeal from left to right, from top to bottom, calculate the piecemeal average, obtain the piecemeal average;
6b) eigenmatrix of water mark inlaying is got element element as a comparison from left to right, from top to bottom, the size of the value of this comparison element and piecemeal average relatively, if this comparison element value greater than the piecemeal average, then is revised as 255 to the value of a black picture element in the piecemeal; Otherwise, a white pixel value in the piecemeal is revised as 0, recomputates the piecemeal average, up to the absolute value of the difference of the value of this comparison element and piecemeal average less than 2 o'clock, no longer remove to revise the pixel value in the piecemeal, obtain a piecemeal in the water mark inlaying piecemeal halftone image;
6c) judge whether to have got all piecemeals of piecemeal halftone image, if do not got, execution in step 6a then), until all piecemeals of having got the piecemeal halftone image, obtain water mark inlaying piecemeal halftone image;
(7) search obtains optimum water mark inlaying halftone image:
According to from left to right, order is from top to bottom carried out the direct two-value search DBS method that only exchange is not overturn to each piecemeal, until obtaining optimum water mark inlaying halftone image, finishes watermark embed process to water mark inlaying piecemeal halftone image; Optimum water mark inlaying halftone image is printed, scanned, obtain scanning the image of back embed watermark;
The concrete steps of described watermark extraction process are as follows:
(8) image is corrected:
Image after utilizing Photoshop software to scanning carries out cutting and scaling, obtains containing the image of watermark;
(9) obtain to contain the watermark dct coefficient matrix:
9a) image that contains watermark is got 8 pixels from left to right, from top to bottom respectively and carry out piecemeal, obtain piecemeal and contain watermarking images;
9b) ask each piecemeal to contain the mean value of all pixels in the watermarking images, then according to from left to right, from top to bottom order forms
Size contain the watermarking images eigenmatrix, wherein P, Q represent width and the height value of carrier image respectively;
9c) carry out 8 * 8 piecemeal discrete cosine transforms to containing the watermarking images eigenmatrix, obtain containing the watermark dct coefficient matrix;
(10) extract watermark:
10a) to contain the watermark dct coefficient matrix from left to right, from top to bottom order gets 8 * 8 piecemeals, this piecemeal is begun to obtain containing watermark discrete cosine transform coefficient sequence according to the ordering of " it " font from last element;
10b) get successively contain watermark discrete cosine transform coefficient sequence before
Each element of individual element is judged, if element value is greater than 0, then watermark bit is set to 1, otherwise watermark bit is set to 0, obtain a piecemeal of watermark sequence, wherein U, V represent width and the height value of watermarking images respectively, and N represents the piecemeal number of piecemeal dct coefficient matrix;
10c) judge whether to have got all piecemeals that contain the watermark dct coefficient matrix, if do not got, execution in step 10a then), until having got all piecemeals that contain the watermark dct coefficient matrix, obtain watermark sequence;
10d) watermark sequence that obtains is transformed into the two-dimensional matrix of U * V according to vertical order, obtains the original watermark image, wherein U, V represent width and the height value of watermarking images respectively;
10e) the original watermark image is carried out contrary Arnold scramble, obtain the watermarking images that extracts.
2. the half water transfer impression method that combines of a kind of frequency domain according to claim 1 and spatial domain, it is characterized in that: the one dimension watermark sequence block division method step 3c) is to the vertical order of one dimension watermark sequence, to get at every turn
Get element as a piecemeal, up to all elements of having got the one dimension watermark sequence, wherein U, V represent width and the height value of watermarking images respectively, and N represents piecemeal discrete cosine variation factor partitioning of matrix number.
3. the half water transfer impression method that combines of a kind of frequency domain according to claim 1 and spatial domain, it is characterized in that: black picture element refers to step 6b), pixel value is 0 pixel.
4. the half water transfer impression method that combines of a kind of frequency domain according to claim 1 and spatial domain, it is characterized in that: white pixel refers to step 6b), pixel value is 255 pixel.
5. the half water transfer impression method that combines of a kind of frequency domain according to claim 1 and spatial domain, it is characterized in that: the method for the direct two-value search DBS that the only exchange described in the step (7) is not overturn refers to, central element only and the element of 8 neighborhoods exchange, self does not overturn.
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| CN107133906A (en) * | 2017-04-28 | 2017-09-05 | 安徽四创电子股份有限公司 | A kind of video source tracing method based on digital watermark |
| CN107730432A (en) * | 2017-08-31 | 2018-02-23 | 上海壹账通金融科技有限公司 | Image processing method and application server |
| CN108257073A (en) * | 2018-01-17 | 2018-07-06 | 北京新东方迅程网络科技股份有限公司 | A kind of invisible watermark embedding grammar and Blind extracting method |
| CN108961138A (en) * | 2017-05-19 | 2018-12-07 | 哈罗公司 | The insertion and extracting method of watermark data |
| CN109461110A (en) * | 2018-10-11 | 2019-03-12 | 阿里巴巴集团控股有限公司 | Determine the method and device of the information of tracing to the source of picture |
| CN111768328A (en) * | 2020-07-07 | 2020-10-13 | 中国科学院自动化研究所 | Text image watermark embedding method and system and text image watermark extracting method and system |
| CN111932432A (en) * | 2020-10-14 | 2020-11-13 | 腾讯科技（深圳）有限公司 | Blind watermark implanting method, blind watermark detecting method, blind watermark implanting device, blind watermark detecting equipment and storage medium |
| CN112017097A (en) * | 2020-08-27 | 2020-12-01 | 豪威科技(武汉)有限公司 | Watermark adding method, device, terminal and computer readable storage medium |
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| CN107133906A (en) * | 2017-04-28 | 2017-09-05 | 安徽四创电子股份有限公司 | A kind of video source tracing method based on digital watermark |
| CN108961138B (en) * | 2017-05-19 | 2023-05-26 | 快照标签株式会社 | Watermark data embedding and extracting method |
| CN108961138A (en) * | 2017-05-19 | 2018-12-07 | 哈罗公司 | The insertion and extracting method of watermark data |
| CN107730432A (en) * | 2017-08-31 | 2018-02-23 | 上海壹账通金融科技有限公司 | Image processing method and application server |
| CN108257073A (en) * | 2018-01-17 | 2018-07-06 | 北京新东方迅程网络科技股份有限公司 | A kind of invisible watermark embedding grammar and Blind extracting method |
| CN109461110A (en) * | 2018-10-11 | 2019-03-12 | 阿里巴巴集团控股有限公司 | Determine the method and device of the information of tracing to the source of picture |
| CN109461110B (en) * | 2018-10-11 | 2023-06-27 | 创新先进技术有限公司 | Method and device for determining traceability information of picture |
| CN109685708B (en) * | 2018-12-26 | 2024-02-06 | 珠海奔图电子有限公司 | Image processing method and device, electronic equipment and computer readable storage medium |
| CN111768328A (en) * | 2020-07-07 | 2020-10-13 | 中国科学院自动化研究所 | Text image watermark embedding method and system and text image watermark extracting method and system |
| CN111768328B (en) * | 2020-07-07 | 2021-08-13 | 中国科学院自动化研究所 | Text image watermark embedding method and system and text image watermark extracting method and system |
| CN112017097A (en) * | 2020-08-27 | 2020-12-01 | 豪威科技(武汉)有限公司 | Watermark adding method, device, terminal and computer readable storage medium |
| CN112017097B (en) * | 2020-08-27 | 2024-03-08 | 豪威科技(武汉)有限公司 | Watermark adding method, watermark adding device, terminal and computer readable storage medium |
| CN111932432A (en) * | 2020-10-14 | 2020-11-13 | 腾讯科技（深圳）有限公司 | Blind watermark implanting method, blind watermark detecting method, blind watermark implanting device, blind watermark detecting equipment and storage medium |
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