CN108551539A - A kind of encryption method of highly concealed type image false-proof information - Google Patents
A kind of encryption method of highly concealed type image false-proof information Download PDFInfo
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- CN108551539A CN108551539A CN201810345906.5A CN201810345906A CN108551539A CN 108551539 A CN108551539 A CN 108551539A CN 201810345906 A CN201810345906 A CN 201810345906A CN 108551539 A CN108551539 A CN 108551539A
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- image
- constituency
- counterfeiting information
- half tone
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
- H04N1/32101—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
- H04N1/32144—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
- H04N1/32149—Methods relating to embedding, encoding, decoding, detection or retrieval operations
- H04N1/32267—Methods relating to embedding, encoding, decoding, detection or retrieval operations combined with processing of the image
- H04N1/32272—Encryption or ciphering
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/32—Circuits or arrangements for control or supervision between transmitter and receiver or between image input and image output device, e.g. between a still-image camera and its memory or between a still-image camera and a printer device
- H04N1/32101—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title
- H04N1/32144—Display, printing, storage or transmission of additional information, e.g. ID code, date and time or title embedded in the image data, i.e. enclosed or integrated in the image, e.g. watermark, super-imposed logo or stamp
- H04N1/32149—Methods relating to embedding, encoding, decoding, detection or retrieval operations
- H04N1/32203—Spatial or amplitude domain methods
- H04N1/32256—Spatial or amplitude domain methods in halftone data
Abstract
The invention discloses a kind of encryption methods of highly concealed type image false-proof information, include the following steps：(1), prepare original copy and anti-counterfeiting information；(2), digital screening is handled；(3), anti-counterfeiting information is encrypted；(4), image synthesizes.The range of choice bigger of original copy and anti-counterfeiting information of the present invention realizes that encryption and decoding, concealment and extraction recognition performance are stronger in continuous toned image.
Description
Technical field
The invention belongs to grating field of anti-counterfeit technology, and in particular to a kind of encryption side of highly concealed type image false-proof information
Method.
Background technology
Current main printing anti-counterfeiting technology is printed based on the basis of high-precision equipment and special material mostly
Anti-counterfeiting cost is higher, and once prints anti-fake material and facility used and be obtained, and will be imitated by massive duplication, from
And anti-fake effect will be lost.Image, the word etc. for needing print reproduction are typically each exported by halftone screen, are based on
The grating anti-counterfeiting technology of moir patterns, aiming at the working condition of present printing anti-counterfeiting technology and common printed enterprise, proposition
A kind of small according to lazyness to equipment and material, anti-pseudoprocess is simple, the anti-fake new technology of the good halftoning of antifalse effect.Its basic principle
The principle features exactly formed to Moire fringe common in printing are analyzed and researched, special in conjunction with digital halftone screening technology
Point, the visual characteristic based on human eye, by during digital screening, under the premise of human eye vision will not be caused to change pair plus
The part site of net image carries out micro adjustment, to complete the addition of anti-counterfeiting information.
In the prior art, the type selecting of anti-counterfeiting information is confined to simple shape and single letter, with the increasing of anti-counterfeiting information
The concealment of big and complexity raising, anti-counterfeiting information declines, and is easily directly discovered by human eye, and concealment and extraction recognition performance are equal
It is not ideal enough.
Invention content
The object of the present invention is to provide a kind of encryption method of highly concealed type image false-proof information, original copy and anti-counterfeiting information
Range of choice bigger realizes that encryption and decoding, concealment and extraction recognition performance are stronger in continuous toned image.
The present invention provides the following technical solutions：A kind of encryption method of highly concealed type image false-proof information, including such as
Lower step：
Step 1: preparing original copy and anti-counterfeiting information
Continuous toned image is selected as original copy, selects word or figure as anti-counterfeiting information, continuous toned image and anti-fake
Information is digital file format；
Original copy is opened in image processing software, sets original copy to tetra- Color Channel patterns of C, M, Y, K, selection is wherein
1 Color Channel is as encrypted tunnel, remaining 3 channel is as Common passageway；
Step 2: digital screening is handled
Using am screening technology, screening parameter is set, half color of encrypted tunnel being made of site is obtained after screening processing
It changes the line map picture and the common half tone image of 3 width；
Newly-built blank image, image size is identical with the image size of common half tone image, and blank image is arranged
For tetra- Color Channel patterns of C, M, Y, K, the common half tone image of 3 width is copied into corresponding Color Channel, it is spare；
Step 3: anti-counterfeiting information is encrypted
(1), site is moved
Anti-counterfeiting information is superimposed upon in the figure layer of encrypted tunnel half tone image, acquires the profile of anti-counterfeiting information, encrypted
Encryption corresponding with profile constituency is obtained in the figure layer of channel half tone image, remembers the site in encrypted tunnel half tone image
Sum is m*n, remembers that the site in encrypted tunnel half tone image is (i, j), i=1,2 ... m, j=1,2 ... n, note plus
The collection of the close all sites in constituency is combined into G={ (i, j), i≤m；J≤n }, note encrypts the set of the site in boundary bottom in constituency
For J={ (i, j), (i, j) ∈ G }, in note encryption constituency at the top of boundary and the collection of the site of both sides be combined into E=(i, j),
(i, j) ∈ G }, the collection that note encrypts the site in boundary in constituency is combined into D={ (i, j), (i, j) ∈ G }, J+E+D=G；
The site of set E and set D is subjected to displacement, direction of displacement is that vertically upward, shift length is two neighboring net
The 1/2 of point distance；The site of set J is subjected to displacement, direction of displacement be vertically upward, shift length be two neighboring site away from
From 1/4；
(2), dot percentage adjusts
Remember that the dot percentage of each site in encrypted tunnel half tone image is f(i, j), all nets in encryption constituency
In point, the dot percentage for being located at the site of boundary bottom is fJ (i, j), boundary top and the dot percentage of the site of both sides are
fE (i, j), the dot percentage of the site in boundary is fD (i, j)；
After the movement of site, adjustment is located at the dot percentage of the site on boundary, any site (i, j) in set E, phase
Adjacent 8 sites are (i-1, j-1), (i-1, j), (i-1, j+1), (i, j-1), (i, j+1), (i+1, j-1), (i+1, j) and (i
+ 1, j+1), the percentage of adjacent 8 sites is f(i-1, j-1)、f(i-1, j)、f(i-1, j+1)、f(i, j-1)、f (i, j+1)、f(i+1, j-1)、
f(i+1, j)And f(i+1, j+1), the percentage of site (i, j) is adjusted to f 'E (i, j),
Any site (i, j) in set J, adjacent 8 sites be (i-1, j-1), (i-1, j), (i-1, j+1),
The percentage of (i, j-1), (i, j+1), (i+1, j-1), (i+1, j) and (i+1, j+1), adjacent 8 sites are f(i-1, j-1)、
f(i-1, j)、f(i-1, j+1)、f(i, j-1)、f(i, j+1)、f(i+1, j-1)、f(i+1, j)And f(i+1, j+1), the percentage of site (i, j) is adjusted
For f 'J (i, j)：
(3), after the completion of site movement and dot percentage adjust, the encrypted tunnel half-tone picture with anti-counterfeiting information is obtained
Picture；
Step 4: image synthesizes
The encrypted tunnel half tone image with anti-counterfeiting information that step 3 obtains is copied into step 2 blank image to remain
In remaining Color Channel, the original copy half tone image for being embedded with anti-counterfeiting information is obtained, completes encryption；
Step 5: decoding
Using the linear grating of digital file format as digital solution chip, linear grating is by color lump on the spot and transparent color lump
It is alternatively arranged composition, color lump and transparent color lump are the identical rectangular configuration of length on the spot, calculate color lump and transparent color lump on the spot
Width, obtain digital solution chip, by digital solution chip be covered in it is described be embedded on the original copy half tone image of anti-counterfeiting information,
Until observing anti-counterfeiting information, completion decodes for rotation and mobile digital solution chip.
As further describing for above-mentioned technical proposal：
In the step 2, screening parameter includes 4 screen angles, respectively 0 °, 15 °, 45 ° and 75 °, to encrypted tunnel
Digital screening processing is carried out respectively with 3 Common passageways, and the screen angle of encrypted tunnel is 0 °, the screening angle of 3 Common passageways
Degree is the arbitrary combination of 15 °, 45 ° and 75 ° threes
As further describing for above-mentioned technical proposal：
In the step 2, digital screening processing and newly-built blank image are all made of photoshop softwares,
Original copy is opened in photoshop, sets original copy to tetra- Color Channel patterns of C, M, Y, K, setting C-channel is logical as encryption
Color Channel is first converted to bitmap by road, M, Y, K channel as Common passageway, and output resolution ratio is arranged in when conversion, then uses
Half adjusts screen to carry out screening processing respectively to each Color Channel, and screening parameter further includes dot shape and screen frequency, site
Shape is round or rectangular, and screen frequency is 50~200lpi, the resolution ratio of the blank image and the output resolution ratio
It is identical.
As further describing for above-mentioned technical proposal：
In the step 2, digital screening processing and newly-built blank image are all made of photoshop softwares,
Original copy is opened in photoshop, sets original copy to tetra- Color Channel patterns of C, M, Y, K, setting C-channel is logical as encryption
Four Color Channels are first respectively converted into bitmap by road, M, Y, K channel as Common passageway, and output resolution ratio is arranged in when conversion
For 960dpi, then screen is adjusted to carry out screening processing respectively to each Color Channel using half, screening parameter further includes site shape
Shape and screen frequency, dot shape are circle, screen frequency 96lpi, the resolution ratio of the blank image and the output point
Resolution is identical.
As further describing for above-mentioned technical proposal：
In the step 5, document color lump width be T1, the width of transparent color lump is T2, note screen frequency is L, T1
+T2=25.4/L.
As further describing for above-mentioned technical proposal：
In the step 5, the computational methods of color lump width are on the spot：
The image region of a rectangle is selected on encrypted tunnel half tone image, image region is by encrypting constituency and comparison
Constituency forms, and encryption constituency is located at the middle of image region and accounts for the 50~80% of image region；
Measure the dot percentage f of each site in comparison constituency(i, j), the site with maximum value is obtained, on the spot color lump
Width T1Equal to the height of the site.
As further describing for above-mentioned technical proposal：
The step 4 further includes that will be embedded with the original copy half tone image the output for printing of anti-counterfeiting information, passes through computer control
System exposure output at printing plate, or it is corresponding film be made shine seal carving version again, the original copy for obtaining being embedded with anti-counterfeiting information is in kind；
The step 5 further includes that digital solution chip is prepared into corresponding grating in kind, and grating in kind is covered in original copy reality
On object, until observing anti-counterfeiting information, completion decodes for rotation and moving object grating.
As further describing for above-mentioned technical proposal：
In the step 3, the dot percentage for encrypting site in constituency is no more than 50%.
As further describing for above-mentioned technical proposal：
In the step 3, the preparation method for encrypting constituency is：Encrypted tunnel half-tone picture is opened in photoshop
Picture obtains the figure layer of encrypted tunnel half tone image, then creates figure layer and is placed into anti-counterfeiting information, obtains anti-counterfeiting information figure layer,
The profile of anti-counterfeiting information is chosen, anti-counterfeiting information figure layer is then deleted, obtains profile constituency, profile constituency is adjusted so that
Site in constituency is complete site, and the profile constituency obtained after adjustment is to encrypt constituency.
Beneficial effects of the present invention：The range of choice bigger of original copy and anti-counterfeiting information realizes encryption in continuous toned image
And decoding, concealment and extraction recognition performance are stronger, specific as follows：
(1), in ciphering process of the invention：Low-frequency filter characteristics based on human eye vision are carried out to continuous tone
After am screening processing, changes the dot location and dot percentage of regional area in encrypted tunnel, anti-counterfeiting information is embedded into
Among original image, reach the encrypted purpose of anti-counterfeiting information；In decoding process：Based on the anti-fake principle of moir patterns grating, using saturating
The grating of half tone image and design after screening to match is superimposed, presents a contrast strongly by the optical characteristics for penetrating grating
Longitudinal Moire fringe phenomenon of period infinity reach the decoded purpose of anti-counterfeiting information to show anti-counterfeiting information；
(2), the selection range of original copy of the present invention is wider：In the prior art, it is limited by encryption method, if using connecting
Continuous change the line map is encrypted, and concealment is poor, therefore usually uniform dot percentage, which is only arranged, obtains original image into row information
It is hidden, the present invention solves the problems, such as that in continuous toned image, encryption and decoding effect are poor, original copy selection range more
Greatly；
(3), the selection of anti-counterfeiting information of the present invention is more various and capacity bigger：Anti-counterfeiting information can select figure or text
Word, and the capacity bigger of its anti-counterfeiting information can still keep preferable structural similarity and decoding to imitate with the increase of capacity
Fruit；
(4), the encrypted concealment of the present invention is stronger：Site in boundary bottom in encryption constituency is moved 1/ vertically upward
4 site spacing (site spacing is determined by parameters such as screen frequencies), the other sites for encrypting constituency are moved vertically upward
1/2 site spacing, in this manner, more traditional displacement algorithm and other innovatory algorithms can realized not
On the basis of your line is anti-fake, encryption constituency is further decreased due to visual perception caused by the displacement of site；In addition, by changing net
Point percentage so that the site of borderline region can further be blended with the site of surrounding, using with neighbouring site and hundred
The vision shake for dividing the mode smeared out boundary site of ratio, compared to the prior art, can preferably improve the hidden of anti-counterfeiting information
Performance makes it be not easy to be visually perceived；In addition, the site to boundaries on either side is equally improved, constituency is encrypted in conjunction with the present invention
Preparation method, the site of boundaries on either side can keep integrality, while can also still have preferable hidden after site is improved
Performance is covered, after the superposition of especially four chrominance channels, human eye can not Direct Recognition anti-counterfeiting information；The encryption method of the present invention, it is comprehensive
It considers boundary node and shakes the visual perception that will produce, improve the compatibility of boundary node and surrounding site, encryption method is more
It is scientific and reasonable, while coordinating adaptable coding/decoding method, it can effectively realize the hiding and extraction of anti-counterfeiting information；
(5), the present invention has good decoding effect：By grating decoding piece, can be accurately identified under special angle
Anti-counterfeiting information reaches antifalse effect, not by the improved influence of Encryption Algorithm；
(6), the present invention can prefabricated decoding effect：The encryption anti-fake information in continuous toned image, and make corresponding number
Word decoding piece can be decoded, prefabricated detection result before image printing output with digital solution chip detection anti-counterfeiting information,
It is convenient that encrypted image is verified, there is early warning effect, then use corresponding data creating material object lenticular lenses；
(7), the preparation method in present invention encryption constituency is more simple accurate, is directly made on encrypted tunnel half tone image
Make profile constituency, and be adjusted so that the site in constituency is complete site, compared to the prior art in, in screening
The method in prefabricated constituency in preceding encrypted tunnel, method of the invention can accurately select complete site；
(8), the product that the present invention obtains is difficult to copy：The site of the present invention improves and is difficult to be cracked, in ciphering process
The parameters of setting also can not be penetrated accurately by counterfeiter, slightly different, vision will be caused to change in decoding process, prevent
Pseudo- performance is stronger.
Description of the drawings
Attached drawing is used to provide further understanding of the present invention, and a part for constitution instruction, the reality with the present invention
It applies example to be used to explain the present invention together, not be construed as limiting the invention.In the accompanying drawings：
Fig. 1 is the original copy in the embodiment of the present invention (color information is not shown)；
Fig. 2 is the encrypted tunnel half tone image in the embodiment of the present invention；
Fig. 3 is the channels the M Screening Image in the embodiment of the present invention；
Fig. 4 is the channels the Y Screening Image in the embodiment of the present invention；
Fig. 5 is the K channel Screening Image in the embodiment of the present invention；
Fig. 6 is the original copy half tone image for being embedded with anti-counterfeiting information in the embodiment of the present invention (color information is not shown)；
Fig. 7 is the decoded original copy half tone image in the embodiment of the present invention (color information is not shown)；
Fig. 8 is the close-up schematic view of the channels Y Screening Image in Fig. 4.
Specific implementation mode
Present invention will be further explained below with reference to specific examples.These embodiments are merely to illustrate the present invention and do not have to
In limiting the scope of the invention.In conjunction with Figure of description, the design feature that the present invention will be described in detail.
A kind of encryption method of highly concealed type image false-proof information, includes the following steps：
Step 1: preparing original copy and anti-counterfeiting information
Referring to Fig. 1, select continuous toned image as original copy, select Chinese character " day " as anti-counterfeiting information, continuous toned image and
Anti-counterfeiting information is digital file format；
Original copy is opened in photoshop, is set original copy to tetra- Color Channel patterns of C, M, Y, K, is selected the channels C
As encrypted tunnel, M, Y, K channel are as Common passageway, and the region for selecting encrypted tunnel scala media leveling slow is as anti-counterfeiting information
Encryption section；
Step 2: digital screening is handled
In photoshop, four Color Channels are first respectively converted into bitmap, setting output resolution ratio is when conversion
Then 960 dpi adjust screen to carry out screening processing respectively to each Color Channel using half；
Using am screening technology, the screening parameter of each Color Channel is set, screening parameter includes dot shape, screening
Line number and screen angle, dot shape are circle, and screen frequency is 96lpi, screen angle be respectively 0 °, 15 °, 45 ° and
75 °, wherein the screen angle of C-channel be 0 °, M, Y, K channel screen angle correspond to 15 °, 45 ° and 75 °；
The encrypted tunnel half tone image being made of site as shown in Fig. 2,3,4 and 5 is obtained after screening processing and 3 general
Logical half tone image, the common half tone image of 3 width is respectively the channels M Screening Image, the channels Y Screening Image and the channels K screening figure
Picture；
In photoshop, blank image, resolution ratio 960dpi, image size and common half-tone picture are created
The image size of picture is identical, and the image size of common half tone image can be directly read in photoshop, and blank image is set
Tetra- Color Channel patterns of C, M, Y, K are set to, the common half tone image of 3 width is copied into corresponding Color Channel, it is spare；
Step 3: anti-counterfeiting information is encrypted
(1), site is moved
Anti-counterfeiting information is superimposed upon in the figure layer of encrypted tunnel half tone image, acquires the profile of anti-counterfeiting information, encrypted
Encryption corresponding with profile constituency is obtained in the figure layer of channel half tone image, remembers the site in encrypted tunnel half tone image
Sum is m*n, remembers that the site in encrypted tunnel half tone image is (i, j), i=1,2 ... m, j=1,2 ... n, note plus
The collection of the close all sites in constituency is combined into G={ (i, j), i≤m；J≤n }, note encrypts the set of the site in boundary bottom in constituency
For J={ (i, j), (i, j) ∈ G }, in note encryption constituency at the top of boundary and the collection of the site of both sides be combined into E=(i, j),
(i, j) ∈ G }, the collection that note encrypts the site in boundary in constituency is combined into D={ (i, j), (i, j) ∈ G }, J+E+D=G；
The dot percentage for encrypting site in constituency is that the site of set E and set D is carried out displacement no more than 50%,
Direction of displacement is that vertically upward, shift length is the 1/2 of two neighboring site distance；The site of set J is subjected to displacement, displacement
Direction is that vertically upward, shift length is the 1/4 of two neighboring site distance；The displacement operation of site directly exists in the present embodiment
It is carried out using mobile tool after choosing site in photoshop；
(2), dot percentage adjusts
Remember that the dot percentage of each site in encrypted tunnel half tone image is f(i, j), all nets in encryption constituency
In point, the dot percentage for being located at the site of boundary bottom is fJ (i, j), boundary top and the dot percentage of the site of both sides are
fE (i, j), the dot percentage of the site in boundary is fD (i, j)；
After the movement of site, adjustment is located at the dot percentage of the site on boundary, any site (i, j) in set E, phase
Adjacent 8 sites are (i-1, j-1), (i-1, j), (i-1, j+1), (i, j-1), (i, j+1), (i+1, j-1), (i+1, j) and (i
+ 1, j+1), the percentage of adjacent 8 sites is f(i-1, j-1)、f(i-1, j)、f(i-1, j+1)、f(i, j-1)、f (i, j+1)、f(i+1, j-1)、
f(i+1, j)And f(i+1, j+1), the percentage of site (i, j) is adjusted to f 'E (i, j),
Any site (i, j) in set J, adjacent 8 sites be (i-1, j-1), (i-1, j), (i-1, j+1),
The percentage of (i, j-1), (i, j+1), (i+1, j-1), (i+1, j) and (i+1, j+1), adjacent 8 sites are f(i-1, j-1)、
f(i-1, j)、f(i-1, j+1)、f(i, j-1)、f(i, j+1)、f(i+1, j-1)、f(i+1, j)And f(i+1, j+1), the percentage of site (i, j) is adjusted
For f 'J (i, j)：
The change operation of dot percentage carries out directly in photoshop in the present embodiment, it would be desirable to the site of change
Then removal has the site of corresponding percentage in original position merging；
(3), referring to Fig. 6 the encrypted tunnel with anti-counterfeiting information is obtained after the completion of site movement and dot percentage adjustment
Half tone image, it can be seen that the present embodiment improves the site for encrypting constituency, due to human eye low-frequency filter characteristics,
Hiding information " day " can not be almost observed in figure 6.
Step 4: image synthesizes
Referring to Fig. 7, the encrypted tunnel half tone image with anti-counterfeiting information that step 3 obtains is copied into step 2 sky
In the remaining Color Channel of white image, in Fig. 7 after four Color Channels merging, " day " can not with the naked eye observe, preferably
Realize Information hiding, obtain the original copy half tone image for being embedded with anti-counterfeiting information, complete encryption；
Step 5: decoding
Using the linear grating of digital file format as digital solution chip, linear grating is by color lump on the spot and transparent color lump
It is alternatively arranged composition, color lump and transparent color lump are the identical rectangular configuration of length on the spot, calculate color lump and transparent color lump on the spot
Width, obtain digital solution chip, by digital solution chip be covered in it is described be embedded on the original copy half tone image of anti-counterfeiting information,
Until observing anti-counterfeiting information " day ", completion decodes for rotation and mobile digital solution chip.
Furtherly, in the step 6, document color lump width be T1, the width of transparent color lump is T2, remember screening line
Number is L, T1、T2Meet with the relationship of L：T1+T2=25.4/L, on the spot color lump width T1Computational methods be specially：
(1), on encrypted tunnel half tone image select a rectangle image region, image region by encrypt constituency and
Constituency composition is compared, encryption constituency is located at the middle of image region and accounts for the 50~80% of image region；
(2), the dot percentage f of each site in comparison constituency is measured(i, j), the site with maximum value is obtained, on the spot
The width T of color lump1Equal to the height of the site, which, using amplifier, figure layer can be amplified in photoshop
It is calculated after maximum ratio, determines T1Width after, you can to use foregoing relationships to obtain T2Width.
In the present embodiment, the preparation method for encrypting constituency is：Encrypted tunnel half tone image is opened in photoshop,
The figure layer of encrypted tunnel half tone image is obtained, figure layer is then created and is placed into anti-counterfeiting information, obtain anti-counterfeiting information figure layer, choose
Then the profile of anti-counterfeiting information deletes anti-counterfeiting information figure layer, obtains profile constituency, profile constituency is adjusted so that constituency
Interior site is complete site, and the profile constituency obtained after adjustment is to encrypt constituency.
In the present embodiment, the distance between two neighboring site is fixed value d, d=25.4/L.
In the present embodiment, step 4 further includes that will be embedded with the original copy half tone image the output for printing of anti-counterfeiting information, is passed through
Computer control exposure output is made film and shines seal carving version again at printing plate, or correspondence, obtains the original for being embedded with anti-counterfeiting information
Original text is in kind；Step 5 further includes that digital solution chip is prepared into corresponding grating in kind, and grating in kind is covered on original copy material object,
Until observing anti-counterfeiting information, completion decodes for rotation and moving object grating.
Comparative example
On the basis of embodiment, the difference is that step 3, information is encrypted to be carried out comparative example using conventional method,
The original copy half tone image for being embedded with anti-counterfeiting information is obtained, specifically, the site in encryption constituency only carries out displacement, does not improve site
Percentage, and the direction of displacement is longitudinal or lateral, remembers that the distance between neighbour node is d, displacement is 1/2d, is added
Close channel half tone image and the common half tone image of 3 width.
By in embodiment 1 encrypted tunnel half tone image and the common half tone image of 3 width merge, obtain being not embedded into anti-fake
The original copy half tone image of information evaluates embodiment respectively using SSIM (structural similarity) algorithms and WSNR (weighted signal-to-noise ratio)
It is not embedded into the original copy half tone image of anti-counterfeiting information in 1 and is embedded with the phase of the original copy half tone image of anti-counterfeiting information between the two
Like degree；
By in comparative example encrypted tunnel half tone image and the common half tone image of 3 width merge, obtain being not embedded into anti-fake
The original copy half tone image of information evaluates comparative example respectively using SSIM (structural similarity) algorithms and WSNR (weighted signal-to-noise ratio)
In be not embedded into anti-counterfeiting information original copy half tone image and be embedded with the phase of the original copy half tone image of anti-counterfeiting information between the two
Like degree, to obtain the concealed evaluation result of anti-counterfeiting information indirectly, as shown in table 1 below：
1 similarity evaluation result of table
Wherein, the value of SSIM is bigger closer to the value of 1 or WSNR, and the similarity for representing two images is bigger, by upper
Table 1 is stated it is found that the SSIM values of embodiment are closer to 1, and WSNR is larger, therefore the method for the present invention, concealment effect is more preferable,
It is not easy to be detected by human eye.
The foregoing is only a preferred embodiment of the present invention, is not intended to restrict the invention, although with reference to aforementioned reality
Applying example, invention is explained in detail, for those skilled in the art, still can be to aforementioned each implementation
Technical solution recorded in example is modified or equivalent replacement of some of the technical features.All essences in the present invention
With within principle, any modification, equivalent replacement, improvement and so on should all be included in the protection scope of the present invention god.
Claims (10)
1. a kind of encryption method of highly concealed type image false-proof information, which is characterized in that include the following steps：
Step 1: preparing original copy and anti-counterfeiting information
It selects continuous toned image as original copy, selects word or figure as anti-counterfeiting information, continuous toned image and anti-counterfeiting information
It is digital file format；
Original copy is opened in image processing software, is set original copy to tetra- Color Channel patterns of C, M, Y, K, is selected wherein 1
Color Channel is as encrypted tunnel, remaining 3 channel is as Common passageway；
Step 2: digital screening is handled
Using am screening technology, screening parameter is set, the encrypted tunnel half-tone picture being made of site is obtained after screening processing
Picture and the common half tone image of 3 width；
Newly-built blank image, image size is identical with the image size of common half tone image, by blank image be set as C,
The common half tone image of 3 width is copied into corresponding Color Channel by M, tetra- Color Channel patterns of Y, K, spare；
Step 3: anti-counterfeiting information is encrypted
(1), site is moved
Anti-counterfeiting information is superimposed upon in the figure layer of encrypted tunnel half tone image, the profile of anti-counterfeiting information is acquired, in encrypted tunnel
Encryption corresponding with profile constituency is obtained in the figure layer of half tone image, remembers the total dot in encrypted tunnel half tone image
Be m*n, remember that the site in encrypted tunnel half tone image is (i, j), i=1,2 ... m, j=1,2 ... n, note encryption choosing
The collection of all sites in area is combined into G={ (i, j), i≤m；J≤n }, the collection that note encrypts in constituency in the site of boundary bottom is combined into J
={ (i, j), (i, j) ∈ G }, note encryption are combined into E={ (i, j), (i, j) at the top of boundary in constituency with the collection of the site of both sides
∈ G }, the collection that note encrypts the site in boundary in constituency is combined into D={ (i, j), (i, j) ∈ G }, J+E+D=G；
The site of set E and set D are subjected to displacement, direction of displacement be vertically upward, shift length for two neighboring site away from
From 1/2；The site of set J is subjected to displacement, direction of displacement is that vertically upward, shift length is two neighboring site distance
1/4；
(2), dot percentage adjusts
Remember that the dot percentage of each site in encrypted tunnel half tone image is f(i, j), all sites in encryption constituency
In, the dot percentage for being located at the site of boundary bottom is fJ (i, j), boundary top and the dot percentage of the site of both sides are
fE (i, j), the dot percentage of the site in boundary is fD (i, j)；
After the movement of site, adjustment is positioned at the dot percentage of the site on boundary, any site (i, j) in set E, and adjacent 8
A site is (i-1, j-1), (i-1, j), (i-1, j+1), (i, j-1), (i, j+1), (i+1, j-1), (i+1, j) and (i+1, j
+ 1), the percentage of adjacent 8 sites is f(i-1, j-1)、f(i-1, j)、f(i-1, j+1)、f(i, j-1)、f(i, j+1)、f(i+1, j-1)、f(i+1, j)With
f(i+1, j+1), the percentage of site (i, j) is adjusted to f 'E (i, j),
Any site (i, j) in set J, adjacent 8 sites are (i-1, j-1), (i-1, j), (i-1, j+1), (i, j-
1) percentage of, (i, j+1), (i+1, j-1), (i+1, j) and (i+1, j+1), adjacent 8 sites are f(i-1, j-1)、f(i-1, j)、
f(i-1, j+1)、f(i, j-1)、f(i, j+1)、f(i+1, j-1)、f(i+1, j)And f(i+1, j+1), the percentage of site (i, j) is adjusted to f 'J (i, j)：
(3), after the completion of site movement and dot percentage adjust, the encrypted tunnel half tone image with anti-counterfeiting information is obtained；
Step 4: image synthesizes
It is remaining that the encrypted tunnel half tone image with anti-counterfeiting information that step 3 obtains is copied into step 2 blank image
In Color Channel, the original copy half tone image for being embedded with anti-counterfeiting information is obtained, completes encryption.
2. the encryption method of highly concealed type image false-proof information according to claim 1, it is characterised in that：The step 2
In, screening parameter includes 4 screen angles, respectively 0 °, 15 °, 45 ° and 75 °, to encrypted tunnel and 3 Common passageway difference
Digital screening processing is carried out, the screen angle of encrypted tunnel is 0 °, and the screen angle of 3 Common passageways is 15 °, 45 ° and 75 ° three
The arbitrary combination of person.
3. the encryption method of highly concealed type image false-proof information according to claim 2, it is characterised in that：The step 2
In, digital screening processing and newly-built blank image are all made of photoshop softwares, original copy are opened in photoshop, by original copy
Tetra- Color Channel patterns of C, M, Y, K are set as, setting C-channel is as encrypted tunnel, and M, Y, K channel are as Common passageway, first
Color Channel is converted into bitmap, output resolution ratio is arranged in when conversion, then adjusts screen to distinguish each Color Channel using half
Screening processing is carried out, screening parameter further includes dot shape and screen frequency, and dot shape is round or rectangular, screen frequency
For 50~200lpi, the resolution ratio of the blank image is identical with the output resolution ratio.
4. the encryption method of highly concealed type image false-proof information according to claim 2, it is characterised in that：The step 2
In, digital screening processing and newly-built blank image are all made of photoshop softwares, original copy are opened in photoshop, by original copy
Tetra- Color Channel patterns of C, M, Y, K are set as, setting C-channel is as encrypted tunnel, and M, Y, K channel are as Common passageway, first
Four Color Channels are respectively converted into bitmap, output resolution ratio is set when converting into 768dpi, then adjusts screen pair using half
Each Color Channel carries out screening processing respectively, and screening parameter further includes dot shape and screen frequency, and dot shape is circle,
Screen frequency is 96lpi, and the resolution ratio of the blank image is identical with the output resolution ratio.
5. the encryption method of highly concealed type image false-proof information according to claim 1, it is characterised in that：The step 4
Further include making corresponding digital solution chip, production method is after completing encryption：Using the linear grating of digital file format
As digital solution chip, linear grating is rearranged by color lump on the spot and Transparent color block gap, and color lump and transparent color lump are equal on the spot
For the identical rectangular configuration of length, the width of color lump and transparent color lump on the spot is calculated, digital solution chip is obtained, by digital solution chip
It is embedded on the original copy half tone image of anti-counterfeiting information described in being covered in, rotation and mobile digital solution chip are until observe anti-fake
Information completes decoding.
6. the encryption method of highly concealed type image false-proof information according to claim 5, it is characterised in that：The step 5
In, document color lump width be T1, the width of transparent color lump is T2, note screen frequency is L, T1+T2=25.4/L.
7. the encryption method of highly concealed type image false-proof information according to claim 6, it is characterised in that：The step 5
In, the computational methods of color lump width are on the spot：
The image region of a rectangle is selected on encrypted tunnel half tone image, image region is by encrypting constituency and comparison constituency
Composition, encryption constituency are located at the middle of image region and account for the 50~80% of image region；
Measure the dot percentage f of each site in comparison constituency(i, j), the site with maximum value is obtained, on the spot the width of color lump
Spend T1Equal to the height of the site.
8. the encryption method of highly concealed type image false-proof information according to claim 7, it is characterised in that：
The step 4 further includes that will be embedded with the original copy half tone image the output for printing of anti-counterfeiting information, is controlled and is exposed by computer
Light output is made film and shines seal carving version again at printing plate, or correspondence, and the original copy for obtaining being embedded with anti-counterfeiting information is in kind；
The step 5 further includes that digital solution chip is prepared into corresponding grating in kind, and grating in kind is covered in original copy material object
On, until observing anti-counterfeiting information, completion decodes for rotation and moving object grating.
9. the encryption method of highly concealed type image false-proof information according to claim 1, it is characterised in that：The step 3
In, the dot percentage for encrypting site in constituency is no more than 50%.
10. the encryption method of highly concealed type image false-proof information according to claim 1, it is characterised in that：The step
In three, the preparation method for encrypting constituency is：Encrypted tunnel half tone image is opened in photoshop, obtains encrypted tunnel half
Then the figure layer of tone images creates figure layer and is placed into anti-counterfeiting information, obtains anti-counterfeiting information figure layer, choose the wheel of anti-counterfeiting information
Then exterior feature deletes anti-counterfeiting information figure layer, obtains profile constituency, profile constituency is adjusted so that the site in constituency is
Complete site, the profile constituency obtained after adjustment are to encrypt constituency.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060170974A1 (en) * | 2005-01-28 | 2006-08-03 | Hsi-Chun Wang | Method of watermark with hybrid halftone dots |
| CN103996166A (en) * | 2014-06-05 | 2014-08-20 | 上海理工大学 | Holographic anti-counterfeiting algorithm based on shape of screen dot |
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2018
- 2018-04-18 CN CN201810345906.5A patent/CN108551539A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060170974A1 (en) * | 2005-01-28 | 2006-08-03 | Hsi-Chun Wang | Method of watermark with hybrid halftone dots |
| CN103996166A (en) * | 2014-06-05 | 2014-08-20 | 上海理工大学 | Holographic anti-counterfeiting algorithm based on shape of screen dot |
Non-Patent Citations (1)
| Title |
|---|
| 王天马: "基于相位调制法的光栅防伪技术的研究", 《中国优秀硕士学位论文全文数据库 工程科技Ⅱ辑》 * |
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