CN108846788A - It is a kind of improve information extraction performance anti-counterfeit recognition grating angle determine method - Google Patents
It is a kind of improve information extraction performance anti-counterfeit recognition grating angle determine method Download PDFInfo
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- CN108846788A CN108846788A CN201810512567.5A CN201810512567A CN108846788A CN 108846788 A CN108846788 A CN 108846788A CN 201810512567 A CN201810512567 A CN 201810512567A CN 108846788 A CN108846788 A CN 108846788A
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- G—PHYSICS
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- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0021—Image watermarking
Abstract
The invention discloses a kind of anti-counterfeit recognition grating angles for improving information extraction performance to determine method, includes the following steps：Step 1: setting host image and determining hidden area；Step 2: host image halftone process；Step 3: anti-counterfeiting information is hidden；Step 4: the identification of anti-counterfeiting information.The position of phase-modulation of the present invention is more various more flexible, and recognition methods is more scientific, and the concealment of anti-counterfeiting information is higher.
Description
Technical field
The invention belongs to grating field of anti-counterfeit technology, and in particular to a kind of anti-counterfeit recognition grating for improving information extraction performance
Angle determination method.
Background technique
The limit resolution capability of human eye normal vision is limited, the size of dot of image after digital screening and site
When spacing is less than the limit resolution capability of human eye vision, human eye cannot distinguish site.So the binary map of actually discretization
It is discontinuous when picture, but due to human-eye visual characteristic, gone if seeing with certain viewing distance, cannot distinguish between site at all,
It namely cannot distinguish between image detail, the image effect finally continuously adjusted to people's one kind, to realize the printing of continuous tone
Duplication.
It is anti-counterfeiting technology that halftone screen technology and Moire effect combine generation that grating is anti-fake, by half tone image
As soon as several rows of site regards the straight line of rule black as, then energy after the digital raster of itself and same period and width is overlapped
Longitudinal Moire fringe of period infinity is formed, digital raster is exactly to simulate black-white grating optical characteristics on computers and design
A kind of digital raster.Black-white grating is made of largely very subtle chequered with black and white parallel stripes.Ideal situation
Lower black streaking should ensure that completely opaque, that is, light transmittance is zero, informal voucher line i.e. slit, light transmittance 100%.
Most common phase modulation during grating is anti-fake is completed by the position of changing section site, all quilts
Site after movement integrally constitutes new hiding information pattern, is that a kind of that the anti-counterfeiting information that is embedded in will be needed to be hidden will be hidden
Algorithm is hidden, it is whole after carrying out am screening processing to halftoning host's figure due to this low-frequency filter characteristics of human eye vision
The part dot location of structural reform change regional area is that will not significantly cause people behind its micro position since site is very small
Eye is to feel perception, hiding information is embedded among host image based on this principle, and will not cause the sense of human eye vision
Know；Then corresponding grating is utilized, can just be shown when to steganographic detection all by the entire hiding of mobile site composition
Information.
The algorithmic formula of phase modulation is：Wherein, X and Y respectively indicate site laterally and
Longitudinal displacement, D represent the distance between two sites, i.e., the practical distance moved in site is D/2, and mobile direction is
Screen angle direction, unit mm, since screen frequency certainly will be arranged in image halftoning process, D is known to one
Numerical value,
Although phase modulation, using very universal, there is also following deficiencies：
(1), the stage is hidden in anti-counterfeiting information, when dot percentage is more than 20%, net can be generated using phase modulation
Point overlap joint problem, causes visual perception, concealment is lower；
(2), site shift position is limited.
Summary of the invention
The object of the present invention is to provide a kind of anti-counterfeit recognition grating angles for improving information extraction performance to determine method, phase
The position of modulation is more various more flexible, and recognition methods is more scientific, and the concealment of anti-counterfeiting information is higher.
The present invention provides the following technical solutions：A kind of anti-counterfeit recognition grating angle improving information extraction performance is determining
Method includes the following steps：
Step 1: setting host image and determining hidden area
Host image is set, host image is the digital document being made of m*n pixel, and has 4 Color Channels,
Color Channel is made of C-channel, the channel M, the channel Y and K channel；
There is the hidden area that anti-counterfeiting information can be set, hidden area has s*s at least one channel of host image
A pixel, s are respectively less than m and n, and the channel where hidden area is mother matrix, and remaining channel is 3 secondary versions, determine on mother matrix
The position of hidden area remembers that color value of all pixels point of hidden area on mother matrix is identical, is denoted as α, and the range of α is 0.1
~0.5；
Step 2: host image halftone process
Screening parameter is respectively set to 4 channels and carries out screening processing, screening processing adjusts screen, screening parameter packet using half
Output resolution ratio, screen frequency, dot shape and screen angle are included, when carrying out screening processing respectively to 4 channels, use is identical
Output resolution ratio, screen frequency and dot shape, dot shape is circle, and screen angle is 0 °, 15 °, 45 ° and 75 °
Any combination obtains the mother matrix half-tone picture being made of site and 3 width pair version half-tone pictures；
Step 3: anti-counterfeiting information is hidden
It chooses and needs hiding anti-counterfeiting information, mother matrix half-tone picture is opened in image processing software, according to anti-counterfeiting information
Profile establish site constituency in corresponding hidden area, remember that the site in the constituency of site is set A, by the site of set A
Carry out phase-modulation；
The method of phase-modulation is：The mobile identical angle and distance in all sites of set A, remembers any in set A
Site a establishes polar coordinates by pole of the central point q of site a, and the position of the mobile rear center's point of site a is q ', and the pole of q ' is sat
It is designated as (ρ, γ), q ' is any point on polar equation ρ, and the value of ρ is the mobile distance of site a, after γ is site a mobile
Central point and it is mobile before central point line and horizontal line between angle；
After the completion of phase-modulation, obtain the mother matrix half-tone picture for carrying anti-counterfeiting information, by its with 3 width pair version half-tone pictures into
The synthesis of row image obtains the host image half-tone picture for carrying anti-counterfeiting information；
Step 4: the identification of anti-counterfeiting information
Production identification grating：The identification grating for preparing digital document form identifies that the area of grating is greater than hidden area
Area, identification grating is parallel to each other to be alternatively arranged by the identical blackstreak of length and transparent stripe to be formed, the width of blackstreak
Degree is T1, the width of transparent stripe is T2, wherein
Identify anti-counterfeiting information：It will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation is known
Then other grating is moved forward and backward identification grating along the direction β so that the angle between identification grating and horizontal line is β, until set
The site of A and identification grating are formed, and there is the anti-counterfeiting information of powerful contrast to remember the mother matrix to complete the identification of anti-counterfeiting information
Screen angle be θ, the determination method of angle β is：
WhenWhen, β=θ；
WhenWhen ,+90 ° of β=θ.
It is as above-mentioned technical proposal to further describe：
Remember that the screen frequency is l, polar equation ρ is：
It is as above-mentioned technical proposal to further describe：
In step 3, the method for building up in site constituency is：
(1), in photoshop software, new image one, the length and width of image one and the length and width of host image are identical, figure
The input resolution ratio of picture one is identical with the output resolution ratio, and background content is white, and " figure layer 0 " is obtained in figure layer channel,
The mother matrix half-tone picture is copied into image one, is obtained " figure layer 1 ", replicates " figure layer 1 ", obtains " figure layer 2 "；By " figure layer 2 ",
" figure layer 1 " and " figure layer 0 " is sequentially arranged in figure layer window；
(2), " figure layer 3 " is created, " figure layer 3 ", " figure layer 2 ", " figure layer 1 " and " figure layer 0 " is sequentially arranged in figure layer window
In, it is placed in anti-counterfeiting information in " figure layer 3 ", anti-counterfeiting information is moved to the corresponding position of hidden area, " figure layer 3 " is chosen, makes
Anti-counterfeiting information is chosen with magic wand menu, obtains site constituency, setting " figure layer 3 " is invisible.
It is as above-mentioned technical proposal to further describe：
In the step 2, host image halftone process is completed in photoshop software, is beaten in photoshop
Host image is opened, the screening processing adjusts screen using half in photoshop；
The method that each channel carries out screening processing is：Channel is chosen, channel is converted into bitmap, when conversion described in setting
Then output resolution ratio adjusts screen to the processing of channel screening using half, the screen frequency is 90~200lpi.
It is as above-mentioned technical proposal to further describe：
The screen angle θ of the mother matrix is 0 °, any combination that the screen angle of 3 secondary versions is 15 °, 45 ° and 75 °.
It is as above-mentioned technical proposal to further describe：
In the step 4, the determination method of angle β is：
WhenWhen, β=θ；
WhenWhen ,+90 ° of β=θ.
It is as above-mentioned technical proposal to further describe：
It further include that will be embedded with the host image half-tone picture the output for printing for carrying anti-counterfeiting information in the step 3, print
Before brushing output, the setting identification label on host image half-tone picture identifies and is labeled as cross-shaped structure, the one of cross-shaped structure
Angle between side and horizontal line is β, then controls exposure output by output equipment and film is made at printing plate, or correspondence
Seal carving version is shone again, and the host image for obtaining carrying anti-counterfeiting information is in kind；
It further include that the identification grating of digital document form is prepared into corresponding grating in kind in the step 4, it will be real
Object light grid are covered on host image material object, are marked according to identification and are rotated grating in kind so that the blackstreak of grating in kind or
Person's transparent stripe and horizontal angle are β, are then moved forward and backward grating in kind along the direction β, until observe anti-counterfeiting information, it is complete
At identification.
It is as above-mentioned technical proposal to further describe：
In the step 3, image synthetic method is：
New image two in photoshop, the length and width of image two and the length and width of host image are identical, the input of image two
Resolution ratio is identical with the output resolution ratio, and background content is white, and color mode is CMKY mode, by the mother matrix halftoning
Figure and 3 width pair version half-tone pictures be copied into corresponding Color Channel to get.
It is as above-mentioned technical proposal to further describe：
The output resolution ratio is the integral multiple of screen frequency.
It is as above-mentioned technical proposal to further describe：
The output resolution ratio is 2400dpi, screen frequency 96lpi.
It is as above-mentioned technical proposal to further describe：
The output resolution ratio is 1440dpi, screen frequency 96lpi.
Beneficial effects of the present invention：The position of phase-modulation is more various more flexible, and recognition methods is more scientific, anti-counterfeiting information
Concealment is higher, specific as follows：
1, step one of the invention can determine color value of the hidden area on Color Channel, in halftone process,
Color value α corresponds to the dot percentage of site, indirectly determines the distance that site is displaced in phase modulation process, step
One has determined the data such as the color mode of host image and image size, further defines the specific location of mother matrix, hidden area,
Host image is opened in photoshop, observation colouring information finds corresponding hidden area, easy to operate；Host image can be with
It is the original copy directly made in image processing software, is also possible to the qualified original copy randomly selected, the scope of application is more
Extensively, more flexible；
2, step 1 of the present invention, α only consider 0.1~0.5 range, because in actual operation, surveying by many experiments
Examination discovery, when dot percentage is less than 0.1, the concealment of anti-counterfeiting information is very good, but it is very poor to extract recognition performance；Work as net
When point percentage is greater than 0.5, the extraction recognition performance of anti-counterfeiting information is preferable, but concealment is weaker, best hidden to reach
Property and extractability, in addition, in actual operation, when dot percentage reaches 0.5, using the halftoning after photoshop screening
In figure (dot shape is circle), two neighboring site has contacted with each other the case where not generating displacement, can not carry out phase
Modulation, the conspicuousness at edge is clearly；
3, step three of the invention, the low-frequency filter characteristics based on human eye vision are carrying out am screening processing to original copy
Afterwards, the dot location for changing regional area in mother matrix carries out phase-modulation, and anti-counterfeiting information is embedded into host image, reaches anti-
The hiding purpose of fake information；Advantage compared with prior art is：
(1), in the prior art, the phase modulation of site displacement is in order to realize Moire effect, it is contemplated that all sites into
The identical displacement of row, but for borderline part site, practical movably distance is between two site closest approaches
Distance is denoted as D1, in the state of the art, relevant deeply grind there has been no the movable distance to boundary node
Studying carefully, seldom some are also limited in the subjective judgement and theoretical basis of shallow-layer, according to site displacement method, all sites movements
Distance is D/2, and moving direction is the direction (i.e. along the cable direction of formation) of screen angle, finds in the present invention, works as D/2=
D1When, the site after moving at this time is just in contact with the site in front of it but does not overlap, due to meeting in halftone process early period
Screening parameter is set, therefore screen frequency is datum, screen frequency has determined the distance between two neighboring site D and one
The side length D of mesh tune unit2, D=D2, the distance between two site closest approaches D1Equal to the distance between two neighboring site D
The value for subtracting two radius r, in the case where screen frequency is certain, D1Site radius r is then depended on, and site radius depends on
Dot percentage α (i.e. the corresponding color value of pixel on channel), obtains following formula：
Therefore, when D/2 is equal to D1When,Site after moving at this time is just in contact with the site in front of it but not
Overlap joint；In the prior art, there has been no research in view of this threshold value influences site displacement method bring；
When site mobile according to site displacement method, borderline part site can take with the site in front of its moving direction
Connect, site overlap joint can cause very big counter productive to anti-counterfeiting information concealment, the visual perception of lap-joint clearly, especially
It is the site or borderline site of lap-joint, and the profile of anti-counterfeiting information can be made just to be perceived by the human eye before extraction, led
Cause antiforge function failure；Therefore, in the present invention, only it is less than or equal in αWith reference to existing site displacement method；
When α is greater than(the mobile D/2 on screening direction), site choosing when site mobile according to traditional site displacement method
Site in front of the borderline part site in area and its moving direction overlaps, and site overlap joint can cause anti-counterfeiting information concealment non-
Often big counter productive, the visual perception of lap-joint clearly, the especially site of lap-joint or borderline site, meeting
So that the profile of anti-counterfeiting information is just perceived by the human eye before extraction, antiforge function is caused to fail；To guarantee certain concealment, together
When guarantee again borderline site can for extract identity contribute, when site moving distance S be maximum distance D1When, it mentions
Performance is taken to reach most preferably, it is specific as follows：
S=D1；
And because：
So
(2), in the prior art, the moving direction of phase modulation site be only along screen angle direction front and back or hang down
Directly in the front and back in screen angle direction, in conjunction with moving distance, the last shift position in site is only this at 4, and the present invention is directed toHidden area each site, moveable position be a circular trace, with the center of circle of original site
For the center of circle of circular trace, using D/2 as the radius of circular trace, polar equation is：Such move mode can
To ensure that site phase-modulation still has good extraction performance and concealment in the case where as small as possible；ForHidden area each site, moveable position is also a circular trace, with the circle of original site
The heart is the center of circle of circular trace, with D1For the radius of circular trace, polar equation is：
4, step four of the invention designs different grating identification for different phase-modulation angles in conjunction with step 3
Angle, β are 90 ° or 0 °, between the line and horizontal line in the center of circle when center of circle and home position after the site of set A is mobile
Angle be Ω, the present invention hides the angular dimension of the Ω in stage according to anti-counterfeiting information early period, studies it to cognitive phase grating
Influence, the angular dimension of Ω is classified, allow to identification when have corresponding grating identify angle；
5, step three of the invention further includes that will be embedded with the host image half-tone picture the output for printing for carrying anti-counterfeiting information,
Before the output for printing, setting identification label, identification are labeled as cross-shaped structure on host image half-tone picture, cross-shaped structure
The angle between horizontal line is β on one side, and step 4 further includes that the identification grating of digital document form is prepared into corresponding reality
Object light grid, identification label play indicative function, do not influence antiforge function, can aspect user's verifying anti-counterfeiting information.
Detailed description of the invention
Attached drawing is used to provide further understanding of the present invention, and constitutes part of specification, with reality of the 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 host image in the embodiment of the present invention 1 (color information is not shown)；
The schematic diagram that Fig. 2 is site a on mother matrix in the embodiment of the present invention 1 (site is set as hollow in order to facilitate observation of)；
Fig. 3 is schematic diagram (the site setting in order to facilitate observation of of site a moveable position on mother matrix in the embodiment of the present invention 1
It is hollow)；
Fig. 4 is the mother matrix half-tone picture in the embodiment of the present invention 1；
Fig. 5 is the host image half-tone picture that anti-counterfeiting information is carried in the embodiment of the present invention 1 (color information is not shown)；
Fig. 6 is that mother matrix screen angle and identification grating angle when being 0 ° in the embodiment of the present invention 1, site displacement are modulated
The schematic diagram of range；
Fig. 7 is the host image half-tone picture in the embodiment of the present invention 1 after covering identification grating (color information is not shown)；
Fig. 8 is the host image in the embodiment of the present invention 2 (color information is not shown)；
Fig. 9 is the mother matrix half-tone picture in the embodiment of the present invention 2；
Figure 10 is the host image half-tone picture that anti-counterfeiting information is carried in the embodiment of the present invention 2 (color information is not shown)；
Figure 11 for the host image half-tone picture after covering identification grating in the embodiment of the present invention 2, (do not show by color information
Out)；
Figure 12 is the host image in the embodiment of the present invention 3 (color information is not shown)；
Figure 13 is the mother matrix half-tone picture in the embodiment of the present invention 3；
Figure 14 is the host image half-tone picture that anti-counterfeiting information is carried in the embodiment of the present invention 3 (color information is not shown)；
Figure 15 for the host image half-tone picture after covering identification grating in the embodiment of the present invention 3, (do not show by color information
Out)；
Figure 16 is the host image in the embodiment of the present invention 4 (color information is not shown)；
Figure 17 is the mother matrix half-tone picture in the embodiment of the present invention 4；
Figure 18 is the host image half-tone picture that anti-counterfeiting information is carried in the embodiment of the present invention 4 (color information is not shown)；
Figure 19 for the host image half-tone picture after covering identification grating in the embodiment of the present invention 4, (do not show by color information
Out)；
Figure 20 is schematic diagram in the present invention on mother matrix after site a moveable position and identification grating covering (for convenient for seeing
It examines site and is set as hollow, identification grating blackstreak as transparent linear)；
Figure 21 is the schematic diagram that site is displaced modulated range when mother matrix screen angle of the present invention is not equal to 0；
Figure 22 is the partial enlargement diagram of Figure 21 of the present invention；
Specific embodiment
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.Now in conjunction with Figure of description, the design feature that the present invention will be described in detail.
Embodiment 1
It is a kind of improve information extraction performance anti-counterfeit recognition grating angle determine method, include the following steps：
Step 1: selection host image and determining hidden area
Selection needs to carry out the hiding host image of anti-counterfeiting information, and the condition that host image need to meet is：
(1), it is made of m*n pixel, tiff format and color mode are CMYK (i.e. by C-channel, the channel M, the channel Y
It is formed with K channel)；
(2), there is the hidden area that anti-counterfeiting information can be set, hidden area tool at least one channel of host image
There is s*s pixel, s is respectively less than m and n, and the channel where hidden area is mother matrix, and remaining channel is 3 secondary versions, on mother matrix
The position for determining hidden area remembers that color value of all pixels point of hidden area on mother matrix is identical, is denoted as α, the range of α is
0.1~0.5；
In this implementation, what is obtained meets the input resolution ratio of the host image of condition for 2400lpi, m=n=3780, s=
1260, the length and width of host image are 4cm, and the value of α is 0.15 in obtained hidden area；
Step 2: host image halftone process
Host image is opened in photoshop, screening processing adjusts screen using half in photoshop；To 4 channels
Screening parameter is respectively set and carries out screening processing, screening processing adjusts screen using half, and screening parameter includes output resolution ratio, screening
Line number, dot shape and screen angle, when carrying out screening processing respectively to 4 channels, using identical output resolution ratio, screening
Line number and dot shape, dot shape are circle, in this implementation screen frequency be 96lpi, output resolution ratio 2400dpi,
The screen angle θ of mother matrix is 0 °, any combination that the screen angle of 3 secondary versions is 15 °, 45 ° and 75 °；θ is 0 ° in the present embodiment
The difficulty of hiding anti-counterfeiting information can be reduced；
Wherein, the method for each channel progress screening processing is：Channel is chosen, channel is converted into bitmap, when conversion sets
Setting the output resolution ratio is 2400dpi, then adjusts screen to the processing of channel screening using half according to aforementioned screening parameter；It obtains
The mother matrix half-tone picture and 3 width pair version half-tone pictures be made of site；
Step 3: anti-counterfeiting information is hidden
It chooses and needs hiding anti-counterfeiting information, in the present embodiment, anti-counterfeiting information is figure and literary combinatorics on words, according to its wheel
Exterior feature establishes site constituency in corresponding hidden area, and the method for establishing site constituency is：
(1), in photoshop software, new image one, the length and width of image one and the length and width of host image are identical, i.e.,
Length and width are 4cm, and the input resolution ratio of image one is 2400dpi, and background content is white, obtain " figure layer in figure layer channel
0 ", the mother matrix half-tone picture is copied into image one, is obtained " figure layer 1 ", replicates " figure layer 1 ", obtains " figure layer 2 "；By " figure layer
2 ", " figure layer 1 " and " figure layer 0 " is sequentially arranged in figure layer window；
(2), " figure layer 3 " is created, " figure layer 3 ", " figure layer 2 ", " figure layer 1 " and " figure layer 0 " is sequentially arranged in figure layer window
In, it is placed in anti-counterfeiting information in " figure layer 3 ", anti-counterfeiting information is moved to the corresponding position of hidden area, " figure layer 3 " is chosen, makes
Anti-counterfeiting information is chosen with magic wand menu, obtains site constituency, then setting " figure layer 3 " is invisible, " figure layer 2 " is chosen, at this point, net
The site that point constituency is chosen out in " figure layer 2 " is the site for needing to carry out phase-modulation, is denoted as set A；
Such phase modulation method be：The mobile identical angle and distance in all sites of set A, remembers in set A
Any site a, by taking a of the site as an example, the modulator approach of remaining site is identical, referring to figs. 2 and 3, with the central point of site a
Q is that pole establishes polar coordinates, and the position of the mobile rear center's point of site a is q ', and the polar coordinates of q ' are (ρ, γ), and ρ is mobile for site a
Distance, γ is the angle between the line and horizontal line of the central point in the central point after site is mobile and home position, and q ' is
Any point on polar equation ρ, the moveable position of q ' is the dashed trace formd in Fig. 2, after remembering screening, adjacent two
The distance between a site be D (in known in this field,), dashed trace is circle, and its radius is equal to D/2, because
This, the polar equation of dashed trace is：Site a is moved to any point in dashed trace, it can be real
The hiding and identification of existing anti-counterfeiting information；
After the completion of phase-modulation, obtain the mother matrix half-tone picture for carrying anti-counterfeiting information, by its with 3 width pair version half-tone pictures into
The synthesis of row image, new image two in photoshop, the length and width of image two and the length and width of host image are identical, image two
It is identical with the output resolution ratio to input resolution ratio, background content is white, and color mode is CMKY mode, by the mother matrix half
Tone illustration and 3 width pair version half-tone pictures are copied into corresponding Color Channel, referring to Fig. 5, obtain the host for carrying anti-counterfeiting information
Image half-tone picture completes hiding for anti-counterfeiting information；
Step 4: the identification of anti-counterfeiting information
Production identification grating：The identification grating for preparing digital document form identifies that the area of grating is greater than hidden area
Area, identification grating is parallel to each other to be alternatively arranged by the identical blackstreak of length and transparent stripe to be formed, the width of blackstreak
Degree is T1, the width of transparent stripe is T2(in known in this field,)；
T1Determination method be：To form Moire fringe, T is designed1=2r, so that during the extraction process, presenting a contrast and making
Anti-counterfeiting information shows, r represents the radius of site, and becauseTherefore T1=2r is equivalent to：
To further,The width of identification grating blackstreak and transparent stripe has been determined with this；
Identify anti-counterfeiting information：It will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation is known
Then other grating is moved forward and backward identification grating along the direction β so that the angle between identification grating and horizontal line is β, until set
The site of A and identification grating form the anti-counterfeiting information with powerful contrast, to complete the identification of anti-counterfeiting information, obtain extracting anti-
The stacking chart of the identification grating and host image half-tone picture of fake information, the determination method of angle β are：
(1), referring to Fig. 6, when Fig. 6 is that mother matrix screen angle and identification grating angle are 0 ° in the embodiment of the present invention 1, net
Point is displaced the schematic diagram of modulated range；When the center of circle q displaced position of site a is q ' in Fig. 3,4 positions shown in h1, h2 and h3
When setting, in the identification anti-counterfeiting information stage, at this 4 positions, it is mobile after site with angle be that 0 ° of identification grating is just tangent,
When it continues mobile close to identification grating, use angle for 90 ° of identification grating after its to extract resolution higher；
(2), when remembering tangent, the angle between the line and screen angle direction of the center of circle q ' and q is Ω, the center of circle h1's and q
Angle between line and screen angle direction is Ω 1, and the angle between the line and screen angle direction of the center of circle h2 and q is Ω
2, the angle between the line and screen angle direction of the center of circle h3 and q is Ω 3；Again because aforementioned, γ is the circle after site is mobile
Angle between the heart and the circular line and horizontal line in home position, in the present embodiment, screen angle is 0 °, therefore, corresponding
, as Ω≤γ≤Ω1Or Ω2≤γ≤Ω3When, use angle β to be identified for 0 °, remaining section then uses angle β
It is identified for 90 °；
(3), further, referring to Fig. 3, the calculation method of Ω is as follows：
Then correspondence calculates Ω1、Ω2、Ω3, obtain the determination method of following angle β：
WhenWhen, β=0 °；
WhenWhen, β=90 °.
Furtherly,
It further include that will be embedded with the host image half-tone picture the output for printing for carrying anti-counterfeiting information in the step 3, print
Before brushing output, the setting identification label on host image half-tone picture identifies and is labeled as cross-shaped structure, the one of cross-shaped structure
Angle between side and horizontal line is β, then controls exposure output by output equipment and film is made at printing plate, or correspondence
Seal carving version is shone again, and the host image for obtaining carrying anti-counterfeiting information is in kind；
It further include that the identification grating of digital document form is prepared into corresponding grating in kind in the step 4, it will be real
Object light grid are covered on host image material object, are marked according to identification and are rotated grating in kind so that the blackstreak of grating in kind or
Person's transparent stripe and horizontal angle are β, are then moved forward and backward grating in kind along the direction β, until observe anti-counterfeiting information, it is complete
At identification.
Furtherly,
In the present embodiment step 4, the production method for identifying grating is：
(1), photoshop software is opened, figure layer X is created, background colour is set as transparent (no background colour), then the figure built
The first rectangle of a length and width particular value is drawn on layer with the rectangle tool, then Fill Color is (preferably in the rectangle frame finished
Black), then the second rectangle that a width is equal with the first rectangle, length is greater than the first rectangle is drawn in the same way, and
It covers on the first rectangle, the first rectangle is located at the bottom in the second rectangle, then selects " editor/definition pattern ", will be ready-made
Pattern saves as " pattern 0 "；Wherein, the length of the first rectangle is T1, the length of the second rectangle is T1+T2, as mesh tune
The side length of unit, also the distance D between as two neighboring site；
(2), delete layer X, then builds a new figure layer again and be named as figure layer Z, and the size of figure layer Z is to decode straight line
The size of grating, resolution ratio is identical with the output resolution ratio, then using " pattern 0 " saved come Photoshop Z, after filling
Form the identification grating for detecting anti-counterfeiting information.
Concealment evaluation：
The mother matrix half-tone picture of carrying anti-counterfeiting information in embodiment 1 is carried out image with 3 width pair version half-tone pictures to synthesize,
Obtain carrying the host image half-tone picture of anti-counterfeiting information；Using SSIM (structural similarity) algorithm and WSNR (weighted signal-to-noise ratio)
Evaluation is not embedded into the host image half-tone picture of anti-counterfeiting information and carries both host image half-tone pictures of anti-counterfeiting information respectively
Between similarity, to obtain the concealed evaluation result of hiding information indirectly, as shown in table 1 below：
1 embodiment of table, 1 similarity evaluation result
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 value of embodiment 1 is close to 1, and WSNR is larger, therefore method of the invention, concealment effect is good, no
Easily it is detected by human eye.
Extract identity evaluation：
Using region contrast function FiWith comentropy function algorithm Ti, the value of the two algorithms be all between 0 and 1 it
Between numerical value, FiAnd TiValue closer to 1, the background reflectance for representing security pattern and host image that grating identifies is bigger, figure
As more clear significant：
(1), region contrast function Fi
Above formula is the saliency evaluation function based on region contrast, and dev (x, y) indicates region pair defined above
Degree of ratio；maxfΔ(x, y) and minfΔ(x, y) respectively represents gray scale maximum value and minimum value in the region, 0≤dev (x, y)
≤1；
(2), comentropy function algorithm Ti
Above formula is information entropy function, pkIndicate the frequency that gray value k occurs in the images, N indicates the gray scale etc. of image
Grade.
Using region contrast function FiWith comentropy function algorithm TiRespectively evaluation extract anti-counterfeiting information identification grating and
The stacking chart of host image half-tone picture, obtained result are as shown in table 2 below：
2 embodiment 1 of table extracts identity evaluation result
Wherein, FiAnd TiValue closer to 1, the background reflectance for representing security pattern and host image that grating identifies is got over
Greatly, image is more clear significant, the F of embodiment 1iAnd TiValue be all larger than 0.5, therefore method of the invention, extract recognition performance
It is good.
Embodiment 2
Referring to Fig. 8~11, on the basis of embodiment 1, embodiment 2 the difference is that：(1), host image is different；
(2), anti-counterfeiting information is text；(3), 0.1 α；
Concealment evaluation：
The mother matrix half-tone picture of carrying anti-counterfeiting information in embodiment 2 is carried out image with 3 width pair version half-tone pictures to synthesize,
Obtain carrying the host image half-tone picture of anti-counterfeiting information；Using SSIM (structural similarity) algorithm and WSNR (weighted signal-to-noise ratio)
Evaluation is not embedded into the host image half-tone picture of anti-counterfeiting information and carries both host image half-tone pictures of anti-counterfeiting information respectively
Between similarity, to obtain the concealed evaluation result of hiding information indirectly, as shown in table 3 below：
3 embodiment of table, 2 similarity evaluation result
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 3 is stated it is found that the SSIM value of embodiment 2 is close to 1, and WSNR is larger, therefore method of the invention, concealment effect is good, no
Easily it is detected by human eye.
Extract identity evaluation：
Using region contrast function FiWith comentropy function algorithm Ti, the identification grating of anti-counterfeiting information is extracted in evaluation respectively
With the stacking chart of host image half-tone picture, obtained result is as shown in table 4 below：
4 embodiment 2 of table extracts identity evaluation result
Wherein, FiAnd TiValue closer to 1, the background reflectance for representing security pattern and host image that grating identifies is got over
Greatly, image is more clear significant, the F of embodiment 1iAnd TiValue be all larger than 0.5, therefore method of the invention, extract recognition performance
It is good.
Embodiment 3
Referring to Figure 12~15, on the basis of embodiment 1, embodiment 3 the difference is that：(1), host image is not
Together；(2), anti-counterfeiting information is figure；(3), 0.25 α；
Concealment evaluation：
The mother matrix half-tone picture of carrying anti-counterfeiting information in embodiment 3 is carried out image with 3 width pair version half-tone pictures to synthesize,
Obtain carrying the host image half-tone picture of anti-counterfeiting information；Using SSIM (structural similarity) algorithm and WSNR (weighted signal-to-noise ratio)
Evaluation is not embedded into the host image half-tone picture of anti-counterfeiting information and carries both host image half-tone pictures of anti-counterfeiting information respectively
Between similarity, to obtain the concealed evaluation result of hiding information indirectly, as shown in table 5 below：
5 embodiment of table, 3 similarity evaluation result
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 5 is stated it is found that the SSIM value of embodiment 3 is close to 1, and WSNR is larger, therefore method of the invention, concealment effect is good, no
Easily it is detected by human eye.
Extract identity evaluation：
Using region contrast function FiWith comentropy function algorithm Ti, the identification grating of anti-counterfeiting information is extracted in evaluation respectively
With the stacking chart of host image half-tone picture, obtained result is as shown in table 6 below：
6 embodiment 3 of table extracts identity evaluation result
Wherein, FiAnd TiValue closer to 1, the background reflectance for representing security pattern and host image that grating identifies is got over
Greatly, image is more clear significant, the F of embodiment 3iAnd TiValue be all larger than 0.5, therefore method of the invention, extract recognition performance
It is good.
Embodiment 4
Referring to Figure 16~19, on the basis of embodiment 1, embodiment 4 the difference is that：(1), host image is not
Together；(2), anti-counterfeiting information is text；(3), 0.3 α；
Concealment evaluation：
The mother matrix half-tone picture of carrying anti-counterfeiting information in embodiment 4 is carried out image with 3 width pair version half-tone pictures to synthesize,
Obtain carrying the host image half-tone picture of anti-counterfeiting information；Using SSIM (structural similarity) algorithm and WSNR (weighted signal-to-noise ratio)
Evaluation is not embedded into the host image half-tone picture of anti-counterfeiting information and carries both host image half-tone pictures of anti-counterfeiting information respectively
Between similarity, to obtain the concealed evaluation result of hiding information indirectly, as shown in table 7 below：
7 embodiment of table, 4 similarity evaluation result
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 7 is stated it is found that the SSIM value of embodiment 4 is close to 1, and WSNR is larger, therefore method of the invention, concealment effect is good, no
Easily it is detected by human eye.
Extract identity evaluation：
Using region contrast function FiWith comentropy function algorithm Ti, the identification grating of anti-counterfeiting information is extracted in evaluation respectively
With the stacking chart of host image half-tone picture, obtained result is as shown in table 8 below：
8 embodiment 4 of table extracts identity evaluation result
Wherein, FiAnd TiValue closer to 1, the background reflectance for representing security pattern and host image that grating identifies is got over
Greatly, image is more clear significant, the F of embodiment 4iAnd TiValue be all larger than 0.5, therefore method of the invention, extract recognition performance
It is good.
In conclusion the determination method of angle β is in the present invention：
(1), referring to fig. 20, in the hiding anti-counterfeiting information stage, the center of circle q displaced position of site a is q ' in Fig. 3, h4, h5 and
In the case where 4 positions shown in h6, the site in the identification anti-counterfeiting information stage, on this 4 positions, after movement can be caused
It is that 0 ° of identification grating is just tangent with angle, if the mobile position in site is continued close to knowledge in the hiding anti-counterfeiting information stage
When other grating is mobile, since the identification grating that can be 0 ° with angle generates lap, so than when use angle for 90 ° of knowledge
It is higher to extract resolution for it after other grating；
(2), referring to fig. 22, when remembering tangent, between the line of the center of circle q ' and q and screen angle direction (i.e. cable direction)
Angle is Ω, and the angle between the line and screen angle direction of the center of circle h4 and q is Ω4, line and the screening angle of the center of circle h5 and q
The angle spent between direction is Ω5, the angle between the line and screen angle direction of the center of circle h6 and q is Ω6；γ is site shifting
Angle between the line and horizontal line of the center of circle q of center of circle q ' and home position after dynamic, it is therefore, corresponding, as Ω-θ≤γ
≤Ω4- θ or-(Ω5+θ)≤γ≤-(Ω6+ θ) when, use angle β to be identified for 0 °, remaining angular interval then uses
Angle β is 90 ° and is identified；
(3), further, the calculation method of 1, Ω is as follows referring to fig. 2：
Then correspondence calculates Ω4、Ω5、Ω6, obtain the determination method of following angle β：When
When, β=θ；
WhenWhen ,+90 ° of β=θ.
Claims (10)
1. a kind of anti-counterfeit recognition grating angle for improving information extraction performance determines method, which is characterized in that include the following steps：
Step 1: setting host image and determining hidden area
Host image is set, and host image is the digital document being made of m*n pixel, and has 4 Color Channels, color
Channel is made of C-channel, the channel M, the channel Y and K channel；
There is the hidden area that anti-counterfeiting information can be set, hidden area has s*s picture at least one channel of host image
Vegetarian refreshments, s are respectively less than m and n, and the channel where hidden area is mother matrix, and remaining channel is 3 secondary versions, determine and hide on mother matrix
The position in region remembers that color value of all pixels point of hidden area on mother matrix is identical, is denoted as α, the range of α is 0.1~
0.5；
Step 2: host image halftone process
Screening parameter is respectively set to 4 channels and carries out screening processing, screening processing adjusts screen using half, and screening parameter includes defeated
Resolution ratio, screen frequency, dot shape and screen angle out, when carrying out screening processing respectively to 4 channels, using identical defeated
Resolution ratio, screen frequency and dot shape out, dot shape are circle, and screen angle is 0 °, 15 °, 45 ° and 75 ° any
Combination, obtains the mother matrix half-tone picture being made of site and 3 width pair version half-tone pictures；
Step 3: anti-counterfeiting information is hidden
It chooses and needs hiding anti-counterfeiting information, mother matrix half-tone picture is opened in image processing software, according to the wheel of anti-counterfeiting information
Exterior feature establishes site constituency in corresponding hidden area, remembers that the site in the constituency of site is set A, the site of set A is carried out
Phase-modulation；
The method of phase-modulation is：The mobile identical angle and distance in all sites of set A, remembers any site in set A
A establishes polar coordinates by pole of the central point q of site a, and the position of the mobile rear center's point of site a is q ', and the polar coordinates of q ' are
(ρ, γ), q ' are any point on polar equation ρ, and the value of ρ is the mobile distance of site a, γ be site a mobile after in
Angle between the line and horizontal line of central point before heart point and movement；
After the completion of phase-modulation, the mother matrix half-tone picture for carrying anti-counterfeiting information is obtained, it is subjected to figure with 3 width pair version half-tone pictures
As synthesis, the host image half-tone picture for carrying anti-counterfeiting information is obtained；
Step 4: the identification of anti-counterfeiting information
Production identification grating：The identification grating for preparing digital document form identifies that the area of grating is greater than the area of hidden area,
Identification grating is parallel to each other to be alternatively arranged by the identical blackstreak of length and transparent stripe to be formed, and the width of blackstreak is
T1, the width of transparent stripe is T2, wherein
Identify anti-counterfeiting information：It will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation identification light
Then grid are moved forward and backward identification grating along the direction β so that the angle between identification grating and horizontal line is β, until set A
Site and identification grating are formed, and there is the anti-counterfeiting information of powerful contrast to remember the mother matrix to complete the identification of anti-counterfeiting information
Screen angle is θ, and the determination method of angle β is：
When
When
2. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：Remember that the screen frequency is l, polar equation ρ is：
3. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：In the step 3, the method for building up in site constituency is：
(1), in photoshop software, new image one, the length and width of image one and the length and width of host image are identical, image one
Input resolution ratio it is identical with the output resolution ratio, background content be white, " figure layer 0 " is obtained in figure layer channel, by institute
It states mother matrix half-tone picture and is copied into image one, obtain " figure layer 1 ", replicate " figure layer 1 ", obtain " figure layer 2 "；By " figure layer 2 ", " figure
Layer 1 " and " figure layer 0 " are sequentially arranged in figure layer window；
(2), " figure layer 3 " is created, " figure layer 3 ", " figure layer 2 ", " figure layer 1 " and " figure layer 0 " is sequentially arranged in figure layer window,
It is placed in anti-counterfeiting information in " figure layer 3 ", anti-counterfeiting information is moved to the corresponding position of hidden area, " figure layer 3 " is chosen, uses magic stick
Tool chooses anti-counterfeiting information, obtains site constituency, and setting " figure layer 3 " is invisible.
4. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：In the step 2, host image halftone process is completed in photoshop software, and host is opened in photoshop
Image, the screening processing adjust screen using half in photoshop；
The method that each channel carries out screening processing is：Channel is chosen, channel is converted into bitmap, the output is arranged in when conversion
Then resolution ratio adjusts screen to the processing of channel screening using half, the screen frequency is 90~200lpi.
5. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：The screen angle θ of the mother matrix is 0 °, any combination that the screen angle of 3 secondary versions is 15 °, 45 ° and 75 °.
6. the anti-counterfeit recognition grating angle according to claim 5 for improving information extraction performance determines that method, feature exist
In：In the step 4, the determination method of angle β is：
When
When
7. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：It further include that will be embedded with the host image half-tone picture the output for printing for carrying anti-counterfeiting information in the step 3, the output for printing
Before, setting identification label, identification are labeled as cross-shaped structure, one side of cross-shaped structure and water on host image half-tone picture
Angle between horizontal line is β, then controls exposure output by output equipment and film is made and shines system again at printing plate, or correspondence
Printing plate, the host image for obtaining carrying anti-counterfeiting information are in kind；
It further include that the identification grating of digital document form is prepared into corresponding grating in kind, by light in kind in the step 4
Grid are covered on host image material object, grating in kind are rotated according to identifying to mark, so that the blackstreak of grating in kind or saturating
Bright fringe and horizontal angle are β, are then moved forward and backward grating in kind along the direction β, until observing anti-counterfeiting information, complete to know
Not.
8. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：In the step 3, image synthetic method is：
New image two in photoshop, the length and width of image two and the length and width of host image are identical, and the input of image two is differentiated
Rate is identical with the output resolution ratio, and background content is white, and color mode is CMKY mode, by the mother matrix half-tone picture and
3 width pair version half-tone pictures be copied into corresponding Color Channel to get.
9. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：The output resolution ratio is the integral multiple of screen frequency.
10. the anti-counterfeit recognition grating angle according to claim 1 for improving information extraction performance determines that method, feature exist
In：The output resolution ratio is 2400dpi, screen frequency 96lpi.
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