CN109159575A - A kind of identification grating angle based on phase modulation determines method - Google Patents
A kind of identification grating angle based on phase modulation determines method Download PDFInfo
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- CN109159575A CN109159575A CN201810560495.1A CN201810560495A CN109159575A CN 109159575 A CN109159575 A CN 109159575A CN 201810560495 A CN201810560495 A CN 201810560495A CN 109159575 A CN109159575 A CN 109159575A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/328—Diffraction gratings; Holograms
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/342—Moiré effects
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T1/00—General purpose image data processing
- G06T1/0021—Image watermarking
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
- G06T2201/00—General purpose image data processing
- G06T2201/005—Image watermarking
- G06T2201/0065—Extraction of an embedded watermark; Reliable detection
Abstract
The invention discloses a kind of identification grating angles based on phase modulation to determine method, includes the following steps: Step 1: host image is arranged and determines 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 identification grating angle based on phase modulation is true
Determine 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 after the digital raster of itself and same period and width is overlapped
Can form longitudinal Moire fringe of period infinity, digital raster be exactly simulate black-white grating optical characteristics on computers and
A kind of digital raster of design.Black-white grating is made of largely very subtle chequered with black and white parallel stripes.It is ideal
In the case of black streaking should ensure that completely opaque, that is, light transmittance is zero, informal voucher line i.e. slit, and light transmittance is
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 the anti-counterfeiting information that is embedded in will be needed to be hidden
Hidden algorithm is carrying out am screening processing to halftoning host's figure due to this low-frequency filter characteristics of human eye vision
Afterwards, the whole part dot location for changing regional area, since site is very small, being behind its micro position will not be apparent
Causing human eye is to feel perception, hiding information is embedded among host image based on this principle, and human eye will not be caused to regard
The perception of feel；Then corresponding grating is utilized, can just be shown when to steganographic detection all by the whole of mobile site composition
A hiding information.
The algorithmic formula of phase modulation are as follows: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
For screen angle direction, unit mm, due to that certainly will be arranged screen frequency in image halftoning process, D be one
Know 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 identification grating angles based on phase modulation to determine method, phase-modulation
Position 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 identification grating angle based on phase modulation determines method,
Include 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, using phase
Same output resolution ratio, screen frequency and dot shape, dot shape are circle, and screen angle is 0 °, 15 °, 45 ° and 75 °
Any combination, obtain 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 net of set A
Point carries out phase-modulation；
The method of phase-modulation are as follows: 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 ', the pole of q '
Coordinate is (ρ, γ), and q ' is any point on polar equation ρ, and the value of ρ is the mobile distance of site a, and γ is site a shifting
Angle between the line and horizontal line of the central point before central point and movement after dynamic；
The method for building up in site constituency are as follows:
(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；
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: preparing the identification grating of 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
Identification 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 collection
The site and identification grating for closing A form the anti-counterfeiting information with powerful contrast, so that the identification of anti-counterfeiting information is completed, described in note
The screen angle of mother matrix is θ, the determination method of angle β are as follows:
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 are as follows:
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 are as follows: choose channel, 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 are as follows:
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 brush output, 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, then controls exposure output by output equipment and phenanthrene is made at printing plate, or correspondence
Forest tract shines seal carving version 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,
Complete identification.
It is as above-mentioned technical proposal to further describe:
In the step 3, image synthetic method are as follows:
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 half color of mother matrix
Change the line map with 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 1920dpi, 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
Rapid one has determined the data such as the color mode of host image and image size, further defines the specific position of mother matrix, hidden area
It sets, host image is opened in photoshop, observation colouring information finds corresponding hidden area, easy to operate；Host's figure
As can be the original copy directly made in image processing software, being also possible to the qualified original copy randomly selected, being applicable in
Range is wider, 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；When
When dot percentage is greater than 0.5, the extraction recognition performance of anti-counterfeiting information is preferable, but concealment is weaker, best hidden to reach
Covering property and extractability, in addition, in actual operation, when dot percentage reaches 0.5, using half color after photoshop screening
In changing the line map (dot shape is circle), two neighboring site has contacted with each other the case where not generating displacement, can not carry out phase
Position 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, is reached
The hiding purpose of anti-counterfeiting 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, there has been no the movable distance progress to boundary node is relevant deep
Research, seldom some are also limited in the subjective judgement and theoretical basis of shallow-layer, and according to site displacement method, all sites are moved
Dynamic distance is D/2, and moving direction is the direction (i.e. along the cable direction of formation) of screen angle, is found in the present invention, when
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, at halftoning early period
Screening parameter can be set, therefore screen frequency is datum, screen frequency has determined the distance between two neighboring site in reason
The side length D of D and mesh tune unit2, D=D2, the distance between two site closest approaches D1Equal to two neighboring site it
Between distance D subtract the value of two radius r, in the case where screen frequency is certain, D1Then depend on site radius r, 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 be just in contact with the site in front of it but
It does not overlap；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,
The especially site of lap-joint or borderline site can make the profile of anti-counterfeiting information just be perceived by the human eye before extraction,
Antiforge function is caused to fail；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
Very big counter productive, the visual perception of lap-joint clearly, the especially site of lap-joint or borderline net
Point can make the profile of anti-counterfeiting information just be perceived by the human eye before extraction, antiforge function is caused to fail；To guarantee centainly hidden
Covering property, while guaranteeing that borderline site can contribute to extract identity again, when site moving distance S be it is maximum away from
From D1When, it extracts performance and reaches most preferably, specific as follows:
S=D1；
And because are as follows:
So
(2), in the prior art, the moving direction of phase modulation site be only along screen angle direction front and back or
Perpendicular to 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 are as follows: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 are as follows:
4, step four of the invention designs different gratings and knows in conjunction with step 3 for different phase-modulation angles
Other angle, β are 90 ° or 0 °, 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
Between 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
The angular dimension of Ω is classified in the influence of grating, allows in identification there is corresponding grating to 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, cross-shaped structure on host image half-tone picture
One side and horizontal line between angle be β, step 4 further include the identification grating of digital document form is prepared into it is corresponding
Grating in kind, 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 mother matrix screen angle and identification grating angle when being 0 ° in the embodiment of the present invention 1, site displacement is adjustable
The schematic diagram of range processed；
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
A kind of identification grating angle based on phase modulation determines method, includes 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, the condition that host image need to meet are as follows:
(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, in mother matrix
The position of upper determining hidden area remembers that color value of all pixels point of hidden area on mother matrix is identical, is denoted as α, the model of α
Enclose 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；It is logical to 4
Road is respectively set screening parameter and carries out screening processing, and screening processing adjusts screen using half, screening parameter include output resolution ratio,
Screen frequency, dot shape and screen angle when carrying out screening processing respectively to 4 channels, are differentiated using identical output
Rate, screen frequency and dot shape, dot shape are circle, and screen frequency is 96lpi in this implementation, and output resolution ratio is
2400dpi, the screen angle θ of mother matrix are 0 °, any combination that the screen angle of 3 secondary versions is 15 °, 45 ° and 75 °；This implementation
θ is 0 ° of difficulty that can reduce hiding anti-counterfeiting information in example；
Wherein, the method that each channel carries out screening processing are as follows: choose channel, 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；?
To 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, 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, the method for establishing site constituency are as follows:
(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 "；It will " 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
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,
The site that site constituency is chosen out in " figure layer 2 " is the site for needing to carry out phase-modulation, is denoted as set A；
The method of Such phase modulation are as follows: the mobile identical angle and distance in all sites of set A is remembered 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 center of site a
Point 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 site a
Mobile distance, γ are the angle between the line and horizontal line of the central point in the central point after site is mobile and home position,
Q ' is any point on polar equation ρ, and the moveable position of q ' is the dashed trace formd in Fig. 2, after remembering screening,
The distance between two neighboring site be D (in known in this field,), dashed trace is circle, and its radius is equal to
D/2, therefore, the polar equation of dashed trace are as follows:Site a is moved to any point in dashed trace,
The hiding and identification of anti-counterfeiting information may be implemented；
After the completion of phase-modulation, referring to fig. 4, the mother matrix half-tone picture for carrying anti-counterfeiting information is obtained, by itself and 3 width pair versions
Half-tone picture carries out image synthesis, new image two in photoshop, the length and width of image two and the length and width phase of host image
Together, the input resolution ratio of image two is identical with the output resolution ratio, and background content is white, and color mode is CMKY mode,
The mother matrix half-tone picture and 3 width pair version half-tone pictures are copied into corresponding Color Channel, referring to Fig. 5, obtain carrying anti-
The host image half-tone picture of fake information completes hiding for anti-counterfeiting information；
Step 4: the identification of anti-counterfeiting information
Production identification grating: preparing the identification grating of 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 are as follows: to form Moire fringe, design T1=2r so that during the extraction process, present a contrast and
So that anti-counterfeiting information shows, r represents the radius of site, and becauseTherefore T1=2r is equivalent to:To further,Identification grating blackstreak and clear bar has been determined with this
The width of line；
Identification 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 collection
The site and identification grating for closing A are formed, and there is the anti-counterfeiting information of powerful contrast to be mentioned to complete the identification of anti-counterfeiting information
Take the stacking chart of the identification grating and host image half-tone picture of anti-counterfeiting information, the determination method of angle β are as follows:
(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,
Site 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 shown in h1, h2 and h3
When a position, in the identification anti-counterfeiting information stage, at this 4 positions, it is mobile after site and angle be 0 ° of identification grating just
It is 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
Angle between the line and screen angle direction of Ω 2, the center of circle h3 and q is Ω 3；Again because aforementioned, γ is after site is mobile
Angle between the center of circle and the circular line and horizontal line in home position, in the present embodiment, screen angle is 0 °, therefore, right
It answers, as Ω≤γ≤Ω1Or Ω2≤γ≤Ω3When, use angle β to be identified for 0 °, remaining section is then using folder
Angle beta is 90 ° and is identified；
(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 brush output, 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, then controls exposure output by output equipment and phenanthrene is made at printing plate, or correspondence
Forest tract shines seal carving version 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,
Complete identification.
Furtherly,
In the present embodiment step 4, the production method that identifies grating are as follows:
(1), photoshop software to be opened, figure layer X is created, background colour is set as transparent (no background colour), then built
The first rectangle of a length and width particular value is drawn in figure layer with the rectangle tool, then Fill Color is (preferably in the rectangle frame finished
For 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
And cover on the first rectangle, the first rectangle is located at the bottom in the second rectangle, then selects " editor/definition pattern ", will carry out
Pattern save as " pattern 0 "；Wherein, the length of the first rectangle is T1, the length of the second rectangle is T1+T2, as net
The side length of mesh tune 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 directly
The size of line grating, resolution ratio is identical with the output resolution ratio, is then filled out using " pattern 0 " saved come Photoshop Z
The identification grating for detecting anti-counterfeiting information is formed after filling.
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 (weighting noise
Than) the host image half-tone picture for being not embedded into anti-counterfeiting information and the host image half-tone picture for carrying anti-counterfeiting information are evaluated respectively
Similarity between the two, so that the concealed evaluation result of hiding information is obtained indirectly, it is 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,
Image is 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；maxf△(x, y) and minf△(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 not
Together；(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 (weighting noise
Than) the host image half-tone picture for being not embedded into anti-counterfeiting information and the host image half-tone picture for carrying anti-counterfeiting information are evaluated respectively
Similarity between the two, so that the concealed evaluation result of hiding information is obtained indirectly, it is 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 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 (weighting noise
Than) the host image half-tone picture for being not embedded into anti-counterfeiting information and the host image half-tone picture for carrying anti-counterfeiting information are evaluated respectively
Similarity between the two, so that the concealed evaluation result of hiding information is obtained indirectly, it is 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 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 (weighting noise
Than) the host image half-tone picture for being not embedded into anti-counterfeiting information and the host image half-tone picture for carrying anti-counterfeiting information are evaluated respectively
Similarity between the two, so that the concealed evaluation result of hiding information is obtained indirectly, it is 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 in the present invention angle β determination method are as follows:
(1), referring to fig. 20, in the hiding anti-counterfeiting information stage, the center of circle q displaced position of site a is q ', h4, h5 in Fig. 3
In the case where 4 positions shown in h6, it can cause in the identification anti-counterfeiting information stage, on this 4 positions, after mobile
Site is that 0 ° of identification grating is just tangent with angle, if the mobile position in site continues to lean in the hiding anti-counterfeiting information stage
When nearly identification grating is mobile, since the identification grating that can be 0 ° with angle generates lap, so use at this time angle for
It is higher to extract resolution for it after 90 ° of identification 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 be Ω, the angle between the line and screen angle direction of the center of circle h4 and q is Ω4, the line of the center of circle h5 and q with plus
Angle between net angle direction is Ω5, the angle between the line and screen angle direction of the center of circle h6 and q is Ω6；γ is net
Angle between the line and horizontal line of the center of circle q of center of circle q ' and home position after point is mobile, 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
Angle β is then used to be identified for 90 °；
(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:
WhenWhen, β=θ；
WhenWhen ,+90 ° of β=θ.
Claims (10)
1. a kind of identification grating angle based on phase modulation determines method, which comprises the steps of:
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 are as follows: 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；
The method for building up in site constituency are as follows:
(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；
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: preparing the identification grating of 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
Identification anti-counterfeiting information: 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, the determination method of angle β are as follows:
WhenWhen, β=θ；
WhenWhen ,+90 ° of β=θ.
2. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: note institute
Stating screen frequency is l, polar equation ρ are as follows:
3. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
In step 2, host image halftone process is completed in photoshop software, and host image is opened in photoshop, institute
It states screening processing and screen is adjusted using half in photoshop；
The method that each channel carries out screening processing are as follows: choose channel, 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.
4. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
The screen angle θ of mother matrix is 0 °, any combination that the screen angle of 3 secondary versions is 15 °, 45 ° and 75 °.
5. the identification grating angle according to claim 4 based on phase modulation determines method, it is characterised in that: described
In step 4, the determination method of angle β are as follows:
WhenWhen, β=θ；
WhenWhen ,+90 ° of β=θ.
6. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
It further include 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, in place in step 3
Setting identification label on master image half-tone picture, identification are labeled as cross-shaped structure, one side and horizontal line of cross-shaped structure it
Between angle be β, exposure output is then controlled into printing plate by output equipment, or it is corresponding film be made shine seal carving version again,
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, 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.
7. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
In step 3, image synthetic method are as follows:
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.
8. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
Output resolution ratio is the integral multiple of screen frequency.
9. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: described
Output resolution ratio is 2400dpi, screen frequency 96lpi.
10. the identification grating angle according to claim 1 based on phase modulation determines method, it is characterised in that: institute
Stating output resolution ratio is 1920dpi, screen frequency 96lpi.
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| CN108790468A (en) * | 2018-06-06 | 2018-11-13 | 合肥康之恒机械科技有限公司 | A kind of host image processing method of optimization anti-counterfeiting information concealment and extractability |
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Application publication date: 20190108 |