CN108830775A - A kind of concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information - Google Patents
A kind of concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information Download PDFInfo
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- CN108830775A CN108830775A CN201810586851.7A CN201810586851A CN108830775A CN 108830775 A CN108830775 A CN 108830775A CN 201810586851 A CN201810586851 A CN 201810586851A CN 108830775 A CN108830775 A CN 108830775A
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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
Abstract
The invention discloses a kind of host image processing methods for optimizing anti-counterfeiting information concealment and extractability, include the following steps：Step 1: the selection of host image；Step 2: host image halftone process：Screening parameter is respectively set to 4 Color Channels and carries out screening processing, 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：After the completion of phase-modulation, the mother matrix half-tone picture for carrying anti-counterfeiting information is obtained, it is subjected to image with 3 width pair version half-tone pictures and is synthesized, obtains the host image half-tone picture for carrying anti-counterfeiting information, completes hiding for anti-counterfeiting information.The present invention expands the modulated angular range in site, optimizes the modulated distance in site, improves the concealment and extraction effect of anti-counterfeiting information.
Description
Technical field
The invention belongs to grating field of anti-counterfeit technology, and in particular to a kind of anti-fake figure of the concealed grating of improvement anti-counterfeiting information
As setting 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 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
For screen angle direction, in existing some progress, also have using the way perpendicular to the mobile D/2 in screen angle direction,
Since screen frequency l certainly will be arranged in image halftoning process, D is a known numeric value,
Although phase modulation, using very universal, there is also following deficiencies：
1, there are far-reaching technology prejudice for optimal site principle：Existing research thinks that the displacement setting of site must expire
When the site of the optimal site principle of foot, only composition anti-counterfeiting information is located at optimal dot location, digital raster detection is anti-fake
When information, the reproduction of anti-counterfeiting information is just most obvious, clear, but it is inclined to always exist the used technology having for many years in the prior art
See, it is believed that optimum point only moves D/2 along the vertical direction in screen angle direction or screen angle, causes to refer to from theory
The modulated angle and distance in site is very limited in the angle led；
2, overlapped Study on Problems is generated without in place to site：In order to realize Moire effect, it is contemplated that site constituency
All sites carry out identical displacement, and direction of displacement is the direction vertical along screen angle direction or screen angle, displacement
Distance is D/2, i.e., in existing method, lumps together the site of all colours value (dot percentage), without specific aim；
Simultaneously as screening parameter can be arranged in early period halftone process, therefore screen frequency is datum, screen frequency has determined D
With the side length D of single mesh tune unit2, D=D2, therefore, D/2 is definite value；But it is located at the part site on the selection border of site,
Its practical movably distance is the distance between two site closest approaches, is denoted as D1, with the increase of dot percentage, D1Meeting
It is gradually reduced, therefore, D1For variable；Work as D1When less than D/2, if the method still according to the prior art carries out phase-modulation,
The overlap joint on boundary between site can then be caused, cause strong visual perception, so that anti-fake failure, in the prior art not yet
Actual range is to concealment and the synergy for extracting performance generation between considering site.
Summary of the invention
The object of the present invention is to provide a kind of concealed grating anti-counterfeiting image setting methods of improvement anti-counterfeiting information, expand
The modulated angular range in site optimizes the modulated distance in site, improves the concealment of anti-counterfeiting information and extracts effect
Fruit.
The present invention provides the following technical solutions：A kind of improvement anti-counterfeiting information concealed grating anti-counterfeiting image setting side
Method includes the following steps：
Step 1: the selection of host image
Host image is selected, decomposing host image makes it by C-channel, the channel M, the channel Y and K channel totally 4 Color Channels
Composition；
There is the hidden area that anti-counterfeiting information can be set at least one Color Channel of host image, remember hidden area
The Color Channel at place is mother matrix, and color value of all pixels point of hidden area on mother matrix is α, and α is 0.1~0.5；It is surplus
Remaining Color Channel is 3 secondary versions；When the hidden area that α is 0.1~0.5 can not be selected, then host image is reselected；
Step 2: host image screening is handled
Screening parameter is respectively set to 4 Color Channels and carries out screening processing, obtains the mother matrix halftoning being made of site
Figure and 3 width pair version half-tone pictures；
Step 3: anti-counterfeiting information is hidden
It chooses and needs hiding anti-counterfeiting information, corresponding site constituency is established in the hidden area of mother matrix half-tone picture,
Remember that the site in the constituency of site is set A, carries out phase-modulation；
The method of phase-modulation is：Remember any site e in set A, pole is established as pole using the central point q of site e
Coordinate, the position of the mobile rear center's point of site e are q ', and the polar coordinates of q ' are (ρ, γ), and it is radius that q ', which is by the center of circle, ρ of pole,
And any point in the circular trace with 4 notches, by the mobile angle identical with site e in remaining site of set A and away from
From；
The screening parameter includes screen angle and screen frequency, remembers that the screen angle of mother matrix is θ, remembers the screen frequency
For l, the α value obtained according to step 1 is described to work asWhen, the radius of the circular trace with 4 notches isEquation of locus is：
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, completes hiding for anti-counterfeiting information.
It is as above-mentioned technical proposal to further describe：
WhenWhen, the radius of the circular trace with 4 notches isEquation of locus is：
It is as above-mentioned technical proposal to further describe：
In the step 2, screening processing adjusts screen using half in photoshop software, and screening parameter further includes output
Resolution ratio and dot shape, when carrying out screening processing respectively to 4 Color Channels, using identical output resolution ratio, screening line
Several and dot shape, any combination that the screen angle of 4 Color Channels is 0 °, 15 °, 45 ° and 75 °.
It is as above-mentioned technical proposal to further describe：
The screen angle of the mother matrix is that θ is 0 °, and the dot shape is circle.
It is as above-mentioned technical proposal to further describe：
In the step 2, screening processing adjusts screen using half in photoshop software, and screening parameter further includes output
Resolution ratio and dot shape, when carrying out screening processing respectively to 4 Color Channels, using identical output resolution ratio, screening line
Several and dot shape, any combination that the screen angle of 4 Color Channels is 0 °, 18.44 °, 45 ° and 71.57 °, output are differentiated
Rate is 2400dpi, screen frequency 96lpi.
It is as above-mentioned technical proposal to further describe：
In the step 3,
WhenWhen, the radius of the circular trace with 4 notches isEquation of locus is：
WhenWhen, the radius of the circular trace with 4 notches isTrack side
Cheng Wei：
It is as above-mentioned technical proposal to further describe：
Described further includes step 4：The identification of anti-counterfeiting information：
(1), production identification grating：The identification grating for preparing digital document form identifies that the area of grating is greater than hidden area
The area in domain, identification grating is parallel to each other to be alternatively arranged by the identical blackstreak of length and transparent stripe to be formed, blackstreak
Width be T1, the width of transparent stripe is T2, wherein
(2), it will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation identification grating makes
It must identify that it is β that angle is formed between grating and horizontal line, is then moved forward and backward identification grating along the direction β, until the net of set A
Point forms the anti-counterfeiting information with powerful contrast with identification grating, to complete the identification of anti-counterfeiting information.
It is as above-mentioned technical proposal to further describe：
The determination method of the β is：
It is as above-mentioned technical proposal to further describe：
It further include that will be embedded with carrying after obtaining the host image half-tone picture of carrying anti-counterfeiting information in the step 3
The host image half-tone picture the output for printing of anti-counterfeiting information, before the output for printing, the setting identification mark on host image half-tone picture
Note, identification are labeled as cross-shaped structure, and the angle between one side and horizontal line of cross-shaped structure is the β, then by defeated
Equipment control exposure output is at printing plate out, or it is corresponding film be made shine seal carving version again, obtain the host for carrying anti-counterfeiting information
Image is in kind；
It further include being prepared into the identification grating of digital document form after production identification grating in the step step 4
Corresponding material object grating, grating in kind is covered on host image material object, is marked according to identification and is rotated grating in kind, so that
The blackstreak or transparent stripe and horizontal angle of grating in kind are the β, are then moved forward and backward along the direction β in kind
Grating completes identification until observing anti-counterfeiting information.
It is as above-mentioned technical proposal to further describe：
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, 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.
Beneficial effects of the present invention：The modulated angular range in site is expanded, the modulated distance in site is optimized, mentions
The high concealment and extraction effect of anti-counterfeiting information, it is specific as follows：
1, the threshold value that generates that overlapped for site is determined：It is found in the present invention, works as D/2=D1When, at this point, being located at site constituency
Borderline part site is just in contact with the site in front of it but does not overlap, D after mobile1Equal 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 the corresponding color value α (i.e. dot percentage) of pixel on channel, obtains following formula：Therefore, as D/2 etc.
In D1When,Site after moving at this time is just in contact with the site in front of it but does not overlap；In the prior art, still
There is not research to influence in view of this threshold value on site displacement method bring；
2, the distance that site is mobile in phase-modulation is optimized：Based on aforementioned, only it is less than or equal in α in the present inventionGinseng
Existing site displacement method is examined, i.e. the mobile distance in site is D/2, asWhen α is greater thanTo guarantee centainly
Concealment, while guaranteeing that borderline site can contribute to extract identity again, site moving distance S is two nets
The distance between point closest approach D1, as
3, the direction that site is mobile in phase-modulation is optimized
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 the phase at 4, after present invention optimization
Position modulator approach, the moveable position composition in site have the circular trace of notch at 4, and the polar equation of the track is：
WhenWhen, each site in the constituency of site, its own modulated position composition with lacking everywhere
The circular trace of mouth, the radius of the circular trace areEquation of locus is：And
WhenWhen, each site in the constituency of site, its own modulated position composition with lacking everywhere
The circular trace of mouth, the radius of the circular trace areEquation of locus is：And
And
Therefore, phase-modulation is carried out using method of the invention, has overturned the technology prejudice of the prior art, determination is reaching
On the basis of identical concealment effect, the modulated range in site is expanded；
4, the identification angle of design identification grating
According to the equation of locus of previous designs, when extracting hiding anti-counterfeiting information using identification grating, accurate extract is remembered
Out when anti-counterfeiting information, identify that the angle (acute angle) between grating and horizontal line is β：
Different β is used according to the angle of site modulation, prevents the site in site constituency to be overlapped with identification grating generation, drops
The conspicuousness of low extraction；
5, the scope of application of the present invention is wider, more flexible：Step 1 and two can determine hidden area on Color Channel
Color value, in halftone process, color value α corresponds to the dot percentage of site, indirectly determines phase-modulation
The distance of site displacement, step 1 have determined the data such as color mode and the image size of host image, have further defined in the process
The specific location of mother matrix, hidden area, opens host image in photoshop, and observation colouring information finds corresponding hide
Region, it is easy to operate；Host image can be the original copy directly made in image processing software, be also possible to randomly select
Qualified original copy；
6, the present invention guarantees good information hiding and extractability in terms of the selection of host image：Only consider 0.1~
0.5 range, it is anti-fake when dot percentage is less than 0.1 because in actual operation, testing and finding by many experiments
The concealment of information is very good, but it is very poor to extract recognition performance；When dot percentage is greater than 0.5, the extraction of anti-counterfeiting information
Recognition performance is preferable, but concealment is weaker, to reach best concealment and extractability, in addition, in actual operation, net
When point percentage reaches 0.5, (dot shape is circle), two neighboring net in the half-tone picture after using photoshop screening
Point has contacted with each other the case where not generating displacement, can not carry out phase-modulation, the conspicuousness at edge is clearly；
7, the present invention has practical application value：Step 3 further includes that will be embedded with the host image half for carrying anti-counterfeiting information
Tone illustration the output for printing, before the output for printing, setting identification label, identification are labeled as cross on host image half-tone picture
Structure, the angle between one side and horizontal line of cross-shaped structure are β, and step 4 further includes by the identification of digital document form
Grating is prepared into corresponding grating in kind, and identification label plays indicative function, do not influence antiforge function, can aspect user
Verify 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)；
Fig. 2 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. 3 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. 4 is the host image in the embodiment of the present invention 2 (color information is not shown)；
Fig. 5 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)；
Fig. 6 is the host image half-tone picture in the embodiment of the present invention 2 after covering identification grating (color information is not shown)；
Fig. 7 is the host image in the embodiment of the present invention 3 (color information is not shown)；
Fig. 8 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)；
Fig. 9 is the host image half-tone picture in the embodiment of the present invention 3 after covering identification grating (color information is not shown)；
The schematic diagram that Figure 10 is any site e on a mother matrix in the present invention (site is set as hollow in order to facilitate observation of)；
Figure 11 is schematic diagram (the site setting in order to facilitate observation of of any site e moveable position on a mother matrix in the present invention
It is hollow)；
Figure 12 is the schematic diagram (net in order to facilitate observation of in the present invention on a mother matrix after any site e moveable position optimization
Point is set as hollow)；
Figure 13 is the rough schematic view of Figure 12 of the present invention；
The state tangent with identification grating is illustrated after any site e is mobile on one mother matrix when Figure 14 is β=θ in the present invention
Figure；
The state tangent with identification grating after any site e is mobile on one mother matrix when Figure 15 is+90 ° of β=θ in the present invention
Schematic diagram；
Figure 16 is the schematic diagram of the moveable position of part range in Figure 12 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 concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information, includes the following steps：
Step 1: selection and decomposition host image
Host image is randomly choosed, for hiding anti-counterfeiting information, the condition which need to meet is：
(1), the digital document being made of m*n pixel；
(2), image model is arranged to CMYK mode in photoshop software by the present embodiment 1, decomposes host's figure
Picture, making it by C-channel, the channel M, the channel Y and K channel, totally 4 Color Channels form；
There is the hidden area that anti-counterfeiting information can be set, hidden area tool at least one Color Channel of host image
There is s*s pixel, the Color Channel where remembering the hidden area is mother matrix, and all pixels point of hidden area is in mother
Color value in version is all the same, is denoted as α, and α is 0.1~0.5；Remaining Color Channel is 3 secondary versions；
When can not select α be 0.1~0.5 hidden area when, then return step one reselect host image again into
Row host image decomposes, until finding the hidden area that α is 0.1~0.5；
Referring to Fig. 1, in the present embodiment 1, by step 1, what is obtained meets the host image of condition, included input
Resolution ratio is 2400lpi, m=n=3780, s=1260, and the length and width of host image are 4cm, α in obtained hidden area
Value is 0.15；Mother matrix is C-channel, and the channel M, the channel Y and K channel are secondary version；
Step 2: host image halftone process
Screening parameter is respectively set to 4 Color Channels and carries out screening processing, specially：
Host image is opened in photoshop, chooses single Color Channel, Color Channel is converted into bitmap, is converted
When setting output resolution ratio be 2400dpi, then adjust screen to carry out screening using half in photoshop, screening parameter includes
Output resolution ratio, screen frequency, dot shape and screen angle, to 4 Color Channels be all made of identical output resolution ratio,
Screen frequency and dot shape carry out screening, and dot shape is circle, and screen frequency is 96 lpi, C-channel in the present embodiment 1
Screen angle be 0 °, the screen angle in the channel M, the channel Y and K channel is respectively 15 °, 45 ° and 75 °；
It is repeated 4 times aforementioned operation, 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
(1), site constituency is established
It chooses and needs hiding anti-counterfeiting information, in embodiment, anti-counterfeiting information is figure and literary combinatorics on words, in image procossing
Mother matrix half-tone picture is opened in software, site constituency is established in corresponding hidden area according to the profile of anti-counterfeiting information, is established
The method in site constituency is：
A, 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., long
Width is 4cm, and the input resolution ratio of image one is 2400dpi, and background content is white, obtains " 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；
B, " 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；
(2), phase-modulation
The site of set A is subjected to phase-modulation, method is：
A, remember any site e in set A, establish polar coordinates by pole of the central point q of site e, site e is mobile
Rear center's point is q ', and the polar coordinates of q ' are (ρ, γ), and ρ represents mobile distance, and γ represents mobile angle, and q ' is with pole
For the center of circle, ρ be radius and with 4 notches circular trace on any point, with reference to site e, by remaining site of set A
Mobile angle and distance identical with site e, in the present embodiment, directly in photoshop software, that chooses set A owns
Site is modulated simultaneously, easy to operate accurate；Screening parameter includes screen angle and screen frequency, remembers the screening angle of mother matrix
Degree is θ, remembers that the screen frequency is l；
B, the α value obtained according to step 1, the value of the α of the present embodiment are 0.15, are belonged toRange, θ is
0 °, equation of locus is：
Site e is moved to any point on aforementioned equation of locus, the q ' in the present embodiment 1, after preferably site e is mobile
Polar coordinates beMeanwhile remaining site of set A with the mobile same distance of jet nit point e and
Angle, after completing phase-modulation, at this point, anti-counterfeiting information is already embedded in host image；Obtain carrying the mother matrix of anti-counterfeiting information
It is carried out image with 3 width pair version half-tone pictures and synthesized by half-tone picture, new image two in photoshop, image two
Length and width are identical with the length and width of host image, and the input resolution ratio of image two is 2400dpi, and background content is white, color mode
For CMKY mode, mother matrix half-tone picture and 3 width pair version half-tone pictures are copied into corresponding Color Channel, referring to fig. 2, obtained
To the host image half-tone picture for carrying anti-counterfeiting information, hiding for anti-counterfeiting information is completed；
Step 4：The identification of anti-counterfeiting information
Knowing method for distinguishing is：
(1), production identification grating：In photoshop, the identification grating of digital document form is prepared, identifies grating
Area be greater than hidden area area, identification grating by the identical blackstreak of length and transparent stripe be parallel to each other interval row
Column composition, the width of blackstreak are T1, the width of transparent stripe is T2；
T1Determination method be：To form Moire fringe, T is designed1=2r, r are site radius, so that during the extraction process,
It presents a contrast and anti-counterfeiting information is shown, and becauseTherefore T1=2r is equivalent to：To
Further,The width of identification grating blackstreak and transparent stripe has been determined with this；
(2), it will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation identification grating makes
It must identify that grating is parallel with horizontal line, then move up and down identification grating, until the site of set A is formed with identification grating
Anti-counterfeiting information with powerful contrast, referring to Fig. 3, obtains the identification for extracting anti-counterfeiting information to complete the identification of anti-counterfeiting information
The stacking chart of grating and host image half-tone picture；In the present embodiment,
Furtherly, in step 3, further include will be embedded with carry anti-counterfeiting information host image half-tone picture printing it is defeated
Out, before the output for printing, setting identification label, identification are labeled as cross-shaped structure, cross knot on host image half-tone picture
Angle between one side and horizontal line of structure is the β, then controls exposure output into printing plate or right by output equipment
Film should be made and shine seal carving version again, the host image for obtaining carrying anti-counterfeiting information is in kind；
, further include that the identification grating of digital document form is prepared into corresponding grating in kind, by light in kind in 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 is parallel with horizontal line, then moves left and right grating in kind, until observing anti-counterfeiting information, completes identification.
Embodiment 2
Referring to fig. 4,5 and 6, on the basis of embodiment 1, embodiment 2 the difference is that：(1), host image is not
Together；(2), anti-counterfeiting information is text；(3), 0.1 α.
Embodiment 3
Referring to Fig. 7,8 and 9, 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), the polar coordinates of the q ' after 0.25 α, preferably site e are mobile are
Comparative example
In this comparative example, control group 1,2 and 3 is set, carries out compareing test with embodiment 1,2 and 3 respectively：
(1), control group 1：Compared with Example 1, the difference is that the polar coordinates for the q ' being only that after site e movement
ForThe prior art is used, moving direction is perpendicular to screen angle, and moving distance is two site distances
Half；It obtains after accurately extracting anti-counterfeiting information, identifies the stacking chart of grating and host image half-tone picture；
(2), control group 2：Compared with Example 2, the difference is that the polar coordinates for the q ' being only that after site e movement
ForThe prior art is used, moving direction is screen angle, and moving distance is the one of two site distances
Half；It obtains after accurately extracting anti-counterfeiting information, identifies the stacking chart of grating and host image half-tone picture；
(3), control group 3：Compared with Example 3, the difference is that the polar coordinates for the q ' being only that after site e movement
ForThe prior art is used, moving direction is screen angle, and moving distance is two nets
The half of point distance；It obtains after accurately extracting anti-counterfeiting information, identifies the stacking chart of grating and host image half-tone picture；
Further, in this comparative example, identity evaluation is also extracted：
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 evaluate control group 1, control group 2, control group 3,
Embodiment 1, embodiment 2, the identification grating of embodiment 3 and host image half-tone picture stacking chart (accurately extract anti-counterfeiting information
In the state of), obtained result is as shown in table 1 below：
Table 1 extracts identity evaluation result
Embodiment 1 is compared with control group 1, using identical host image and anti-counterfeiting information, the stacking chart finally obtained,
The anti-counterfeiting information that embodiment 1 can intuitively be observed very much is more significant, that is, forms stronger contrast and contrast, mention
Take performance more preferable, referring to the data of table 1, the F of embodiment 1iAnd TiValue closer to 1, and with the data of control group 1 have compared with
Big gap, the extraction performance for objectively having reacted embodiment 1 are more preferable；Similarly, embodiment 2 and embodiment 3 achieve well
Effect, particularly, the comparison of embodiment 3 and control group 3, the α of the group is 0.25, that is, use the hidden method of control group 3,
Strong site overlap joint can be generated, therefore control group 3 can be obtained not as good as embodiment 3 in concealment and extraction performance
Effect.
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 similarly uses embodiment 2 and 3 to obtain the concealed evaluation result of hiding information indirectly
Identical method, it is as shown in table 2 below to obtain result：
2 concealment of table evaluates 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 Examples 1 to 3 is all close to 1, and is all larger than 0.9, with the host image half for not doing any processing
Tone illustration is compared, and difference is very small, can preferably hide anti-counterfeiting information；WSNR is larger simultaneously, further demonstrates this hair
Bright method expands the scope of application of phase-modulation optimum point principle, also, still has the hidden effect of comparable anti-counterfeiting information
Fruit is good, is not easy to be detected by human eye.
In conclusion compared with prior art, being characterized in particular in place of difference of the invention：
(1), site can be generated overlapped threshold value by finding：It is found in the present invention, works as D/2=D1When, at this point, being located at site
Part site on selection border is just in contact with the site in front of it but does not overlap, D after mobile1Equal to two neighboring net
The distance between point D subtracts the value of 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 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；
(2), the distance that site is mobile in phase-modulation is optimized
Based on difference (1), only it is less than or equal in α in the present inventionWith reference to existing site displacement method, i.e. site is moved
Dynamic distance is D/2；
When α is greater thanTo guarantee certain concealment, while guaranteeing that borderline site can do to extract identity again
It contributes out, when site moving distance S is maximum distance D1When, it extracts performance and reaches most preferably, it is specific as follows：
S=D1；
And because：
So when α is greater thanThe mobile distance in site is
(3), the direction that site is mobile in phase-modulation is optimized
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 at 4, and the present invention is directed toHidden area each site, referring to site e any in Figure 10, moveable position is a circle
Track, using the central point q in home position as the center of circle of circular trace, using D/2 as the radius of circular trace, referring to Figure 11, set
Any site e in A establishes polar coordinates by pole of the central point q of site e, and the position of the mobile rear center's point of site e is
Q ', q ' polar coordinates be (ρ, γ), q ' is any point on polar equation ρ, and polar equation is：
Such move mode may insure that site phase-modulation still has good extraction performance and hidden in the case where as small as possible
Cover performance；Similarly, forHidden area each site, moveable position is also a circular rail
Mark, using the center of circle of original site as the center of circle of circular trace, with D1For the radius of circular trace, polar equation is：
(4), the mobile direction in site is advanced optimized in conjunction with extraction performance
In the prior art, the stage is extracted in the identification of anti-counterfeiting information, designs the identification grating with the corresponding period, is covered on
On host image, identification grating accurately extracts anti-counterfeiting information under special angle, in the hiding stage of anti-counterfeiting information early period
In, when the direction of site modulation is along screen angle direction, which is perpendicular to screen angle direction, site tune
When the direction of system is perpendicular to screen angle direction, which is along screen angle direction；
The present invention advanced optimizes the mobile direction in site, is less than or equal to αFor, referring to Figure 12, q in figure1’、
q2’、 q3’、q4’、q5’、q6’、q7’、q8' be circular trace 8 points, when the center of circle, q is moved to q1’、q4’、q6’、 q7' this 4
When position, the site after movement is just tangent with the identification grating along screen angle direction, and when the center of circle, q is moved to q2’、q3’、
q5’、q8' this 4 positions when, it is mobile after site just with it is tangent perpendicular to the identification grating along screen angle direction；Work as net
The mobile center of circle of point is in q1' and q2' between, q3' and q4' between, q5' and q6' between and q7' and q8' between when, identify grating
Can be Chong Die with site, it is unable to reach preferable recognition effect, therefore, the present invention excludes aforementioned 4 modulation angle；
So in conjunction with Figure 13, in the present invention, only with from q1' arrive q4’、q3' arrive q5’、q6' arrive q7' and q2' arrive q8'
There are four the circular trace of notch, the direction mobile as site and distances for tool；Solve q1’、q2’、q3’、q4’、 q5’、q6’、
q7’、q8' polar coordinates：
q1' polar coordinates：Referring to Figure 14, the center of circle q and q are remembered1' line and screen angle direction (i.e. cable direction) between
Angle be Ω1, remember center of circle q1' and the line and horizontal line of center of circle q between angle be γ1, it is therefore, corresponding,Again because of γ1=Ω1-θ；It obtainsq1' pole
Coordinate is
q2' polar coordinates：Referring to Figure 15, the center of circle q and q are remembered2' line and screen angle direction (i.e. cable direction) between
Angle be Ω2, remember center of circle q2' and the line and horizontal line of center of circle q between angle be γ2, remember any two on horizontal line
Point is O1And O2, remember θ1=90 ° of-θ,Again because of γ2=Ω2-θ1；It obtainsq2' polar coordinates beAs
Similarly, note counter clockwise direction, ∠ O1qq4'=γ4, ∠ O1qq3'=γ3, ∠ O1qq5'=γ5；Note is square clockwise
To ∠ O1qq6'=γ6, ∠ O1qq7'=γ7, ∠ O1qq8'=γ8；Q can be obtained4' polar coordinates be：I.e.q3' polar coordinates be：I.e.
q5' polar coordinates be：I.e. q6' polar coordinates be：
I.e.q7' polar coordinates be： I.e.
q8' polar coordinates be：I.e.
Therefore, the phase modulating method referring to Figure 12 and after combining Figure 16, the present invention to optimize, the moveable position in site
The circular trace with notch at 4 is formed, the polar equation of the track is：
WhenWhen, each site in the constituency of site, its own modulated position composition with lacking everywhere
The circular trace of mouth, the radius of the circular trace areAngular range is：
(γ1≤γ≤γ4；γ3≤γ≤γ5；-γ6≤γ≤-γ7；-γ8≤γ≤-γ2)；
Obtained equation of locus is：
It is equivalent to：
Similarly, whenWhen, each site in the constituency of site, its own modulated position composition has four
Locate the circular trace of notch, the radius of the circular trace isAngular range is： (γ1≤γ≤γ4；γ3
≤γ≤γ5；-γ6≤γ≤-γ7；-γ8≤γ≤-γ2)；
Obtained equation of locus is：
It is equivalent to：
(5), the identification angle of design identification grating
According to the equation of locus that aforementioned distinctive points (4) are designed, when extracting hiding anti-counterfeiting information using identification grating,
When note accurately extracts anti-counterfeiting information, identify that the angle (acute angle) between grating and horizontal line is β：
Claims (10)
1. a kind of concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information, which is characterized in that include the following steps：
Step 1: the selection of host image
Select host image, decompose host image make it by C-channel, the channel M, the channel Y and K channel totally 4 Color Channels form；
There is the hidden area that anti-counterfeiting information can be set, note hidden area place at least one Color Channel of host image
Color Channel be mother matrix, color value of all pixels point of hidden area on mother matrix be α, α be 0.1~0.5；Remaining color
Channel is 3 secondary versions；When the hidden area that α is 0.1~0.5 can not be selected, then host image is reselected；
Step 2: host image screening is handled
Screening parameter is respectively set to 4 Color Channels and carries out screening processing, obtains the mother matrix half-tone picture and 3 being made of site
Width pair version half-tone picture；
Step 3: anti-counterfeiting information is hidden
It chooses and needs hiding anti-counterfeiting information, corresponding site constituency is established in the hidden area of mother matrix half-tone picture, remember net
Site in point constituency is set A, carries out phase-modulation；
The method of phase-modulation is：Remember any site e in set A, polar coordinates established as pole using the central point q of site e,
The position of the mobile rear center's point of site e is q ', and the polar coordinates of q ' are (ρ, γ), and q ' is to be radius as the center of circle, ρ using pole and have
Any point in the circular trace of 4 notches, by the mobile angle and distance identical with site e in remaining site of set A；
The screening parameter includes screen angle and screen frequency, remembers that the screen angle of mother matrix is θ, remembers that the screen frequency is l, root
The α value obtained according to step 1, whenWhen, the radius of the circular trace with 4 notches isRail
Mark equation is：
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, completes hiding for anti-counterfeiting information.
2. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 1, it is characterised in that：
It is described to work asWhen, the radius of the circular trace with 4 notches isEquation of locus is：
3. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 1, it is characterised in that：
In the step 2, screening processing adjusts screen using half in photoshop software, screening parameter further include output resolution ratio and
Dot shape, when carrying out screening processing respectively to 4 Color Channels, using identical output resolution ratio, screen frequency and site
Shape, any combination that the screen angle of 4 Color Channels is 0 °, 15 °, 45 ° and 75 °.
4. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 3, it is characterised in that：
The screen angle of the mother matrix is that θ is 0 °, and the dot shape is circle.
5. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 4, it is characterised in that：
In the step 3,
WhenWhen, the radius of the circular trace with 4 notches isEquation of locus is：
WhenWhen, the radius of the circular trace with 4 notches isEquation of locus is：
6. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 1, it is characterised in that：
In the step 2, screening processing adjusts screen using half in photoshop software, screening parameter further include output resolution ratio and
Dot shape, when carrying out screening processing respectively to 4 Color Channels, using identical output resolution ratio, screen frequency and site
Shape, any combination that the screen angle of 4 Color Channels is 0 °, 18.44 °, 45 ° and 71.57 °, output resolution ratio are
2400dpi, screen frequency 96lpi.
7. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 1, it is characterised in that：
Described further includes the identification Step 4: anti-counterfeiting information：
(1), 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
(2), it will identify that grating is covered on the host image half-tone picture for carrying anti-counterfeiting information, rotation identification grating, so that knowing
The other angle that formed between grating and horizontal line is β, then identification grating is moved forward and backward along the direction β, until the site of set A and knowledge
Other grating forms the anti-counterfeiting information with powerful contrast, to complete the identification of anti-counterfeiting information.
8. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 7, it is characterised in that：
The determination method of the β is：
9. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 7, it is characterised in that：
It further include that will be embedded with carrying anti-counterfeiting information after obtaining the host image half-tone picture of carrying anti-counterfeiting information in the step 3
Host image half-tone picture the output for printing, before the output for printing, the setting identification label on host image half-tone picture, identification mark
It is denoted as cross-shaped structure, the angle between one side and horizontal line of cross-shaped structure is the β, is then controlled by output equipment
Exposure output at printing plate, 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 reality after production identification grating in the step 4
Grating in kind is covered on host image material object by object light grid, is marked according to identification and is rotated grating in kind, so that grating in kind
Blackstreak or transparent stripe and horizontal angle are the β, are then moved forward and backward grating in kind along the direction β, until seeing
Anti-counterfeiting information is measured, identification is completed.
10. the concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information according to claim 1, 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.
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| CN201810586851.7A CN108830775A (en) | 2018-06-06 | 2018-06-06 | A kind of concealed grating anti-counterfeiting image setting method of improvement anti-counterfeiting information |
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Application publication date: 20181116 |