CN104794674A - Watermark method and watermark device based on host digital hologram - Google Patents

Abstract

The invention relates to the field of multimedia digital signal processing, in particular to a watermark method and a watermark device based on a host digital hologram. By the watermark method, virtual three-dimensional object Fresnel holographic watermark signals which are encrypted via random phases are preprocessed and then are subjected to carrier modulation and interference coding on the basis of spectral characteristic analysis of the host digital hologram, the watermark signals do not pass through frequency spectrum center positions of zero-order images, original images and conjugate images of the digital hologram in a spatial frequency domain, and the watermark signals can be embedded in the original host digital hologram by a spatial domain superposing method. Because the watermark signals are encrypted by the random phases, the safety of the host digital hologram is improved. The hologram at a watermark embedding position is directly cut out through the spatial domain so as to recover the watermark signals, information of the original host hologram is not required, and blind extraction is implemented.

Description

A kind of water mark method based on host's digital hologram and device

Technical field

The present invention relates to multimedia digital signal process field, particularly relate to a kind of water mark method based on host's digital hologram and device.

Background technology

Digital watermarking is the digital media rights resist technology occurred in recent years.So-called digital watermark technology be exactly by certain algorithm some significant information insertion in content of multimedia, but do not affect the value of original content and use and can not be humanly perceptible or be noticed.Watermark information can be the sequence number of author, corporate logo and have the text etc. of Special Significance.It can identified author, the owner, publisher and user, and carry copyright protection information and authentication information, object is the digital product identifying bootlegging and usurp, the legitimate copy of protection digital product and propagation.

Digital holography adopts the photoelectric detectors such as ccd video camera as recording medium, use numerical method reconstructing hologram, organically blending of optics and Digital Implementation means, make digital holography obtain extensive concern and achieve a series of application achievements, its application relates to the fields such as topography measurement, deformation measurement, Particle measurement, Digital holographic microscopy, false proof, three-dimensional imaging, medical diagnosis.In recent years, digital hologram theory and means is also increasingly extensive and obtain a series of achievement in research in the research of field of multi-media information safety, at optics, the digital hologram that the fields such as multi-media information security and the 3D imaging technique that develops rapidly at present have recorded Object light wave full detail becomes object information and preserves, transmission, a kind of important form of process, and the computing holography starting from the sixties in 20th century to develop rapidly carrys out synthetic hologram by computing machine, do not need the necessary being of object, can be easy to simulate various optical phenomena, further extend the range of application of holography.Digital hologram digital watermark is one of typical apply in the field of multi-media information safety of holography, in digital hologram water mark method, all kinds of optics such as Fourier hologram, Fresnel hologram, kinoform or computed hologram characteristic are often used as a kind of coded system of watermark signal, thus the optical hologram feature of watermark signal can be utilized to carry out boosting algorithm attack as the robustness under Strong shear attack at some.Along with further developing of the holographic applications such as 3D map, 3D navigation, 3D shopping; the hologram that have recorded object full detail is faced with important Copyright Protection equally, is that the discussion of the water mark method of digital hologram has positive effect to the expansion range of application of digital watermark technology and the fusion application of optics and digital means to bearer documents.But when hologram is host file, compared with general digital picture, hologram is the interferogram that have recorded all information of original Object light wave and formed after reference light wave modulation, be a texture maps recording interference fringe from the angle representations of spatial domain, from the angle of spatial frequency domain, zero-order image is included in general digital hologram, the diffraction light wave spectrum information of original image and conjugate image, therefore embed watermark signal should consider that the impact of watermark signal on host's hologram itself also should be taken into account that watermark signal is on the impact of host's hologram when optics or digital reproduction in the hologram, relevant solution is not yet had at present for the embedding three-dimensional body watermark on digital hologram basis.

Summary of the invention

Technical matters to be solved by this invention is: provide a kind of water mark method based on host's digital hologram and device, for promoting the security of host's digital hologram.

In order to solve the problems of the technologies described above, the technical solution used in the present invention is:

A kind of water mark method based on host's digital hologram is provided, comprises the following steps:

The cross-section data of encrypted virtual three-dimensional body and diffraction surfaces data;

Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting;

The frequency domain of the Fresnel diffraction distributed data after expansion encryption;

Fresnel diffraction distributed data after modulation expansion;

The zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding, and obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark.

Another technical scheme that the present invention adopts is:

Based on a watermarking device for host's digital hologram, comprising: watermark generation module and watermark embedding module;

Described watermark generation module comprises ciphering unit, the first computing unit, expanding element, modulating unit and removal unit;

Described ciphering unit, for cross-section data and the diffraction surfaces data of encrypted virtual three-dimensional body;

Described first computing unit, for calculating the Fresnel diffraction distribution of described virtual three-dimensional object, obtains the Fresnel diffraction distributed data after encrypting;

Described expanding element, for expanding the frequency domain of the Fresnel diffraction distributed data after encryption;

Described modulating unit, for modulating the Fresnel diffraction distributed data after expansion;

Described removal unit, interfere coding for the zero-order image removing the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Described watermark embedding module, for superposing described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtains host's digital hologram signal of embed watermark.

Beneficial effect of the present invention is: on the basis of host's digital hologram Analysis of Spectrum, to carrier modulation be carried out after the virtual three-dimensional object fresnel holography watermark signal pre-service be encrypted through random phase again and interfere coding, make watermark signal avoid the spectral centroid position of digital hologram zero-order image, original image and conjugate image in spatial frequency domain, then realize the embedding of watermark signal in original host's digital hologram in the method for spatial domain superposition.Owing to adopting random phase to be encrypted, and then improve the security of host's digital hologram.The hologram directly being intercepted watermark embedment place by spatial domain recovers watermark signal, without the need to the information of original host's hologram, achieves Blind extracting.Optical reproduction simulation test result shows, the method proposed has the good transparency, and when carrying out various attack to host's hologram, no matter be reproduction to host's hologram or the reproduction to three-dimensional body watermark all shows good robustness.

Accompanying drawing explanation

Fig. 1 is the flow chart of steps of the water mark method based on host's digital hologram of the specific embodiment of the invention;

Fig. 2 is specific embodiment of the invention virtual three-dimensional object Fresnel calculation holographic random phase encryption schematic diagram;

Fig. 3 is the schematic diagram of host's digital hologram of the specific embodiment of the invention;

Fig. 4 is the schematic diagram of the virtual three-dimensional object of the specific embodiment of the invention;

Fig. 5 is the schematic diagram of the spectral centroid position of the zero-order image of host's digital hologram of the specific embodiment of the invention, original image and conjugate image;

Fig. 6 is the schematic diagram of the host's digital hologram after the embed watermark of the specific embodiment of the invention;

Fig. 7 is the schematic diagram of the Fresnel calculation holographic watermark signal of the specific embodiment of the invention;

Fig. 8 is the schematic diagram of the Fresnel calculation holographic watermark signal of the mistake of the specific embodiment of the invention;

Fig. 9 is the schematic diagram of host's digital hologram digital reconstruction effect of the specific embodiment of the invention;

Figure 10 is host's digital hologram of the specific embodiment of the invention and the schematic diagram of three-dimensional body cross section digital reproduction effect;

Figure 11 is the three-dimensional watermark of the specific embodiment of the invention and the schematic diagram of host's hologram digital reconstruction effect;

Figure 12 is the schematic diagram of the digital reconstruction effect of three-dimensional body watermark and host's hologram after the filtering of the specific embodiment of the invention;

Figure 13 is the schematic diagram of the stained rear three-dimensional body watermark of the specific embodiment of the invention and the digital reconstruction effect of host's hologram;

Figure 14 is the structural representation of the watermarking device based on host's digital hologram of the specific embodiment of the invention.

Label declaration:

1, watermark generation module; 10, ciphering unit; 11, the first computing unit; 12, expanding element; 13, modulating unit; 14, removal unit; 2, watermark embedding module.

Embodiment

By describing technology contents of the present invention in detail, realized object and effect, accompanying drawing is coordinated to be explained below in conjunction with embodiment.

The design of most critical of the present invention is: be encrypted the cross-section data of virtual three-dimensional object and diffraction surfaces data, calculate the Fresnel diffraction distribution of described virtual three-dimensional object, the watermark generated is made to have higher security, use the watermark embedment host digital hologram of this generation, obtain that there is the high host's digital hologram of security, anti-counterfeiting mark field can be widely used in.

The explanation of technical terms that the present invention relates to:

Refer to Fig. 1, a kind of water mark method based on host's digital hologram, comprises the following steps:

The cross-section data of encrypted virtual three-dimensional body and diffraction surfaces data;

Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting;

The frequency domain of the Fresnel diffraction distributed data after expansion encryption;

Fresnel diffraction distributed data after modulation expansion;

The zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding, and obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark.

From foregoing description, beneficial effect of the present invention is: on the basis of host's digital hologram Analysis of Spectrum, to carrier modulation be carried out after the virtual three-dimensional object fresnel holography watermark signal pre-service be encrypted through random phase again and interfere coding, make watermark signal avoid the spectral centroid position of digital hologram zero-order image, original image and conjugate image in spatial frequency domain, then realize the embedding of watermark signal in original host's digital hologram in the method for spatial domain superposition.Owing to adopting random phase to be encrypted, and then improve the security of host's digital hologram.The hologram directly being intercepted watermark embedment place by spatial domain recovers watermark signal, without the need to the information of original host's hologram, achieves Blind extracting.Optical reproduction simulation test result shows, the method proposed has the good transparency, and when carrying out various attack to host's hologram, no matter be reproduction to host's hologram or the reproduction to three-dimensional body watermark all shows good robustness.

Further, after " superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark " step, also comprise:

Host's digital hologram signal of embed watermark obtains host's digital hologram drawing signal at watermark embedment place;

Calculate discrete Fourier transformation with the host's digital hologram drawing signal obtained, obtain digital spectrum;

Filter digital frequency spectrum, obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal;

Calculate the inverse discrete Fourier transform of described spectrum component, obtain the original of Fresnel calculation holographic watermark signal or conjugate image component;

Decipher the original or conjugate image component of described Fresnel calculation holographic watermark signal, obtain the diffraction light wave component of the Fresnel calculation holographic watermark signal of original image or conjugate image;

With the diffraction light wave component digital reconstruction virtual three-dimensional object watermark of the Fresnel calculation holographic watermark signal of described original image or conjugate image.

Further, described " filter digital frequency spectrum obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal " is specially: use window function to filter out the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal at digital spectrum.

Further, described " cross-section data of encrypted virtual three-dimensional body and diffraction surfaces data; Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting " be specially:

Adopt cross-section data and the diffraction surfaces data of random-phase marks encrypted virtual three-dimensional body;

Segmentation virtual three-dimensional object, obtains multiple cross section;

Random-phase marks is multiplied by each cross section;

Calculate the Fresnel diffraction in the single cross section after being multiplied by random-phase marks;

Discrete Fresnel transform is adopted to calculate the Object light wave COMPLEX AMPLITUDE in the single cross section after being multiplied by random-phase marks;

Calculate the Object light wave COMPLEX AMPLITUDE sum in multiple cross section, obtain the Fresnel diffraction distributed data after encrypting;

As shown in Figure 2, the Fresnel diffraction distributed data of the virtual three-dimensional object at plane of vision 1 place is multiplied by the discrete Fresnel diffraction at calculating observation plane 2 place after random-phase marks again, obtains the Fresnel diffraction distributed data after encrypting at plane of vision 2 place.

Wherein, the data in cross-section data and diffraction surfaces data refer to gray-scale value.

Further, described " frequency domain of the Fresnel diffraction distributed data after expansion encryption; the Fresnel diffraction distributed data after modulation expansion; the zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding; obtain real coding, described real coding is Fresnel calculation holographic watermark signal " is specially:

Calculate the discrete Fourier transformation of described Fresnel diffraction distributed data, obtain digital spectrum;

Null filling is used to expand described digital spectrum;

Calculate the inverse Fourier transform of the digital spectrum after expansion, obtain Fresnel diffraction distributed data;

Plane reference light carrier is used to modulate described Fresnel diffraction distributed data;

Remove the real-valued interference coding of zero-order image of the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal.

Further, described host's digital hologram is off-axis digital holography figure.

As shown in figure 14, present invention also offers a kind of watermarking device based on host's digital hologram, comprising: watermark generation module 1 and watermark embedding module 2;

Described watermark generation module 1 comprises ciphering unit 10, first computing unit 11, expanding element 12, modulating unit 13 and removal unit 14;

Described ciphering unit 10, for cross-section data and the diffraction surfaces data of encrypted virtual three-dimensional body;

Described first computing unit 11, for calculating the Fresnel diffraction distribution of described virtual three-dimensional object, obtains the Fresnel diffraction distributed data after encrypting;

Described expanding element 12, for expanding the frequency domain of the Fresnel diffraction distributed data after encryption;

Described modulating unit 13, for modulating the Fresnel diffraction distributed data after expansion;

Described removal unit 14, interfere coding for the zero-order image removing the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Described watermark embedding module 20, for superposing described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtains host's digital hologram signal of embed watermark.

From foregoing description, beneficial effect of the present invention is: on the basis of host's digital hologram Analysis of Spectrum, to carrier modulation be carried out after the virtual three-dimensional object fresnel holography watermark signal pre-service be encrypted through random phase again and interfere coding, make watermark signal avoid the spectral centroid position of digital hologram zero-order image, original image and conjugate image in spatial frequency domain, then realize the embedding of watermark signal in original host's digital hologram in the method for spatial domain superposition.Owing to adopting random phase to be encrypted, and then improve the security of host's digital hologram.The hologram directly being intercepted watermark embedment place by spatial domain recovers watermark signal, without the need to the information of original host's hologram, achieves Blind extracting.Optical reproduction simulation test result shows, the method proposed has the good transparency, and when carrying out various attack to host's hologram, no matter be reproduction to host's hologram or the reproduction to three-dimensional body watermark all shows good robustness.

Further, this device also comprises watermark reconstruction module;

Described watermark reconstruction module comprises acquiring unit, the second computing unit, filter element, the 3rd computing unit, decryption unit and reconstruction unit;

Described acquiring unit, for obtaining host's digital hologram drawing signal at watermark embedment place on host's digital hologram signal of embed watermark;

Described second computing unit, for calculating discrete Fourier transformation with the host's digital hologram drawing signal obtained, obtains digital spectrum;

Described filter element, for filter digital frequency spectrum, obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal;

Described 3rd computing unit, for calculating the inverse discrete Fourier transform of described spectrum component, obtains the original of Fresnel calculation holographic watermark signal or conjugate image component;

Described decryption unit, for deciphering the original or conjugate image component of described Fresnel calculation holographic watermark signal, obtains the diffraction light wave component of the Fresnel calculation holographic watermark signal of original image or conjugate image;

Described reconstruction unit, for the diffraction light wave component digital reconstruction virtual three-dimensional object watermark of the Fresnel calculation holographic watermark signal with described original image or conjugate image.

Embodiment 1

Off-axis digital holography figure is under object light and angle between reference meet certain condition, and diffraction light does not exist mutual interference, is a kind of hologram recording method the most often used.The light intensity of hologram page is object light U (x, y) and the result of reference light R (x, y) interference, can be formulated as:

h _c(x,y)＝[U(x,y)+R(x,y)]·[U(x,y)+R(x,y)] ^*

If Plane reference light wave R (x, y)=A _rexp [j2 π (α x+ β y)], to h _c(x, y) makes Fourier transform, represents Fourier transform symbol with F{}, and the frequency spectrum of off-axis digital holography figure can be expressed as:

F{h _c(x,y)}＝G ₀(f _x,f _y)+G ₊(f _x,f _y)+G _-(f _x,f _y)

Wherein g ₊(f _x, f _y)=F{R (x, y) U ^*(x, y) }, G _-(f _x, f _y)=F{R ^*(x, y) U (x, y) };

Wherein G ₀(f _x, f _y), G ₊(f _x, f _y), G _-(f _x, f _y) represent Zero-order diffractive optical spectrum, conjugate beam frequency spectrum and object light frequency spectrum respectively.With conjugate beam frequency spectrum G ₊(f _x, f _y) be example,

G ₊(f _x,f _y)＝F{R(x,y)U ^*(x,y)}

＝F{A _rexp(j2π(αx+βy))U ^*(x,y)}

＝A _rG' ₊(f _x-α,f _y-β)

Wherein G' ₊(f _x, f _y)=F{U ^*(x, y) }, above-mentioned formula shows, there is the conjugate image frequency spectrum G' centered by (α, β) at the frequency plane of off-axis digital holography figure ₊(f _x, f _y), in like manner, original image frequency spectrum G' _-(f _x, f _y) centered by (-α ,-β), and zero-order image frequency spectrum is positioned at frequency plane center, the segmentation feature of hologram means that arbitrary fragment also has similar spectrum structure, and just resolution declines.

In the present invention, first the watermark of random phase encrypted virtual three-dimensional body Fresnel calculation holographic is produced, then in conjunction with the spectral characteristic of host's digital hologram, carry out the pre-service of holographic watermark data and carrier modulation and removal zero-order image and interfere coding, make watermark signal avoid the spectral centroid position of zero-order image, original image and conjugate image in host's digital hologram in spatial frequency domain, being finally added to certain intensity by the real-valued watermark signal after coding completes the embedding of watermark signal in host's digital hologram.The recovery of watermark signal, without the need to the information of original host's digital hologram, achieves Blind extracting.Optical reproduction simulation test result shows, the method proposed has the good transparency, and when carrying out various attack to host's digital hologram, no matter be reproduction to host's digital hologram or the reproduction to three-dimensional body all shows good robustness.

A kind of water mark method based on host's digital hologram provided by the invention, comprises the following steps:

1, the cross-section data of encrypted virtual three-dimensional body;

2, the Fresnel diffraction distributed data at calculating observation plane 1 place;

3, after the Fresnel diffraction data at plane of vision 1 place are multiplied by random-phase marks again, described in calculating observation plane 2 place, the Fresnel diffraction of virtual three-dimensional object distributes, and obtains the Fresnel diffraction distributed data after encrypting;

The frequency domain of the Fresnel diffraction distributed data 4, after expansion encryption;

5, the Fresnel diffraction distributed data after modulation expansion;

6, the zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding, and obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

7, superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark.

Wherein, described " cross-section data of encrypted virtual three-dimensional body and diffraction surfaces data; Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting " be specially:

Adopt cross-section data and the diffraction surfaces data of random-phase marks encrypted virtual three-dimensional body;

Described random-phase marks encryption is specific as follows:

$\mathrm{\ψ}(m^{\′\′},n^{\′\′})={\mathrm{FST}}_D\left\{\right\{\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{\mathrm{FST}}_{d_i}\left[f_i(m,n)\exp \right[{\mathrm{jn}}_i(m,n)\left]\right]\left\}\exp \right[\mathrm{jb}(m^{\′},n^{\′})\left]\right\}$

Wherein f _i(m, n) is cross section Object light wave, n _i(m, n), b (m', n') represent the independent white noise sequence being distributed in [0,2 π] respectively, FST _drepresent that distance is the discrete Fresnel diffraction calculating of D.

Virtual three-dimensional object after segmentation encryption, obtains multiple cross section, namely adopts chromatography Fresnel diffraction Computing Principle; Calculate single cross section be multiplied by random-phase marks after Fresnel diffraction; Adopt discrete Fresnel transform calculate single cross section be multiplied by random-phase marks after Object light wave COMPLEX AMPLITUDE; Specific as follows:

According to three-dimensional body chromatography method Fresnel diffraction Computing Principle, can be expressed as with discrete Fresnel transform in the COMPLEX AMPLITUDE at plane of vision 1 place after random-phase marks is multiplied by single cross section:

$\begin{array}{c}{o}_i(m^{\′},n^{\′})=\frac{\exp \left({\mathrm{jkd}}_i\right)}{{\mathrm{j\λd}}_i}\exp \left[\frac{\mathrm{jk}}{{2d}_i}({\left(m^{\′}{\mathrm{\Δx}}_H\right)}^2+{\left(n^{\′}{\mathrm{\Δy}}_H\right)}^2)\right]\\ \×\underset{m=0}{\overset{M-1}{\mathrm{\Σ}}}\underset{n=0}{\overset{N-1}{\mathrm{\Σ}}}{f}_i(m,n)\exp \left[{\mathrm{jn}}_i(x,y)\right]\exp \left[\frac{\mathrm{jk}}{{2d}_i}({\left({\mathrm{m\Δx}}_0\right)}^2+{\left({\mathrm{n\Δy}}_0\right)}^2)\right]\exp [-j2\mathrm{\π}(\frac{{\mathrm{mm}}^{\′}}{M}+\frac{{\mathrm{nn}}^{\′}}{N})]\end{array}$

Wherein f _i(m, n) represents i-th cross section Object light wave COMPLEX AMPLITUDE, n _i(m, n) represents the independent white noise sequence being distributed in [0,2 π], d _ifor cross section is apart from the distance of plane of vision 1; λ is wavelength,

Calculate the Object light wave COMPLEX AMPLITUDE sum in multiple cross section, obtain the Fresnel diffraction distributed data of plane of vision 1 place virtual three-dimensional object.Specific as follows:

Virtual three-dimensional object can be expressed as in plane of vision Object light wave COMPLEX AMPLITUDE:

$O(m^{\′},n^{\′})=\underset{i=1}{\overset{L}{\mathrm{\Σ}}}{o}_i(m^{\′},n^{\′}),$ Wherein L represents cross section number;

Calculate discrete Fresnel transform with a fast fourier transform algorithm, obtain can being expressed as in the Object light wave COMPLEX AMPLITUDE at plane of vision 1 place after random phase is multiplied by single cross section:

$\begin{array}{c}{o}_i(m^{\′},n^{\′})=\frac{\exp \left({\mathrm{jkd}}_i\right)}{{\mathrm{j\λd}}_i}\exp \left\{\frac{\mathrm{jk}}{{2d}_i}\right[{\left(m^{\′}{\mathrm{\Δx}}_H\right)}^2+{\left(n^{\′}{\mathrm{\Δy}}_H\right)}^2\left]\right\}\\ \×\mathrm{FFT}\left\{f_i(m,n)\exp \right[{\mathrm{jn}}_i(x,y)\left]\exp \right\{\frac{\mathrm{jk}}{{2d}_i}[{\left({\mathrm{m\Δx}}_0\right)}^2+{\left({\mathrm{n\Δy}}_0\right)}^2]\left\}\right\}\\ (m^{\′},m=0~M-1,n^{\′},n=0~N-1)\end{array}$

Wherein represent object plane sample interval, M, N are number of samples, and m, n represent sampling spot sequence number, Δ x _h, Δ y _hfor sample interval, spatial domain corresponding after discrete Fourier transformation, m', n' are sampling spot sequence number, according to Shannon sampling thheorem,

Calculate the discrete Fresnel diffraction of distance for plane of vision 2 place of D again after the virtual three-dimensional object diffraction light wave datum at plane of vision 1 place being multiplied by random phase b (m', n'), obtain the Fresnel diffraction distributed data after encrypting.Wherein b (m', n') represents the independent white noise sequence being distributed in [0,2 π].

Described " frequency domain of the Fresnel diffraction distributed data after expansion encryption; the Fresnel diffraction distributed data after modulation expansion; the zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding; obtain real coding, described real coding is Fresnel calculation holographic watermark signal " is specially:

Calculate the discrete Fourier transformation of described Fresnel diffraction distributed data, obtain digital spectrum;

Null filling is used to expand described digital spectrum;

Calculate the inverse Fourier transform of the digital spectrum after expansion, obtain Fresnel diffraction distributed data;

Specific as follows:

Three-dimensional body discrete object lightwave data ψ (m ", n ") calculate identical discrete digital frequency spectrum of counting;

With the spectrum domain of null filling expansion, and make inverse fast Fourier transform, obtain pretreated Object light wave signal ψ ' (m ", n ").If spectrum domain makes L ₁doubly expansion, the Fresnel diffraction distributed data obtained can be expressed as:

${\mathrm{\ψ}}^{\′}(m^{\′\′},n^{\′\′})=\mathrm{ifft}{\left[\begin{array}{cc}\mathrm{fft}{\left(\mathrm{\ψ}(m^{\′\′},n^{\′\′})\right)}_{M*N}& 0\\ 0& 0\end{array}\right]}_{L_1\·M\×L_1\·N}$

If Plane reference light is Rexp [j2 π (α ₁x+ β ₁y)], by arranging carrier parameter α ₁, β ₁control three-dimensional body frequency spectrum pixel shift value l ₁, l ₂, make the digital spectrum of watermark signal avoid the center of zero-order image, original image and conjugate image in host's hologram, thus improve watermark signal digital reproduction as precision; Shift value l ₁and l ₂and meet relational expression between carrier parameter: l ₁=rem (α ₁l ₁m,L ₁m), l ₂=rem (β ₁l ₁n,L ₁n), wherein rem () represents complementation.

Plane reference light carrier is used to modulate described Fresnel diffraction distributed data;

Remove the real-valued interference coding of zero-order image of the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal.

Specific as follows:

Carrier modulation and the real-valued interference coding of removal zero-order image can be expressed as:

h(m”,n”)＝ψ'(m”,n”)R ^*(m”,n”)+ψ' ^*(m”,n”)R(m”,n”)

(m”＝0,1,…L ₁·M-1,n”＝0,1,…L ₁·N-1)

ψ ' in formula (m ", n ") represents the preprocessed signal of the three-dimensional body diffraction light wave through random phase encryption, ψ ' ^*(m ", n ") represents the conjugated signal of ψ ' (m ", n ").

Superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark.

The watermark embedment of described host's digital hologram signal is specially:

Additive process can be expressed as: h _w(x, y)=h _c(x, y)+α h (x, y)

Wherein h _c(x, y) and h (x, y) represent the holographic watermark signal of the virtual three-dimensional object after host's hologram and real coding respectively, h _w(x, y) represents containing watermark host digital hologram signal.

After " superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark " step, also comprise:

Host's digital hologram signal of embed watermark obtains host's digital hologram drawing signal at watermark embedment place;

Calculate discrete Fourier transformation with the host's digital hologram drawing signal obtained, obtain digital spectrum;

Filter digital frequency spectrum, obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal;

Calculate the inverse discrete Fourier transform of described spectrum component, obtain the original of Fresnel calculation holographic watermark signal or conjugate image component;

Decipher the original or conjugate image component of described Fresnel calculation holographic watermark signal, obtain the diffraction light wave component of the Fresnel calculation holographic watermark signal of original image or conjugate image;

With the diffraction light wave component digital reconstruction virtual three-dimensional object watermark of the Fresnel calculation holographic watermark signal of described original image or conjugate image.

Wherein, described " filter digital frequency spectrum obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal " is specially: use window function to filter out the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal at digital spectrum.

Specific as follows:

The host's digital hologram drawing intercepting watermark embedment place calculates discrete Fourier transformation;

Original or the conjugate image spectrum component of virtual three-dimensional object Fresnel calculation holographic watermark signal is leached at frequency domain window function;

Inverse discrete Fourier transform is calculated to the original or conjugate image spectrum component of above-mentioned virtual three-dimensional object Fresnel calculation holographic watermark signal, obtains the original or conjugate image component of virtual three-dimensional object through random phase encryption;

To the original or conjugate image component of the virtual three-dimensional object of above-mentioned acquisition, obtain virtual three-dimensional object diffraction light wave component by random phase decrypting process;

With the virtual three-dimensional object diffraction light wave component digital reconstruction virtual three-dimensional object of above-mentioned acquisition;

Digital reconstruction process can be expressed as;

$\begin{array}{c}{\mathrm{FST}}_{-d_i}\left\{{\mathrm{FST}}_{-D}\right\{F^{-1}\left[\right[H_c(u,v)+\mathrm{\αH}(u,v)\left]W(u,v)\right]\exp (-b(x^{\′},y^{\′}))\left\}\right\}\exp [-{\mathrm{jn}}_i(x_0,y_0)]\\ ={\mathrm{\αf}}_i(x_0,y_0)+n(x_0,y_0)\end{array}$

Wherein H _c(u, v) represents h _cthe Fourier transform of (x, y), W (u, v) represents spectral window, is superimposed upon the noise n (x of the watermark signal extracted ₀, y ₀) can be considered additive white Gaussian noise.

Three-dimensional body original image Object light wave data O (m', n') after deciphering is used to recover the discrete Fresnel inverse transformation of each cross section information can be expressed as:

$\begin{array}{c}{\mathrm{FST}}_{-d_i}\left[O(m^{\′},n^{\′})\right]\\ =\mathrm{IFFT}\{O(m^{\′},n^{\′})\×\frac{\exp (-\mathrm{jk}{d}_i)}{-\mathrm{j\λ}{d}_i}\exp \{\frac{-\mathrm{jk}}{2d_i}[{\left(m^{\′}\mathrm{\Δx}\right)}^2+{\left(n^{\′}\mathrm{\Δy}\right)}^2]\left\}\right\}\\ \×\exp \left\{\frac{-\mathrm{jk}}{{2d}_i}\right[{\left(\mathrm{m\Δ}{x}_0\right)}^2+{\left(\mathrm{n\Δ}{y}_0\right)}^2\left]\right\}\end{array}$

In the method for the invention, described virtual three-dimensional object, with reference to Fig. 4 (a) ~ 4 (c), as original watermark signal, calculate by random phase encryption Fresnel diffraction principle, the i.e. formula of above-mentioned ψ (m ", n "), obtains the distribution of random phase encrypted virtual three-dimensional body Fresnel diffraction; Then carry out carrier modulation after carrying out pre-service to diffraction light wave datum again and remove zero-order image interfering coding, watermark signal is made to avoid the spectral centroid position of host's digital hologram zero-order image, original image and conjugate image in spatial frequency domain, as shown in Fig. 5 (a), 5 (b), then realized the embedding of watermark signal in host's digital hologram by the method that spatial domain superposes;

Fig. 3 (a) is original host's digital hologram (1024*1024 pixel size), embeds the calculation holographic watermark signal (256*256 pixel size) (Fig. 5 (a)) of some strength in Fig. 3 spatial domain.

Fig. 6 (a) is the host's digital hologram after embed watermark, when watermark signal embedment strength is α=0.2, calculate the Y-PSNR PSNR=39.1655 between host's hologram (Fig. 3 (a)) and watermark hologram (Fig. 6 (a)), normalization mean square deviation NMSE=0.00012, human eye fails obviously to feel difference between the two, has the good transparency.

Fig. 7 is from the calculation holographic watermark signal recovered by watermark recovery step containing watermark host digital hologram (Fig. 6 (a)) when correct phase mask and calculating parameter; In Fig. 7, when diffraction distance is di, only have the information of cross section i clearly to reproduce, other cross section can only show fuzzy diffraction image in this distance, is consistent with 3-D display feature.

As shown in Figure 8, now each cross section information of three-dimensional body cannot clearly reproduce the cross section information that the phase mask of mistake and calculating parameter recover;

From containing watermark host digital hologram (Fig. 6 (a)) digital reconstruction host's thing optical field amplitude and hosting object image, as shown in Fig. 6 (b) He Fig. 6 (c), due to the carrier modulation treatment of watermark signal, the impact of watermark signal on host's hologram digital reproduction is mainly manifested in original image and conjugate image with the random disturbance of exterior domain, and less on the impact of hosting object image reproducing;

Process is suppressed when host's digital hologram has carried out zero-order image before digital reconstruction, three-dimensional watermark and host's hologram reconstructing effect are as shown in Fig. 9 (a) ~ Fig. 9 (c), no matter all reach the original objects image in host's hologram or three-dimensional body watermark signal and suppress process digital reproduction effect more clearly than without zero-order image, illustrate that the method can adapt to the general treatment scheme of hologram.

Containing watermark host digital hologram in communication process, various attack may be subject to, prove with anti-JPEG compression, Gaussian noise, Filtering Attacks, fouling resistance performance below.

Experiment one: robustness test experiments watermarking images being carried out to JPEG compression in various degree, no matter all show good digital reconstruction effect to hosting object or virtual three-dimensional object, illustrates that watermark hologram has stronger anti-JPEG compressed capability;

Host's hologram when Figure 10 (a) represents that compressibility factor is 0.9 and three-dimensional body cross section digital reproduction result;

Host's hologram when Figure 10 (b) represents that compressibility factor is 0.8 and three-dimensional body cross section digital reproduction result;

Host's hologram when Figure 10 (c) represents that compressibility factor is 0.7 and three-dimensional body cross section digital reproduction result;

Host's hologram when Figure 10 (d) represents that compressibility factor is 0.6 and three-dimensional body cross section digital reproduction result;

Experiment two: anti-Gaussian noise robustness test experiments, under watermark hologram superposition some strength Gaussian noise, still can the information of more clear digital reconstruction hosting object and the watermark of virtual three-dimensional object, illustrate that watermark hologram has certain anti-Gaussian noise ability.

Figure 11 (a) represents that containing watermark host hologram in superposition average is 0, the three-dimensional watermark after the Gaussian noise of variance 0.005 and host's hologram digital reconstruction result;

Figure 11 (b) represents that containing watermark host hologram in superposition average is 0, the three-dimensional watermark after the Gaussian noise of variance 0.01 and host's hologram digital reconstruction result;

Experiment three: carry out various Filtering Attacks robustness test experiments to watermark hologram, still can clear reproduction hosting object and virtual three-dimensional object watermark information under all kinds of Filtering Attacks, illustrates that watermark hologram has good anti-filtering performance.

Figure 12 (a) carries out the digital reconstruction effect of three-dimensional body watermark and host's hologram after two-dimentional Laplce's filtering containing watermark host hologram;

Figure 12 (b) carries out the digital reconstruction effect of three-dimensional body watermark and host's hologram after Laplacian filtering containing watermark host hologram;

Figure 12 (c) represents the digital reconstruction effect of carrying out three-dimensional body watermark and host's hologram after fuzzy contrast boostfiltering containing watermark host hologram;

Figure 12 (d) represents the digital reconstruction effect of carrying out three-dimensional body watermark and host's hologram after Gassian low-pass filter containing watermark host hologram;

Experiment four: to the robustness test experiments of watermark hologram in the stained situation of difference, still can complete reproduction hosting object and virtual three-dimensional object watermark information, illustrates that watermark hologram has certain fouling resistance performance.

Figure 13 (a) is containing the digital reconstruction effect of watermark host hologram three-dimensional body watermark and host's hologram in stained 1 situation;

Figure 13 (b) is containing the digital reconstruction effect of watermark host hologram three-dimensional body watermark and host's hologram in stained 2 situations;

Figure 13 (c) is containing the digital reconstruction effect of watermark host hologram three-dimensional body watermark and host's hologram in stained 3 situations;

Figure 13 (d) is containing the digital reconstruction effect of watermark host hologram three-dimensional body watermark and host's hologram in stained 4 situations;

One to experiment four can be found out by experiment, core of the present invention proposes a kind of virtual three-dimensional object watermarking project with higher-security based on digital hologram, the program has good anti-JPEG compression, Gaussian noise, the performances such as anti-filtering and fouling resistance, the method proposed extends the application scenarios of digital watermarking, by the bearer documents of carrying watermark signal from general audio frequency, picture signal extends to digital hologram, and watermark signal is also expanded to three-dimensional body from one dimension and 2D signal by the application of calculation holographic, realize multiplex and the three-dimensional of watermark signal, in random-phase marks and digital holography, the geometrical structure parameter of optical information transform method and optical system also extends the information conversion method of digital watermarking and improves the security of algorithm in addition.

In sum, a kind of water mark method based on host's digital hologram provided by the invention and device, the cross-section data of virtual three-dimensional object and the diffraction data at plane of vision 1 place are encrypted, the Fresnel diffraction distribution of virtual three-dimensional object described in calculating observation plane 2 place, the watermark generated is made to have higher security, use the watermark embedment host digital hologram of this generation, obtain that there is the high host's digital hologram of security, anti-counterfeiting mark field can be widely used in.

On the basis of host's digital hologram Analysis of Spectrum, to carrier modulation be carried out after the virtual three-dimensional object fresnel holography watermark signal pre-service be encrypted through random phase again and interfere coding, make watermark signal avoid the spectral centroid position of digital hologram zero-order image, original image and conjugate image in spatial frequency domain, then realize the embedding of watermark signal in original host's digital hologram in the method for spatial domain superposition.Owing to adopting random phase to be encrypted, and then improve the security of host's digital hologram.

The hologram directly being intercepted watermark embedment place by spatial domain recovers watermark signal, without the need to the information of original host's hologram, achieves Blind extracting.Optical reproduction simulation test result shows, the method proposed has the good transparency, and when carrying out various attack to host's hologram, no matter be reproduction to host's hologram or the reproduction to three-dimensional body watermark all shows good robustness.

The foregoing is only embodiments of the invention; not thereby the scope of the claims of the present invention is limited; every equivalents utilizing instructions of the present invention and accompanying drawing content to do, or be directly or indirectly used in relevant technical field, be all in like manner included in scope of patent protection of the present invention.

Claims (8)

1. based on a water mark method for host's digital hologram, it is characterized in that, comprise the following steps:

The cross-section data of the virtual three-dimensional object of encryption and diffraction surfaces data;

Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting;

The frequency domain of the Fresnel diffraction distributed data after expansion encryption;

Fresnel diffraction distributed data after modulation expansion;

The zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding, and obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark.

2. a kind of water mark method based on host's digital hologram according to claim 1, it is characterized in that, after " superpose described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtain host's digital hologram signal of embed watermark " step, also comprise:

Host's digital hologram signal of embed watermark obtains host's digital hologram drawing signal at watermark embedment place;

Calculate discrete Fourier transformation with the host's digital hologram drawing signal obtained, obtain digital spectrum;

Filter digital frequency spectrum, obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal;

Calculate the inverse discrete Fourier transform of described spectrum component, obtain the original of Fresnel calculation holographic watermark signal or conjugate image component;

Decipher the original or conjugate image component of described Fresnel calculation holographic watermark signal, obtain the diffraction light wave component of the Fresnel calculation holographic watermark signal of original image or conjugate image;

With the diffraction light wave component digital reconstruction virtual three-dimensional object watermark of the Fresnel calculation holographic watermark signal of described original image or conjugate image.

3. a kind of water mark method based on host's digital hologram according to claim 2, it is characterized in that, described " filter digital frequency spectrum obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal " is specially: use window function on digital spectrum, filter out the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal.

4. a kind of water mark method based on host's digital hologram according to claim 1, is characterized in that, described " cross-section data of encrypted virtual three-dimensional body and diffraction surfaces data; Calculate the Fresnel diffraction distribution of described virtual three-dimensional object, obtain the Fresnel diffraction distributed data after encrypting " be specially:

Adopt cross-section data and the diffraction surfaces data of the virtual three-dimensional object of random-phase marks encryption;

Virtual three-dimensional object after segmentation encryption, obtains multiple cross section;

Random-phase marks is multiplied by each cross section;

Calculate the Fresnel diffraction in the single cross section after being multiplied by random-phase marks;

Discrete Fresnel transform is adopted to calculate the Object light wave COMPLEX AMPLITUDE in the single cross section after being multiplied by random-phase marks;

Calculate the Object light wave COMPLEX AMPLITUDE sum in multiple cross section, obtain the Fresnel diffraction distributed data after encrypting.

5. a kind of water mark method based on host's digital hologram according to claim 1, it is characterized in that, described " frequency domain of the Fresnel diffraction distributed data after expansion encryption; the Fresnel diffraction distributed data after modulation expansion; the zero-order image removing the Fresnel diffraction distributed data after modulation interferes coding; obtain real coding, described real coding is Fresnel calculation holographic watermark signal " is specially:

Calculate the discrete Fourier transformation of described Fresnel diffraction distributed data, obtain digital spectrum;

Null filling is used to expand described digital spectrum;

Calculate the inverse Fourier transform of the digital spectrum after expansion, obtain Fresnel diffraction distributed data;

Plane reference light carrier is used to modulate described Fresnel diffraction distributed data;

Remove the real-valued interference coding of zero-order image of the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal.

6. a kind of water mark method based on host's digital hologram according to claim 1, is characterized in that, described host's digital hologram is off-axis digital holography figure.

7. based on a watermarking device for host's digital hologram, it is characterized in that, comprising: watermark generation module and watermark embedding module;

Described watermark generation module comprises ciphering unit, the first computing unit, expanding element, modulating unit and removal unit;

Described ciphering unit, for cross-section data and the diffraction surfaces data of encrypted virtual three-dimensional body;

Described first computing unit, for calculating the Fresnel diffraction distribution of described virtual three-dimensional object, obtains the Fresnel diffraction distributed data after encrypting;

Described expanding element, for expanding the frequency domain of the Fresnel diffraction distributed data after encryption;

Described modulating unit, for modulating the Fresnel diffraction distributed data after expansion;

Described removal unit, interfere coding for the zero-order image removing the Fresnel diffraction distributed data after modulation, obtain real coding, described real coding is Fresnel calculation holographic watermark signal;

Described watermark embedding module, for superposing described Fresnel calculation holographic watermark signal in host's digital hologram signal, obtains host's digital hologram signal of embed watermark.

8. a kind of watermarking device based on host's digital hologram according to claim 7, it is characterized in that, this device also comprises watermark reconstruction module;

Described watermark reconstruction module comprises acquiring unit, the second computing unit, filter element, the 3rd computing unit, decryption unit and reconstruction unit;

Described acquiring unit, for obtaining host's digital hologram drawing signal at watermark embedment place on host's digital hologram signal of embed watermark;

Described second computing unit, for calculating discrete Fourier transformation with the host's digital hologram drawing signal obtained, obtains digital spectrum;

Described filter element, for filter digital frequency spectrum, obtains the spectrum component of the original or conjugate image of Fresnel calculation holographic watermark signal;

Described 3rd computing unit, for calculating the inverse discrete Fourier transform of described spectrum component, obtains the original of Fresnel calculation holographic watermark signal or conjugate image component;

Described decryption unit, for deciphering the original or conjugate image component of described Fresnel calculation holographic watermark signal, obtains the diffraction light wave component of the Fresnel calculation holographic watermark signal of original image or conjugate image;

Described reconstruction unit, for the diffraction light wave component digital reconstruction virtual three-dimensional object watermark of the Fresnel calculation holographic watermark signal with described original image or conjugate image.