CN104914702A - Optical image hiding device and hiding method - Google Patents

Abstract

The invention relates to an optical image hiding device, comprising an image generating and hiding unit, an image collecting unit and an image reconstructing module. The image generating and hiding unit generates a hologram in which the image of an object to be hidden and a host image are overlapped, the image collecting unit compressively sample the hologram and then sends the hologram data to the image reconstructing module, and the image reconstructing module reconstructs the hologram data. The invention further provides an optical image hiding method. The optical image hiding device and hiding method records the interference-type hologram by a four-step phase shift method, achieves the hiding of the image in an all-optical domain environment, completes the compressive sampling of the hologram through discretely sampling by a single pixel camera system, and achieves image reconstruction by the compressed sensing theory and the holographic reconstructing algorithm.

Description

Optical imagery concealing device and hidden method

Technical field

The invention belongs to optical image security imaging field, be specifically related to a kind of optical imagery concealing device and hidden method.

Background technology

Along with the lifting day by day of information security importance, in a lot of fields, safety of image also becomes more and more important.Safety of image mainly comprises image encryption, image concealing and image watermark.Wherein the process of image concealing is generally to be described as: the subject image A comprising confidential information is embedded in a certain common host image B and transmits, and the surface that receiving end obtains seems the image C still containing image A of closely image B.The image A of confidential information can be obtained comprising after employing any special measures reconstructs image C, thus reach the security requirement of transmission.

Because optical signal processing technology has inherent concurrency, therefore have image taking speed, transmission speed waits outstanding advantage soon, and optics is obtained in all trades and professions to be applied widely, and thing followed optical imagery becomes safely an important research topic.Utilize the interference hologram of coherent light to realize image concealing, thus improve the security of optical image transmission, the feasibility of this thinking have also been obtained related experiment to be proved.

The interference hologram of coherent light has can the feature of recording and reconstruction object phase and complex amplitude information, and the imaging especially for the 3D object of real world, 3D scene or planar graph has significant advantage.The main devices being commonly used to now recorded hologram is digital hologram device, and its cost of manufacture is low, and image taking speed is fast, and recording and reconstruction is flexible.But the big data quantity problem in the storage and transmission of hologram is the principal element of restriction optical imagery safe transmission always.

Along with continuous progress that is scientific and technical and production technology, there is the single pixel camera system adopted based on compressed sensing.Single pixel camera system utilizes single photon detector to gather discrete hologram light signal, is greatly lowered into picture device cost and volume of transmitted data.Meanwhile, various compressive sensing theory and restructing algorithm also improve the transmission of light signal holographic imaging and rebuild efficiency, and then make the hiding application scheme becoming a kind of feasible low cost of optical imagery.

Although effectively can solve the big data quantity problem in hologram image transmitting procedure based on compressive sensing theory and restructing algorithm, the image concealing under the environment of pure light, transmission and optimal reconfiguration system but never came into question.

Summary of the invention

The object of the invention is to overcome shortcoming of the prior art with not enough, under a kind of pure area of light environment is provided, the little optical imagery concealing device of data volume and hidden method.

The present invention is achieved by the following technical solutions: a kind of optical imagery concealing device, comprise Computer image genration and hidden unit, image acquisition units and Image Reconstruction module, described Computer image genration and hidden unit generate the hologram needing the subject image hidden to superpose with host image, after described image acquisition units carries out compression sampling to described hologram, described hologram data is sent to described Image Reconstruction module, described Image Reconstruction module is reconstructed imaging to hologram data.Described Computer image genration and hidden unit comprise one Mach and increase Dare interferometer, electro-optic phase modulator and piezoelectric transducer; Wherein, described Mach increases Dare interferometer and the light beam Wave Decomposition sent from light source is become two-beam ripple, and a branch of be the object light of irradiating object image, the reference light that another bundle is irradiation host image.Along object light light path, described electro-optic phase modulator arranges and is used for loading subject image; Along reference light light path, before described piezoelectric transducer is arranged on host image, and the phase shift of modulation reference light.

Further, described Computer image genration and hidden unit comprise and also include one first neutral density filter and one second neutral density filter; Before being arranged on subject image along the first neutral density filter described in object light light path, and adjust object light light intensity; Before the second neutral density filter is arranged on described piezoelectric transducer described in reference path, and adjust reference light light intensity.

Further, described image acquisition units comprises a Digital Micromirror Device, an image processing module, gathers lens and a single-photon detector; The hologram that described Digital Micromirror Device gathers, first through image processing module compression sampling, is collected described single photon detector and exports as analog electrical signal after then being collected by described collection lens.

Further, four width that described Image Reconstruction module is reconstructed in described Digital Micromirror Device by two step iterative algorithms interfere hologram, and then reconstruct subject image.

Further, this optical imagery concealing device, also includes AD conversion unit and image transmitting unit; Described AD conversion unit converts the electric signal that described image acquisition units is collected to digital signal, and described image transmitting unit is by Image Reconstruction module extremely described for described digital data transmission.

Meanwhile, present invention also offers a kind of optical imagery hidden method, comprise the steps:

S1: the interference hologram of superposition is generated to subject image and host image by Computer image genration and hidden unit;

S2: carry out high speed acquisition by the interference hologram of DMD Digital Micromirror Device to superposition, then the calculation matrix in DMD DMD array plane and the stochastic linear measured value of interfering hologram is calculated, to obtain the sampling compressing hologram, then be gathered into analog electrical signal by single-photon detector;

S3: convert the electrical signal to digital signal, and this digital signal is transmitted;

S4: utilize two step iterative algorithms to reconstruct superposition hologram, and then utilize the complex amplitude information of inverse Fresnel transform algorithm and host image to reconstruct original subject image.

Further, described step S1 is further comprising the steps of:

S11: load subject image by electro-optic phase modulator;

S12: divide four phase modulation by piezoelectric transducer to reference light, the phase place of generating reference light is respectively 0, π, interference light source;

S13: by beam splitter, object light and reference light are interfered, and be recorded as picture by DMD Digital Micromirror Device, obtains the interference hologram of four width superpositions.

Further, described step S4 is further comprising the steps of:

S41: utilize TwIST algorithm (two step iterative algorithms) to reconstruct the interference hologram of the superposition in DMD Digital Micromirror Device;

S42: utilize the complex amplitude information of inverse Fresnel transform algorithm and host image and the method for electricity or light to reconstruct original objects image.

A kind of optical imagery concealing device of the present invention and hidden method, four-stepped switching policy record is utilized to interfere hologram, hiding of image is realized in full area of light environment, utilize the discrete sampling of single pixel camera system to complete the compression sampling of hologram, recycling compressive sensing theory and holographic reconstruction algorithm realization are to Image Reconstruction.

In order to the present invention can be understood more clearly, below with reference to accompanying drawing, elaboration the specific embodiment of the present invention is described.

Accompanying drawing explanation

Fig. 1 is the structured flowchart of optical imagery concealing device of the present invention.

Fig. 2 is the structural representation of optical imagery concealing device of the present invention.

Fig. 3 is the structured flowchart of image acquisition units shown in Fig. 1.

Fig. 4 is the Simulation results figure of optical imagery concealing device of the present invention and hidden method.

Embodiment

Refer to Fig. 1, it is the structured flowchart of optical imagery concealing device of the present invention.This optical imagery concealing device 100 comprises Computer image genration and hidden unit 110, image acquisition units 120, AD conversion unit 130, image transmitting unit 140 and Image Reconstruction module 150.

This Computer image genration and hidden unit 110 generate the hologram of superposition, concrete, and the hologram of this superposition is the subject image that needs to hide and as the interference hologram after the light intensity of the host image of carrier and Phase Stacking.This image acquisition units 120 is gathered into analog electrical signal after carrying out compression sampling to described interference hologram, this analog electrical signal is sent to described AD conversion unit 130 and converts digital signal to, is then sent to Image Reconstruction module 150 through image transmitting unit 140.This Image Reconstruction module 150 utilizes inverse Fresnel transform to reconstruct the interference hologram of described superposition by the method for light or electricity, and then reconstructs original subject image 202.

Please refer to Fig. 2, it is the structural representation of optical imagery concealing device of the present invention.Particularly, this Computer image genration and hidden unit 110 are that the Mach of an improvement increases Dare interferometer, and it comprises laser instrument 111,1 first level crossing 1121,1 first beam splitter 1131, beam splitting lens 114,1 second beam splitter 1132,1 second level crossing 1122,1 first neutral density filter 1161, electro-optic phase modulator 117,1 second neutral density filter 1162, piezoelectric transducer 118 and one the 3rd beam splitter 1133.

Particularly, a branch of linear polarization laser beam that this laser instrument 111 sends is after the collimated reflected of this first level crossing 1121, form the reflected light vertical with incident light, this reflected light is successively through this first beam splitter 1131 and this beam splitting lens 114, then after this second beam splitter 1132, be decomposed into the orthogonal light wave of two bundles, wherein light beam ripple forms object light ψ ₀(ξ, η), in addition a branch of formation reference light ψ _k(ξ, η; φ _r).Described object light ψ ₀(ξ, η) through the collimated reflected of this second level crossing 1122, light intensity is adjusted again through this first neutral density filter 1161, direct irradiation is in subject image 202, modulate through this electric light phase place phase converter 117, after accurately taken the light beam of the photon level of subject image 202 information.Another bundle reference light ψ _k(ξ, η; φ _r) adjust light intensity through this second neutral density filter 1162, then be radiated on host image 204 after this piezoelectric transducer 118 phase modulation, reference light ψ now _k(ξ, η; φ _r) also form the light beam of photon level.The object light ψ of described photon level ₀(ξ, η) and reference light ψ _k(ξ, η; φ _r) after the 3rd beam splitter 1133, define the interference hologram that coaxial interference light also produces the information having superposed this subject image 202 and this host image 204 respectively simultaneously.

Further, object light ψ is supposed ₀(ξ, η) transmitance be radiated in subject image is o (x ₀, y ₀), then after electro-optic phase modulator modulation, pass through o (x ₀, y ₀) COMPLEX AMPLITUDE can be described as:

ψ ₀(ξ,η)＝Frt[O(x ₀,y ₀)]＝A(ξ,η)exp[iφ(ξ,η)],

(wherein, Frt represents o (x ₀, y ₀) Fresnel transform.) this COMPLEX AMPLITUDE describes the information of subject image.

In like manner, host image ψ _k(ξ, η; φ _r) COMPLEX AMPLITUDE can be expressed as:

ψ _h(ξ,η；φ _R)＝A _h(ξ,η)exp[iφ _h(ξ,η)]exp(iφ _R),

$({\mathrm{\φ}}_R=0,\frac{\mathrm{\π}}{2},\mathrm{\π},\frac{3\mathrm{\π}}{2}),$

(wherein, φ _rrepresent phase-stepping.) this COMPLEX AMPLITUDE respectively describes the information of fourth officer host image.

Please refer to Fig. 3, it is the structured flowchart of image acquisition units 120 shown in Fig. 1.This image acquisition units 120 comprises DMD122 (Digital Micromirror Devices, Digital Micromirror Device), image processing module 123, gathers lens 124 and single-photon detector 126.By this image processing module 123 compression sampling after the imaging of the interference hologram superposing generation by Computer image genration and hidden unit 110 on this DMD122, then collected by single-photon detector 126 after the convergence of these collection lens 124.

Particularly, this DMD122 is a kind of fast digital photoswitch reflective array plane be integrated on addressing integrated chip, it is made up of many aluminum small mirrors faces (i.e. micro mirror), each small mirrors face is fixed on hinge, by being controlled the direction of each micro mirror by random number generator (RNG), described micro mirror can do the deflection of+12 °, both direction or-12 ° in the horizontal plane.Its deflection corner is+12 ° and represents 1 in calculation matrix, now ensures that the interference hologram that micro mirror collects is reflected on single-photon detector 126; Deflection corner is-12 ° and represents 0 in calculation matrix, now ensures that the interference hologram that micro mirror collects is reflected in outside single-photon detector 126.The described interference hologram that this Computer image genration and hidden unit 110 generate to project on this DMD122 and by this DMD122 high speed acquisition.This image processing module 123 is by the calculation matrix Φ in calculating DMD122 array plane and interference hologram I _hstochastic linear measured value just obtain compressing the sampling of hologram.Interference hologram after this compression sampling through gathering the convergence of lens 124, and is collected in extremely sensitive single-photon detector 126 and carries out single-point detection, is output into electric signal afterwards.

Now, the light intensity value in DMD122 array plane can be expressed as:

I _H(ξ,η；φ _R)

＝|ψ ₀(ξ,η)+ψ _h(ξ,η；φ _R) ²|

＝A(ξ,η) ²+A _h(ξ,η) ²

+2A(ξ,η)A _h(ξ,η)cos[φ _h(ξ,η)+φ _R-φ(ξ,η)],

$({\mathrm{\φ}}_R=0,\frac{\mathrm{\π}}{2},\mathrm{\π},\frac{3\mathrm{\π}}{2}),$

The output voltage forming the highly sensitive photodiode of this single-photon detector 126 represents:

(wherein, represent that the m in DMD122 plane ties up pseudorandom calculation matrix).

Repeat this process M time, obtaining measured value Y is: Y=[y ₁, y ₂, y ₃, y ₄]=Ψ [I _h1, I _h2, I _h3, I _h4],

(wherein, $\left(I_{H1},I_{H2},I_{H3},I_{H4}\right)=\left[\begin{array}{cccc}{I}_{H11}& I_{H21}& I_{H31}& I_{H41}\\ I_{H12}& I_{H22}& I_{H32}& I_{H41}\\ M& M& M& M\\ I_{H1N}& I_{H2N}& I_{H3N}& I_{H4N}\end{array}\right];$ Ψ ∈ R ^{m × N}the calculation matrix that DMD122 plane obtains, Y ∈ R ^{m × 4}measured value, y _k∈ R ^{m × 1}, I _hk∈ R ^{n × 1}).

In the present embodiment, described DMD122 adopts the D4100DMD model of TI company to be 0.55 " XGA, its true resolution is 1024x 768 (XGA), and speed is maximum reaches 22614 frames per second.Described single-photon detector 126 adopts U.S. Thorlabs company PDA36A-EC detector.

This AD conversion unit 130 utilizes analog to digital converter to convert the analog electrical signal that described single-photon detector 126 detects rear output to digital signal, and transfers to this Image Reconstruction module 150 by described image transmitting unit 140.

Four width that this Image Reconstruction module 150 is reconstructed on DMD122 by the algorithm optimized interfere hologram, and then reconstruct subject image 202.Particularly, TwIST algorithm (two step iterative algorithms) is first utilized to rebuild interference light intensity by solving following optimization problem:

$\begin{array}{ccc}\underset{I_{Hk}}{\min }\frac{\mathrm{\μ}}{2}\left|\right|Y_k-\mathrm{\Φ}{\hat{I}}_{Hk}|{|}_2^2+TV\left({\hat{I}}_{Hk}\right)& s.t.& Y_k={\mathrm{\ΨI}}_{Hk}\end{array},$

Wherein, be l ₂norm, and μ is a constant; a least square term, when with Correlation vector quantization value Y _kbe consistent, so its value is minimum; that the total variation of signal represents, $TV\left({\hat{I}}_{Hk}\right)=\underset{adj.i,j}{\Σ}\left|{\hat{I}}_{Hki}-{\hat{I}}_{Hkj}\right|,$

Subscript i in this formula, j represents in all paired neighbor pixels, so it is only discrete gradient l ₁norm.So far, the fourth officer that algorithm has reconstructed on DMD122 interferes hologram.

Next, utilization obtains four width holograms the recording distance Z1 of the interference light of physical image, the recording distance Z2 of host image interference light, interference light wavelength and object light recover original objects image with the phase place ratio of interference light.The phase information φ (ξ, η) and the amplitude information A (ξ, η) that first calculate subject image figure are as follows:

$\mathrm{\φ}(\mathrm{\ξ},\mathrm{\η})={\tan }^{-1}\frac{{\hat{I}}_{H2}-{\hat{I}}_{H4}}{{\hat{I}}_{H1}-{\hat{I}}_{H3}}+{\mathrm{\φ}}_h(\mathrm{\ξ},\mathrm{\η}),$

$A(\mathrm{\ξ},\mathrm{\η})=\frac{{\[{({\hat{I}}_{H1}-{\hat{I}}_{H3})}^2+{({\hat{I}}_{H2}-{\hat{I}}_{H4})}^2\]}^{1/2}}{4A_h}\·$

(wherein, host image Diffraction fringe distribution φ _hand A _hfour-stepped switching policy is utilized to obtain in advance by increasing in Dare interferometer at the Mach of described improvement).Finally, inverse Fresnel transform is utilized to carry out reconstruction of objects image 202 by the method for electricity or the method for light.In the present embodiment, this Image Reconstruction module 150 is PC or the terminal with calculation processing power.

Based on above-mentioned optical imagery concealing device, a kind of method that the present invention also provides optical imagery to hide:

S1: the interference hologram of superposition is generated to subject image and host image by Computer image genration and hidden unit.

Particularly, this step S1 comprises the following steps:

S11: load subject image by electro-optic phase modulator;

S12: divide four phase modulation by piezoelectric transducer to reference light, generating reference light phase is respectively 0, π, interference light source;

S13: by beam splitter, object light and reference light are interfered, and be recorded as picture by DMD Digital Micromirror Device, obtains the interference hologram of four width superpositions.

Particularly, the principle of this optical imagery hidden method is:

Suppose that the object light transmitance be radiated in subject image is o (x ₀, y ₀), then after electro-optic phase modulator modulation, pass through o (x ₀, y ₀) COMPLEX AMPLITUDE can be described as:

ψ ₀(ξ,η)＝Frt[O(x ₀,y ₀)]＝A(ξ,η)exp[iφ(ξ,η)], (1)

(wherein, Frt represents o (x ₀, y ₀) Fresnel transform.) this COMPLEX AMPLITUDE describes the information of subject image.

In like manner, the COMPLEX AMPLITUDE of host image can be expressed as:

ψ _h(ξ,η；φ _R)＝A _h(ξ,η)exp[iφ _h(ξ,η)]exp(iφ _R),

$({\mathrm{\φ}}_R=0,\frac{\mathrm{\π}}{2},\mathrm{\π},\frac{3\mathrm{\π}}{2}),---\left(2\right)$

(wherein, φ _rrepresent phase-stepping.) this COMPLEX AMPLITUDE respectively describes the information of four width host images.

Therefore, the light intensity value in DMD DMD array plane can be expressed as:

I _H(ξ,η；φ _R)

＝|ψ ₀(ξ,η)+ψ _h(ξ,η；φ _R)| ²

＝A(ξ,η) ²+A _h(ξ,η) ²(3)

+2A(ξ,η)A _h(ξ,η)cos[φ _h(ξ,η)+φ _R-φ(ξ,η)],

$({\mathrm{\φ}}_R=0,\frac{\mathrm{\π}}{2},\mathrm{\π},\frac{3\mathrm{\π}}{2}),$

Light intensity value in this DMD DMD array plane, four width described after subject image and host image superposition interfere hologram.So far, make use of a Mach increasing Dare interferometer improved and just can realize hiding of subject image in full area of light environment.

S2: carry out high speed acquisition by the interference hologram of DMD Digital Micromirror Device to superposition, then the calculation matrix in DMD DMD array plane and the stochastic linear measured value of interfering hologram is calculated, to obtain the sampling compressing hologram, then be gathered into analog electrical signal by single-photon detector.

Further, utilize the characteristic of the micro mirror unit light-operated switch of DMD Digital Micromirror Device, realize the collection to the interference hologram information of superposition and compression sampling.In the present embodiment, the reflected light of DMD DMD array gathers at single-photon detector place through gathering lens, and now, the output voltage forming the highly sensitive photodiode of single-photon detector represents and is:

Wherein, represent that the m in DMD DMD array plane ties up pseudorandom calculation matrix.Once repeat this process M time, can obtain measured value Y is:

Y＝[y ₁,y ₂,y ₃,y ₄]＝Ψ[I _H1,I _H2,I _H3,I _H4], (5)

Wherein, $\left(I_{H1},I_{H2},I_{H3},I_{H4}\right)=\left[\begin{array}{cccc}{I}_{H11}& I_{H21}& I_{H31}& I_{H41}\\ I_{H12}& I_{H22}& I_{H32}& I_{H41}\\ M& M& M& M\\ I_{H1N}& I_{H2N}& I_{H3N}& I_{H4N}\end{array}\right];$ Ψ ∈ R ^{m × N}the calculation matrix that DMD DMD array plane obtains, Y ∈ R ^{m × 4}measured value, y _k∈ R ^{m × 1}, I _hk∈ R ^{n × 1}.

Above, the collection of simulant signal to the described interference hologram information to superposition and compression sampling is just completed.

S3: convert analog electrical signal to digital signal, and this digital signal is transmitted.

S4: utilize TwIST algorithm (two step iterative algorithms) to reconstruct superposition hologram, and then utilize the complex amplitude information of inverse Fresnel transform algorithm and host image to reconstruct original subject image.

Particularly, this step S4 comprises the following steps:

S41: utilize TwIST algorithm (two step iterative algorithms) to reconstruct the interference hologram of the superposition in DMD Digital Micromirror Device;

TwIST algorithm (two step iterative algorithms) is first utilized to rebuild interference wave intensity by solving following optimization problem:

$\begin{array}{ccc}\underset{I_{Hk}}{min}\frac{\mathrm{\μ}}{2}\left|\right|Y_k-\mathrm{\Φ}{\hat{I}}_{Hk}|{|}_2^2+TV\left({\hat{I}}_{Hk}\right)& s.t.& Y_k={\mathrm{\ΨI}}_{Hk}\end{array},---\left(6\right)$

Wherein, be l ₂norm, and μ is a constant; a least square term, when with Correlation vector quantization value Y _kbe consistent, so its value is minimum; that the total variation of signal represents.

$TV\left({\hat{I}}_{Hk}\right)=\underset{adj.i,j}{\Σ}\left|{\hat{I}}_{Hki}-{\hat{I}}_{Hkj}\right|,---\left(7\right)$

Subscript i in this formula, j represents in all paired neighbor pixels, so it is only discrete gradient l ₁norm.

So far, the fourth officer that can reconstruct on DMD DMD array interferes hologram.

S42: utilize the complex amplitude information of inverse Fresnel transform algorithm and host image and the method for electricity or light to reconstruct original objects image.

Now, utilization obtains four width holograms the recording distance Z1 of the interference light of physical image, the recording distance Z2 of host image interference light, interference light wavelength and object light recover original objects image with the phase place ratio of interference light.First, the phase information φ (ξ, η) and the amplitude information A (ξ, η) that calculate subject image figure are as follows:

$\mathrm{\φ}(\mathrm{\ξ},\mathrm{\η})={\tan }^{-1}\frac{{\hat{I}}_{H2}-{\hat{I}}_{H4}}{{\hat{I}}_{H1}-{\hat{I}}_{H3}}+{\mathrm{\φ}}_h(\mathrm{\ξ},\mathrm{\η}),$

$A(\mathrm{\ξ},\mathrm{\η})=\frac{{\[{({\hat{I}}_{H1}-{\hat{I}}_{H3})}^2+{({\hat{I}}_{H2}-{\hat{I}}_{H4})}^2\]}^{1/2}}{4A_h}.---\left(8\right)$

Wherein, host image Diffraction fringe distribution φ _hand A _hfour-stepped switching policy is utilized to obtain in advance by increasing in Dare interferometer at the Mach of described improvement.Finally, the complex amplitude information of inverse Fresnel transform algorithm and host image and the method for electricity or light is utilized to reconstruct original objects image.

Refer to Fig. 4, it is the Simulation results figure of optical imagery concealing device of the present invention and hidden method.In an experiment, the wavelength of helium-neon laser is 632.8nm.Electro-optic phase modulator employing model is the spatial light modulator of HOLOEYE LC2002, and the maximum pixel point of this spatial light modulator is 800 (H) × 600 (V), pel spacing is 32 μm.What original objects image adopted is " sunshape " shape in Microsoft Office 2003 editions, and size is 0.5568cm × 0.5952cm.Host image is letter " C ", and its size is 0.4cm × 0.3cm.Object light is 0.1:1 with the ratio of the amplitude of reference light.Utilize 1/4th slides and 1/2nd slides to modulate stepping phase place in the optical path.Recording distance Z1, Z2 of original objects image and host image are 0.768 meter and 1.004 meters respectively.In this experiment simulation, be recover original objects image the Compression and Hiding hologram of 1024 × 1024 × 22% from sampling rate.Fig. 4 (a) is the interferogram of a width hidden image, Fig. 4 (b) is the Recovery image not through overcompression, and Fig. 4 (c) is be the original objects image recovered the Compression and Hiding hologram of 1024 × 1024 × 22% by optical imagery concealing device of the present invention and hidden method from sampling rate.Through calculating, the Y-PSNR of the restoration result of the data volume of 22% and 100% is respectively 28.4dB and 38.5dB.Result shows, compression optics image concealing can realize in pure area of light.

Compared to prior art, a kind of optical imagery concealing device of the present invention and hidden method, four-stepped switching policy record is utilized to interfere hologram, hiding of image is realized in full area of light environment, utilize the discrete sampling of single pixel camera system to complete the compression sampling of hologram, recycling compressive sensing theory and holographic reconstruction algorithm realization are to Image Reconstruction.

The present invention is not limited to above-mentioned embodiment, if do not depart from the spirit and scope of the present invention to various change of the present invention or distortion, if these are changed and distortion belongs within claim of the present invention and equivalent technologies scope, then the present invention is also intended to comprise these changes and distortion.

Claims (9)

1. an optical imagery concealing device, it is characterized in that: comprise Computer image genration and hidden unit, image acquisition units and Image Reconstruction module, described Computer image genration and hidden unit generate the hologram needing the subject image hidden to superpose with host image, after described image acquisition units carries out compression sampling to described hologram, described hologram data is sent to described Image Reconstruction module, described Image Reconstruction module is reconstructed imaging to hologram data; Described Computer image genration and hidden unit comprise one Mach and increase Dare interferometer, electro-optic phase modulator and piezoelectric transducer; Wherein, described Mach increases Dare interferometer and the light beam Wave Decomposition sent from light source is become two-beam ripple, and a branch of be the object light of irradiating object image, the reference light that another bundle is irradiation host image; Along object light light path, described electro-optic phase modulator arranges and is used for loading subject image, along reference light light path, before described piezoelectric transducer is arranged on host image, and the phase shift of modulation reference light.

2. optical imagery concealing device according to claim 1, is characterized in that: described Computer image genration and hidden unit also comprise one first neutral density filter and one second neutral density filter; Before being arranged on subject image along the first neutral density filter described in object light light path, and adjust object light light intensity; Before the second neutral density filter is arranged on described piezoelectric transducer described in reference path, and adjust reference light light intensity.

3. optical imagery concealing device according to claim 2, is characterized in that: described image acquisition units comprises a Digital Micromirror Device, an image processing module, gathers lens and a single-photon detector; The hologram that described Digital Micromirror Device gathers, through image processing module compression sampling, is collected described single photon detector and exports as analog electrical signal after then being collected by described collection lens.

4. optical imagery concealing device according to claim 3, is characterized in that: four width that described Image Reconstruction module is reconstructed in described Digital Micromirror Device by two step iterative algorithms interfere hologram, and then reconstruct subject image.

5. the optical imagery concealing device according to any one of claim 1-4, is characterized in that: also comprise AD conversion unit and image transmitting unit; Described AD conversion unit converts the electric signal that described image acquisition units is collected to digital signal, and described image transmitting unit is by Image Reconstruction module extremely described for described digital data transmission.

6. an optical imagery hidden method, is characterized in that: comprise the steps

S1: the interference hologram of superposition is generated to subject image and host image by Computer image genration and hidden unit;

S2: carry out high speed acquisition by the interference hologram of Digital Micromirror Device to superposition, then the calculation matrix in DMD array plane and the stochastic linear measured value of interfering hologram is calculated, to obtain the sampling compressing hologram, then be gathered into analog electrical signal by single-photon detector;

S3: convert the electrical signal to digital signal, and this digital signal is transmitted;

S4: utilize two step iterative algorithms to reconstruct superposition hologram, and then utilize the complex amplitude information of inverse Fresnel transform algorithm and host image to reconstruct original subject image.

7. optical imagery hidden method according to claim 6, is characterized in that: described step S1 is further comprising the steps of

S11: load subject image by electro-optic phase modulator;

S12: divide four phase modulation by piezoelectric transducer to reference light, the phase place of generating reference light is respectively interference light source;

S13: by beam splitter, object light and reference light are interfered, and be recorded as picture by Digital Micromirror Device, obtains the interference hologram of four width superpositions.

8. optical imagery hidden method according to claim 7, is characterized in that: described step S4 is further comprising the steps of

S41: the interference hologram utilizing two superpositions of step iterative algorithm reconstruct in Digital Micromirror Device;

S42: utilize the complex amplitude information of inverse Fresnel transform algorithm and host image and the method for electricity or light to reconstruct original objects image.

9. optical imagery hidden method according to claim 8, is characterized in that:

In step sl,

The distribution of described subject image complex amplitude describes, and its Complex Amplitude is

ψ ₀(ξ，η)＝Frt[O(x ₀：y ₀)]＝A(ξ，η)exp[iφ(ξ，η)]：，

Wherein, o (x ₀, y ₀) being through rate, Frt represents o (x ₀, y ₀) Fresnel transform;

The distribution of described host image complex amplitude describes, and its Complex Amplitude is

ψ _h(ξ，η，φ _R)＝A _h(ξ，η)exp[iφ _h(ξ，η)]exp(iφ _R)，

Generate described interference hologram to be expressed as

$\begin{array}{c}{I}_H\left(\mathrm{\ξ},\mathrm{\η};{\mathrm{\φ}}_R\right)={\left|{\mathrm{\ψ}}_0\left(\mathrm{\ξ},\mathrm{\η}\right)+{\mathrm{\ψ}}_h\left(\mathrm{\ξ},\mathrm{\η};{\mathrm{\φ}}_R\right)\right|}^2=A{\left(\mathrm{\ξ},\mathrm{\η}\right)}^2+A_h{\left(\mathrm{\ξ},\mathrm{\η}\right)}^2\\ +2A\left(\mathrm{\ξ},\mathrm{\η}\right)A_h\left(\mathrm{\ξ},\mathrm{\η}\right)\cos \[{\mathrm{\φ}}_h\left(\mathrm{\ξ},\mathrm{\η}\right)+{\mathrm{\φ}}_R-\mathrm{\φ}\left(\mathrm{\ξ},\mathrm{\η}\right)\],\left({\mathrm{\φ}}_R=0,\frac{\mathrm{\π}}{2},\mathrm{\π},\frac{3\mathrm{\π}}{2}\right);\end{array}$

In step s 2,

Analog electrical signal gatherer process is expressed as wherein

{ m in 1,2, L M} representative digit array of micromirror devices plane ties up pseudorandom calculation matrix to m ∈;

Compression sampling procedural representation is Y=[y ₁: y ₂: y ₃: y ₄]=Ψ [I _h1: I _h2: I _h3: I _h4], wherein,

$(I_{H1},I_{H2},I_{H3},I_{H4})=\left[\begin{array}{cccc}{I}_{H11}& I_{H21}& I_{H31}& I_{H41}\\ I_{H12}& I_{H22}& I_{H32}& I_{H41}\\ M& M& M& M\\ I_{H1N}& I_{H2N}& I_{H3N}& I_{H4N}\end{array}\right];$ Ψ ∈ R ^{m × N}the calculation matrix that DMD array plane obtains, Y ∈ R ^{m × 4}measured value, y _k∈ R ^{m × 1}, I _hk∈ R ^{n × 1};

In step s 4 which,

Represent described interference hologram by two-step iteration method reconstruct, be expressed as

$\begin{array}{ccc}\underset{I_{Hk}}{\min }\frac{\mathrm{\μ}}{2}\left|\right|Y_k-\mathrm{\Φ}{\hat{I}}_{Hk}|{|}_2^2+TV\left({\hat{I}}_{Hk}\right)& s.t.& Y_k={\mathrm{\ψI}}_{Hk},\end{array}$

Wherein, be l ₂norm, μ is constant, a least square term,

When with Correlation vector quantization value Y _ktime consistent, its value is minimum, that the total variation of signal represents;

$TV\left({\hat{I}}_{Hk}\right)=\underset{adj.i,j}{\Σ}\left|{\hat{I}}_{Hki}-{\hat{I}}_{Hkj}\right|,$

Wherein, i, j represent in all paired neighbor pixels, it is discrete gradient l ₁norm;

Reconstructing described subject image procedural representation by inverse Fresnel transform algorithm is

$\mathrm{\φ}(\mathrm{\ξ},\mathrm{\η})={\tan }^{-1}\frac{{\hat{I}}_{H2}-{\hat{I}}_{H4}}{{\hat{I}}_{H1}-{\hat{I}}_{H3}}+{\mathrm{\φ}}_h(\mathrm{\ξ},\mathrm{\η}),A(\mathrm{\ξ},\mathrm{\η})=\frac{{\[{\left({\hat{I}}_{H1}-{\hat{I}}_{H3}\right)}^2+{\left({\hat{I}}_{H2}-{\hat{I}}_{H4}\right)}^2\]}^{1/2}}{4A_h},$

Wherein, described host image Diffraction fringe distribution φ _hand A _hfour-stepped switching policy is utilized to obtain in advance.