CN113343268A - A multi-3D scene encryption and decryption method with controllable amplification and decryption - Google Patents

Abstract

The invention discloses a multi-three-dimensional scene encryption and decryption method with controllable amplification and decryption. The object field information of each layered layer of each three-dimensional scene is expanded and zero-filled, the Fresnel inverse diffraction light wave is calculated, and the spherical wave is multiplied to obtain the Amplified and reconstructed diffracted lightwave signals at each level; superimposed the amplified and reconstructed diffracted lightwave signals of each level to obtain the amplified and reconstructed diffracted lightwave signals of each three-dimensional scene at each level; the composite diffracted lightwave signals obtained by adding the diffracted lightwave signals of each three-dimensional scene and then superimposed A complex noise signal obtains a composite lightwave signal of the sum of two phase functions; one of the phase functions is used as a public encrypted phase template after binary phase processing; the residual component of the composite lightwave signal minus the binary phase template component is combined with the interference suppression signal A complex signal for decryption is formed, and the decrypted phase template 1 and the decrypted phase template 2 decomposed by the inverse operation of Fresnel diffraction of the complex signal for decryption are combined with the common binary encrypted phase template to calculate the Fresnel diffraction at a specific distance, and obtain the corresponding three-dimensional All levels of the scene are enlarged, decrypted and reconstructed. The present invention has good safety and magnification reconstruction effect.

Description

A multi-3D scene encryption and decryption method with controllable amplification and decryption

technical field

The invention relates to the technical field of three-dimensional scene encryption and decryption, in particular to a multi-three-dimensional scene encryption and decryption method with controllable amplification and decryption.

Background technique

3D scenes described by depth maps and digital images are important information sources in the fields of machine vision, 3D TV, 3D movies, 3D calls, 3D maps, 3D games, and telemedicine. The rapid development of computer and Internet technology brings convenience and also brings the security problem of 3D scene digital carrier. In applications such as multi-user authentication, content distribution, and improving the efficiency of secret information transmission, multiple 3D scene encryption needs to be solved. question. In addition, for the low-resolution original 3D scene, it is necessary to solve the problem of decryption, enlargement and reconstruction of the 3D scene.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-3D scene encryption and decryption method with controllable amplification and decryption.

The technical scheme adopted in the present invention is:

A kind of multi-dimensional scene encryption and decryption method of controllable amplification and decryption, it comprises encryption step and decryption step, and concrete steps are as follows:

Encryption steps:

Step 1-1, layering a single 3D scene in combination with depth information;

Step 1-2, the object field information of each layer is expanded and zero-filled according to the decryption magnification requirement, and the Fresnel inverse diffraction is calculated for the layer information after the expansion and zero-filling;

In steps 1-3, the Fresnel inverse diffracted light wave is multiplied by the spherical wave to obtain the amplified and reconstructed diffracted light wave signal at the level;

Steps 1-4, superimposing the amplified and reconstructed diffracted light wave signals of each layer to obtain the amplified and reconstructed diffracted light wave signals of each layer corresponding to a single three-dimensional scene;

Steps 1-5, respectively calculate and obtain the amplified and reconstructed diffracted lightwave signals of each three-dimensional scene;

Steps 1-6, adding the diffracted lightwave signals from each three-dimensional scene to obtain a composite diffracted lightwave signal containing multiple three-dimensional scenes for amplification and decryption, and the composite diffracted lightwave signal is superimposed with a complex noise signal to form a multiple three-dimensional scene. The composite lightwave signal in the form of complex noise;

Step 1-7, the composite light wave signal is decomposed into the sum of two phase functions, and a phase function is arbitrarily taken and its phase is quantized into a binary phase, and this binary phase function is used as a public encrypted binary phase template;

Steps 1-8, combine the remaining components after subtracting the binary phase template component from the composite lightwave signal and the interference suppression signal of each three-dimensional scene to form a complex signal for decryption corresponding to each three-dimensional scene, and the complex signal for decryption has a distance of Z1. After the inverse operation of Fresnel diffraction, it is decomposed into decrypted phase template 1 and decrypted phase template 2;

Decryption steps:

1) utilize the deciphering phase template 1 and deciphering phase template 2 corresponding to each three-dimensional scene to calculate the Fresnel diffraction that the distance is z1;

2) Calculate the Fresnel diffraction of a specific diffraction distance with the added signal of the diffracted light wave signal in the decryption step 1 and the public encrypted binary phase template to obtain an enlarged and reconstructed image of each layer of the three-dimensional scene.

Further, as a preferred embodiment, the calculation steps for the amplified and reconstructed three-dimensional scene diffracted light wave signal S _m in steps 1-4 are as follows:

In step 1-4-1, the virtual surface light source signal E _i (x, y) is obtained by calculating the Fresnel inverse diffraction with the distance d _i and the light wavelength λ, and the calculation formula is:

Among them, f _i (x ₀ , y ₀ ) represents the layered image of the ith layer of a single three-dimensional scene after expansion and zero-filling, and d _i represents the Fresnel diffraction distance between the layer and the observation plane;

Step 1-4-2, the digital spherical wave signal formula is:

Among them, R _c is the radius of curvature, and the relationship between it and the magnification is:

Among them, γ represents the magnification.

Step 1-4-3, calculate and obtain the three-dimensional scene diffracted light wave signal S _m used for amplification and reconstruction, and the calculation formula is as follows:

Among them, E _i (x, y) is the virtual surface light source signal, L(x, y) is the curvature radius of the spherical wave; i represents the ith layer of a single 3D scene; N is the number of layers in a single 3D scene.

Further, as a kind of preferred embodiment, the calculation formula of the composite light wave signal S of complex noise form in step 1-6 is as follows:

为随机幅度和随机相位信号，Re^jφ表示复噪声信号。Among them, M represents the number of 3D scenes, m represents the mth 3D scene, S _m represents the diffracted light wave signal used for amplification and reconstruction of the mth 3D scene, R and

is the random amplitude and random phase signal, Re ^jφ represents the complex noise signal.

Further, as a preferred embodiment, the specific steps of steps 1-7 are as follows:

Step 1-7-1, decompose the composite light wave signal into the form of adding two phase functions, namely

in,

Step 1-7-2, binarize the phase f ₁ to form a binary encrypted phase E, that is

E=bin(f ₁ ) (9)

Among them, bin( ) represents the binarization process,

In step 1-7-3, the binary encrypted phase template e ^{jE is} used as a common encrypted phase template, and the binary encrypted phase template e ^jE contains common information of multiple three-dimensional scenes.

Further, as a preferred embodiment, the specific steps of steps 1-8 are:

Step 1-8-1, obtain the complex signal D for decryption of the Kth three-dimensional scene, which is expressed as:

In step 1-8-2, the complex signal D for decryption is subjected to the inverse operation of Fresnel diffraction with a distance of Z1 to perform equal-modular decomposition of the light vector, and the decrypted phase template 1 and the decrypted phase template 2 are obtained, and the specific expressions are:

in,

Further, as a kind of preferred embodiment, the calculation formula of the Fresnel diffraction distance of the i-th layer three-dimensional scene in step 2-1 is as follows:

where d _min represents the distance from the nearest object surface to the observation surface, d _max represents the distance from the farthest object surface to the observation surface, and Di is the depth value of the i-th layer 3D scene.

Further, as a kind of preferred embodiment, in step 2-1, the calculation formula of each level of three-dimensional scene amplification and reconstruction signal is as follows:

Further, as a kind of preferred embodiment, the quality of reconstructing three-dimensional scene is evaluated with correlation coefficient NC, and correlation coefficient formula is as follows:

Wherein, O represents the original three-dimensional scene, and R is the three-dimensional scene decrypted by using the binary phase template and the first and second decrypted phase templates.

Further, as a preferred embodiment, the decryption step partially reconstructs the three-dimensional scene by decrypting the virtual optical path; the decrypted virtual optical path includes two beam splitters and a photodetector CCD, and the two beam splitters and the photodetector CCD are arranged in sequence. , the decryption phase template 1 and the decryption phase template 2 are respectively set on different light incident surfaces of the first beam splitter, and the light exit surface of the first beam splitter is connected to the light incident of the second beam splitter through the spatial light modulator The binary encryption phase template E is set at the specific light incident surface of the second beam splitter, and the light exit surface of the second beam splitter is set corresponding to the CCD of the photodetector.

The present invention adopts the above technical scheme, first, a single three-dimensional scene is combined with depth information layering; the object field information of each layer is expanded and zero-filled according to the decryption magnification requirement, and Fresnel inverse diffraction is calculated for the layer information after the expansion and zero-filling; The diffracted light wave is multiplied by the spherical wave to obtain the diffracted light wave signal used for the amplification and reconstruction of this layer; the amplified and reconstructed diffracted light wave signal of each layer is superimposed to obtain the diffracted light wave signal used for the amplification and reconstruction of each layer of a single three-dimensional scene; the same method is used to obtain other The diffracted lightwave signal used for amplification and reconstruction of the three-dimensional scene; the diffracted lightwave signal from each three-dimensional scene is added to obtain a composite diffracted lightwave signal containing multiple three-dimensional scenes that can be used for amplification and decryption, and the composite diffracted lightwave signal is superimposed with a complex noise The signal forms a composite lightwave signal in the form of complex noise containing multiple three-dimensional scenes. The composite lightwave signal is decomposed into the sum of two phase functions, and any phase function is taken to quantize its phase into a binary phase, which is used as a common encrypted binary phase template. Combining the residual component after subtracting the binary phase template component from the composite lightwave signal and the interference suppression signal of each 3D scene to form a complex signal for decryption corresponding to each 3D scene, the complex signal is subjected to the inverse operation of Fresnel diffraction with a distance of Z1 It is then decomposed into decrypted phase template 1 and decrypted phase template 2. Using the decrypted phase template 1, decrypted phase template 2 and the public binary encrypted phase template corresponding to the three-dimensional scene in the Fresnel domain to calculate the Fresnel diffraction at a specific distance after the cascade addition, the three-dimensional scene can be obtained. All levels are enlarged, decrypted and reconstructed. The test results show that the proposed method has good safety and magnified reconstruction effect. The lack of the public binary encrypted phase template or the decrypted phase template will lead to the failure of 3D scene reconstruction, while the binary encrypted phase template can still reconstruct the 3D scene to a certain extent under the condition of superimposed Gaussian noise with a certain intensity. Pass filtering and contrast enhancement filtering also show strong anti-attack performance.

Description of drawings

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments;

Fig. 1 is the multi-dimensional scene encryption flow chart of the present invention;

Fig. 2 is the three-dimensional scene decryption flow chart of the present invention;

Fig. 3 is the three-dimensional scene layered model of the present invention;

Fig. 4 is a schematic diagram of generating a three-dimensional scene i amplification and decryption diffracted light wave signal;

Fig. 5 is the multi-3D scene encryption and decryption principle block diagram of the present invention;

Fig. 6 is the decryption virtual light path diagram of the present invention;

Fig. 7 is the original three-dimensional scene and the layered image of the present invention;

Fig. 8 is the public binary encryption phase template of the present invention;

Fig. 9 is the first and second decryption phase templates of decrypting each three-dimensional scene of the present invention;

10 is each three-dimensional scene reconstructed by the decrypted phase template according to the present invention;

11 is a reconstructed image of the three-dimensional scene 1 under the combination of different phase templates of the present invention;

Fig. 12 is the anti-attack performance of the binary encryption phase template of the present invention;

13 is a schematic diagram showing the comparison of anti-noise performance under different quantization bits of the binary encryption phase template of the present invention;

14 is a reconstructed image of the 3D scene 1 when the decryption phase template D1 error rate of the present invention is 0.2%;

Fig. 15 is a reconstructed image of the 3D scene 1 when the error rate of the decrypted phase template D2 of the scene 1 is 0.2%.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application.

The key idea of the present invention is: a multi-3D scene encryption and decryption method based on Fresnel domain cascaded phase template decomposition and controllable amplification and decryption. First, a single 3D scene is layered with depth information; the object field information of each layer is expanded and zero-filled according to the decryption magnification requirement, and the Fresnel inverse diffraction is calculated for the layer information after the expansion and zero-filling; the inverse diffracted light wave is multiplied by the spherical wave Obtain the diffracted light wave signal used for amplification and reconstruction of this layer; superimpose the amplified and reconstructed diffracted light wave signal of each layer to obtain the diffracted light wave signal used for the amplification and reconstruction of each layer of a single 3D scene; use the same method to obtain other 3D scenes for amplification and reconstruction. The diffracted lightwave signals from each 3D scene are added together to obtain a composite diffracted lightwave signal that contains multiple 3D scenes and can be used for amplification and decryption. The composite diffracted lightwave signal is superimposed with a complex noise signal to form multiple 3D scenes. The complex lightwave signal in the form of complex noise. The composite light wave signal is decomposed into the sum of two phase functions, and any phase function is taken to quantize its phase into a binary phase, which is used as a public encrypted binary phase template. Combining the residual component after subtracting the binary phase template component from the composite lightwave signal and the interference suppression signal of each 3D scene to form a complex signal for decryption corresponding to each 3D scene, the complex signal is subjected to the inverse operation of Fresnel diffraction with a distance of Z1 It is then decomposed into decrypted phase template 1 and decrypted phase template 2. Using the decrypted phase template 1, decrypted phase template 2 and the public binary encrypted phase template corresponding to the three-dimensional scene in the Fresnel domain to calculate the Fresnel diffraction at a specific distance after the cascade addition, the three-dimensional scene can be obtained. All levels are enlarged, decrypted and reconstructed. The test results show that the proposed method has good safety and magnification reconstruction effect. The lack of the public binary encrypted phase template or the decrypted phase template will lead to the failure of 3D scene reconstruction, while the binary encrypted phase template can still reconstruct the 3D scene to a certain extent under the condition of superimposed Gaussian noise with a certain intensity. Pass filtering and contrast enhancement filtering also show strong anti-attack performance. It can be widely used in the field of data security.

As shown in one of FIG. 1 to FIG. 15 , the present invention discloses a multi-3D scene encryption method based on Fresnel domain cascaded phase template decomposition and controllable amplification and decryption, which includes an encryption step and a decryption step, and the specific steps are as follows :

Encryption steps:

Step 1-1, first a single 3D scene is layered with depth information;

Step 1-2, the object field information of each layer is expanded and zero-filled according to the decryption magnification requirement, and the Fresnel inverse diffraction is calculated for the layer information after the expansion and zero-filling;

Steps 1-3, multiply the inverse diffracted light wave by the spherical wave to obtain the diffracted light wave signal used for amplification and reconstruction at the layer;

Steps 1-4, superimposing the amplified and reconstructed diffracted light wave signals of each layer to obtain diffracted light wave signals used for the amplification and reconstruction of each layer of a single three-dimensional scene;

Steps 1-5, using the same method to obtain diffracted light wave signals for amplification and reconstruction of other three-dimensional scenes;

Steps 1-6, add the diffracted lightwave signals from each three-dimensional scene to obtain a composite diffracted lightwave signal that includes multiple three-dimensional scenes and can be used for amplification and decryption, and the composite diffracted lightwave signal is superimposed with a complex noise signal to form a plurality of three-dimensional scenes. The complex lightwave signal in the form of complex noise.

Steps 1-7, decompose the composite lightwave signal into the sum of two phase functions, select any phase function to quantize its phase into a binary phase, and use the binary phase function as a public encrypted binary phase template.

Steps 1-8, combine the residual component after subtracting the binary phase template component from the composite lightwave signal and the interference suppression signal of each three-dimensional scene to form a complex signal for decryption corresponding to each three-dimensional scene, and the complex signal passes through a Philippine distance of Z1. After the inverse operation of Neel diffraction, it is decomposed into decrypted phase template 1 and decrypted phase template 2.

Referring to Figure 2, the decryption steps include:

Step 2-1, using the decrypted phase template 1 and the decrypted phase template 2 corresponding to each three-dimensional scene to calculate the Fresnel diffraction with a distance of z1;

Step 2-2, calculates the Fresnel diffraction of specific diffraction distance with the diffracted light wave signal in decryption step 1 and the signal after the public encryption phase template is added to obtain three-dimensional scene magnification and reconstruction image at each level;

The concrete principle of the present invention is described in detail below:

Referring to FIG. 3 and FIG. 4 , the Fresnel diffracted light wave distribution of the three-dimensional scene that can be used for magnification and reconstruction is obtained by using the layered model of the three-dimensional scene and computational holography. Let the depth map of the 3D scene be D(x, y), which is represented by an 8-bit grayscale image with a value of [0, 255]. The histogram of the depth map is calculated, and the 3D scene is divided into multiple layers according to the multi-threshold segmentation method combined with the statistical characteristics of the histogram, and the depth value of the layer is determined according to the focused object field information of each layer. The Fresnel diffraction distance of the i-th layer three-dimensional scene can be expressed by formula (1). where d _min represents the distance from the nearest object surface to the observation surface, and d _max represents the distance from the farthest object surface to the observation surface. where Di is the depth value of the i-th 3D scene.

FIG. 4 is a schematic diagram of generating a diffracted light wave signal for amplifying and decrypting by means of computational holography in a three-dimensional scene. Figure 3 is a layered model of a three-dimensional scene, and Figure 4 is a schematic diagram of the generation principle of the amplified and decrypted diffracted light wave signal of the three-dimensional scene.

Let f _i (x ₀ , y ₀ ) represent the layered image of the ith layer of a single three-dimensional scene after expansion and zero-filling, and d _i represents the Fresnel diffraction distance between the layer and the observation plane; the calculated distance is d _i , the Fresnel inverse diffraction of the light wavelength λ, and the virtual surface light source signal is obtained.

Defining the digital spherical wave signal L(x, y), the relationship between the radius of curvature of the spherical wave and the magnification is represented by formula (4), where γ represents the magnification.

The diffracted light wave signal of the 3D scene for magnification and reconstruction can be expressed by formula (5).

Please refer to FIG. 5 . FIG. 5 is a schematic block diagram of generating a multi-3D scene encryption/decryption signal. According to formula (5), the diffracted light wave signal S _m for each three-dimensional scene can be obtained for amplification and reconstruction. Suppose there are M three-dimensional scenes in total, and the subscript m represents the mth three-dimensional scene; add the diffracted light wave signals from each three-dimensional scene. A composite diffracted lightwave signal containing multiple three-dimensional scenes that can be used for amplification and decryption is obtained, and a complex noise signal is superimposed on the composite diffracted lightwave signal to form a complex lightwave signal in the form of complex noise containing multiple three-dimensional scenes. The composite lightwave signal in the form of complex noise can be expressed as:

为随机幅度和随机相位信号。where R and

are random amplitude and random phase signals.

The composite lightwave signal is decomposed into the sum of two phase functions, and any phase function is taken to quantize its phase into a binary phase, and the binary phase function is used as a common encrypted binary phase template.

S can be decomposed into the form of the addition of two phase functions, namely

in

The phase f ₁ is binarized to form a binary encrypted phase E.

E=bin(f ₁ ) (9)

where bin(·) represents the binarization process. The binary encrypted phase template e ^jE contains common information of multiple three-dimensional scenes, and is used as a public encrypted phase template.

The residual components after subtracting the binary phase template component from the composite lightwave signal are combined with the interference suppression signals of each three-dimensional scene to form a complex signal for decryption corresponding to each three-dimensional scene. The complex signal D used for decryption of the Kth three-dimensional scene can be expressed as:

After the complex signal D is subjected to the inverse operation of Fresnel diffraction with a distance of Z1, the equal-modular decomposition of the light vector is carried out, and the decrypted phase template 1 and the decrypted phase template 2 are obtained.

in

Please refer to FIG. 6 , FIG. 6 is a virtual light path diagram for magnifying and decrypting each three-dimensional scene. Use the decrypted phase template D1 and the decrypted phase template D2 corresponding to each three-dimensional scene to calculate the Fresnel diffraction with a distance of z1; the obtained diffracted lightwave signal and the signal obtained by adding the common encrypted phase template E calculate the diffraction distance of γd _i . Fresnel diffraction is used to obtain magnified reconstructed images of each layer of a three-dimensional scene. The signal on the CCD plane can be represented by formula (10), where λ is the wavelength of light. BS stands for beam splitter and SLM stands for spatial light modulator.

The quality of the reconstructed 3D scene can be evaluated by the correlation coefficient, which is defined as formula (13).

where O represents the original 3D scene and R represents the reconstructed 3D scene.

Please refer to Figures 7, 7 and 8, Figure 7 is the original grayscale image and depth map of three 3D scenes and the layered image obtained according to the histogram characteristics of the depth map, and the image size is 128*128 points. Figure 8 is a public binary encrypted phase template generated by three three-dimensional scenes according to the method, each three-dimensional scene is set at a magnification of 4 times, and the size is 512*512 points. Fig. 9 is the first and second decryption phase templates obtained by this method for each three-dimensional scene amplification and decryption; wherein the distances between the three levels of scene 1 and the observation plane are: 475mm, 485mm, 495mm; the three levels of scene 2 are respectively: 475mm, 485mm, 495mm The distances from the observation plane are: 474mm; 485mm; 494mm; the distances between the three levels of scene 3 and the observation plane are: 474mm; 481mm; 494mm; the light wavelength λ is 532nm.

Please refer to FIG. 10 , the three-dimensional scene is reconstructed by using the public binary encrypted phase template and the first and second decrypted phase templates for decrypting each three-dimensional scene. The wavelength λ=532nm; the reconstruction distances of the three levels of the 3D scene 2 are: 1896mm, 1940mm, 1980mm, and the wavelength λ=532nm; the reconstruction distances of the three levels of the 3D scene 3 are 1884mm, 1924mm, 1976mm, and the wavelength λ=532nm. The magnification of each reconstruction level of the 3D scene is 4, and the size of the reconstructed image surface is 512*512 points; the reconstructed image shows that the focused level is clear, and the unfocused level is blurred, which is consistent with the characteristics of holographic three-dimensional display.

The calculated similarity between the 3D scene reconstructed using the encrypted phase template and the decrypted phase template and the original 3D scene are: 3D scene 1: 0.8342; 3D scene 2: 0.8066; 3D scene 3: 0.8219.

For any 3D scene, the absence of either the phase template for encryption or decryption will cause the reconstruction of the 3D scene to fail. Please refer to FIG. 11 . FIG. 11 takes the three-dimensional scene 1 as an example to show the decryption results under the combination of different phase templates. Wherein E represents the public binary encryption phase template, D1 represents the first decryption phase template, and D2 represents the second decryption phase template.

Please refer to FIG. 12. FIG. 12 is a reconstructed image of the three-dimensional scene 1 under various attack situations of the binary encrypted phase template.

Please refer to Fig. 13. Fig. 13 takes the 3D scene 1 as an example. The comparison of the anti-noise performance of the common binary encryption phase template with different quantization bits shows that in the case of superimposing Gaussian noise and multiplicative interference of the same intensity, using The binary encrypted phase template has a clearer reconstruction effect.

Please refer to Fig. 14 and Fig. 15. Fig. 14 is the reconstructed image of 3D scene 1 when the error rate of the decrypted phase template D1 of scene 1 is 0.2%. Fig. 15 is the reconstructed image of 3D scene 1 when the error rate of the decrypted phase template D2 of scene 1 is 0.2%. Like, exhibit good key sensitivity.

The present invention adopts the above technical scheme, first, a single three-dimensional scene is combined with depth information layering; the object field information of each layer is expanded and zero-filled according to the decryption magnification requirement, and Fresnel inverse diffraction is calculated for the layer information after the expansion and zero-filling; The diffracted light wave is multiplied by the spherical wave to obtain the diffracted light wave signal used for the amplification and reconstruction of this layer; the amplified and reconstructed diffracted light wave signal of each layer is superimposed to obtain the diffracted light wave signal used for the amplification and reconstruction of each layer of a single three-dimensional scene; the same method is used to obtain other The diffracted lightwave signal used for amplification and reconstruction of the three-dimensional scene; the diffracted lightwave signal from each three-dimensional scene is added to obtain a composite diffracted lightwave signal containing multiple three-dimensional scenes that can be used for amplification and decryption, and the composite diffracted lightwave signal is superimposed with a complex noise The signal forms a composite lightwave signal in the form of complex noise containing multiple three-dimensional scenes. The composite lightwave signal is decomposed into the sum of two phase functions, and any phase function is taken to quantize its phase into a binary phase, which is used as a common encrypted binary phase template. Combining the residual component after subtracting the binary phase template component from the composite lightwave signal and the interference suppression signal of each 3D scene to form a complex signal for decryption corresponding to each 3D scene, the complex signal is subjected to the inverse operation of Fresnel diffraction with a distance of Z1 It is then decomposed into decrypted phase template 1 and decrypted phase template 2. Using the decrypted phase template 1, decrypted phase template 2 and the public binary encrypted phase template corresponding to the three-dimensional scene in the Fresnel domain to calculate the Fresnel diffraction at a specific distance after the cascade addition, the three-dimensional scene can be obtained. All levels are enlarged, decrypted and reconstructed. The test results show that the proposed method has good safety and magnified reconstruction effect. The lack of the public binary encrypted phase template or the decrypted phase template will lead to the failure of 3D scene reconstruction, while the binary encrypted phase template can still reconstruct the 3D scene to a certain extent under the condition of superimposed Gaussian noise with a certain intensity. Pass filtering and contrast enhancement filtering also show strong anti-attack performance.

Obviously, the described embodiments are some, but not all, embodiments of the present application. The embodiments in this application and features in the embodiments may be combined with each other without conflict. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the detailed description of the embodiments of the application is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the protection scope of the present application.

Claims (9)

1. A controllable amplification and decryption multi-three-dimensional scene encryption and decryption method is characterized by comprising the following steps: the method comprises an encryption step and a decryption step, and comprises the following specific steps:

an encryption step:

step 1-1, layering a single three-dimensional scene by combining depth information;

step 1-2, performing amplitude expansion zero padding on each layer object field information according to the decryption amplification rate requirement, and calculating Fresnel inverse diffraction on layer information after amplitude expansion zero padding;

1-3, multiplying the Fresnel inverted diffraction light wave by a spherical wave to obtain an amplified and reconstructed diffraction light wave signal of the layer;

step 1-4, superposing the amplified and reconstructed diffracted light wave signals of all layers to obtain the amplified and reconstructed diffracted light wave signals of all layers corresponding to a single three-dimensional scene;

step 1-5, respectively calculating to obtain diffraction light wave signals of amplified reconstruction of each three-dimensional scene;

step 1-6, adding the diffraction light wave signals from each three-dimensional scene to obtain a composite diffraction light wave signal which comprises a plurality of three-dimensional scenes and is used for amplification and decryption, and superposing a complex noise signal on the composite diffraction light wave signal to form a composite light wave signal in a complex noise form comprising a plurality of three-dimensional scenes;

step 1-7, decomposing the composite lightwave signal into the sum of two phase functions, quantizing the phase of any one phase function into a binary phase, and using the binary phase function as a common encrypted binary phase template;

step 1-8, combining the residual component of the composite light wave signal minus the binary phase template component with the interference suppression signals of each three-dimensional scene to form a decryption complex signal corresponding to each three-dimensional scene, and decomposing the decryption complex signal into a decryption phase template 1 and a decryption phase template 2 after Fresnel diffraction inverse operation with the distance of Z1;

and (3) decryption:

step 2-1, calculating a Fresnel diffraction light wave signal with a distance z1 by using the decryption phase template 1 and the decryption phase template 2 corresponding to each three-dimensional scene;

and 2-2, calculating Fresnel diffraction of a specific diffraction distance by using a Fresnel diffraction light wave signal obtained by decryption calculation and a signal obtained by adding a public encryption binary phase template to obtain an amplified reconstructed image of each layer of the three-dimensional scene.

2. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 1, characterized in that: three-dimensional scene diffraction light wave signal S for amplification reconstruction in steps 1-4_mThe calculation steps are as follows:

step 1-4-1, calculating the distance as d_iAnd obtaining a virtual surface light source signal E by Fresnel inverse diffraction with the optical wavelength of lambda_i(x, y) which is calculated by the formula:

wherein ,f_i(x₀,y₀) Representing a dilated zero-filled hierarchical image of the ith level of a single three-dimensional scene, d_iRepresenting the Fresnel diffraction distance of the layer from the observation plane;

step 1-4-2, the digital spherical wave signal formula is as follows:

wherein ,R_cThe relationship between radius of curvature and magnification is:

wherein γ represents a magnification;

step 1-4-3, calculating to obtain three-dimensional scene diffraction light wave signal S for amplification reconstruction_mThe calculation formula is as follows:

wherein ,E_i(x, y) is a virtual surface light source signal, and L (x, y) is a digital spherical wave; i represents the ith layer of the single three-dimensional scene; and N is the number of layers of a single three-dimensional scene.

3. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 2, characterized in that: the calculation formula of the complex optical wave signal S in the form of complex noise in steps 1-6 is as follows:

wherein M represents the number of three-dimensional scenes, M represents the mth three-dimensional scene, S_mDiffracted lightwave signal for amplified reconstruction, R and

for random amplitude and random phase signals, Re^jφRepresenting a complex noise signal.

4. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 3, characterized in that: the specific steps of steps 1-7 are as follows:

step 1-7-1, the composite lightwave signal is decomposed into a form of adding two phase functions, namely

wherein ,

step 1-7-2, phase f₁Binarizing to form a binary sumIn a dense phase E, i.e.

E＝bin(f₁) (9)

Wherein bin (·) represents binarization processing;

step 1-7-3, the binary encryption phase template e^jEAs a common encryption phase template, a binary encryption phase template e^jEContains information common to a plurality of three-dimensional scenes.

5. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 4, wherein: the steps 1-8 comprise the following specific steps:

step 1-8-1, obtaining a complex signal D for decryption of a Kth three-dimensional scene, which is expressed as:

step 1-8-2, after performing fresnel diffraction inverse operation with a distance of Z1, performing light vector equimodular decomposition on the complex signal D for decryption to obtain a decrypted phase template 1 and a decrypted phase template 2, wherein the specific expression is as follows:

wherein ,

6. the encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 5, wherein: the calculation formula of the Fresnel diffraction distance of the ith layer of three-dimensional scene in the step 2-1 is as follows:

wherein d_minIndicating the distance from the nearest object plane to the observation plane, d_maxRepresents the farthest object plane to view plane distance, where di is the depth value of the ith layer of the three-dimensional scene.

7. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 6, wherein: the calculation formula of the amplified reconstructed signals of all layers of the three-dimensional scene in the step 2-1 is as follows

8. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 7, wherein: the quality of the reconstructed three-dimensional scene is evaluated by a correlation coefficient NC, and the correlation coefficient formula is as follows:

wherein, O represents the original three-dimensional scene, and R is the three-dimensional scene decrypted by the binary phase template and the first and second decryption phase templates.

9. The encryption and decryption method for the controllable amplification and decryption of the multiple three-dimensional scenes according to claim 1, characterized in that: in the decryption step, three-dimensional scene reconstruction is carried out through a decrypted virtual light path; the virtual decryption light path comprises two beam splitters and a photoelectric detector CCD, the two beam splitters and the photoelectric detector CCD are sequentially arranged, a decryption phase template 1 and a decryption phase template 2 are respectively arranged on different light incoming surfaces of a first beam splitter, a light outgoing surface of the first beam splitter is in butt joint with a light incoming surface of a second beam splitter through a spatial light modulator, a binary encryption phase template E is arranged at a specific light incoming surface of the second beam splitter, and the light outgoing surface of the second beam splitter is arranged corresponding to the photoelectric detector CCD.

Images