1. A method for hiding a large field of view of laminated diffraction imaging is characterized by comprising the following steps:

constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

encoding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images;

loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator in sequence according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge-coupled device while loading each segmented visual key image;

scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

2. The method for hiding a large field of view in stacked diffraction imaging according to claim 1, wherein the scrambling the diffraction pattern to generate a scrambled hidden image specifically comprises:

using formulasScrambling the diffraction pattern to generate a scrambled hidden image; wherein, T is the hidden image after scrambling;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

3. A stacked diffraction imaging large field of view concealment system, comprising: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images;

the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image;

the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

4. The stacked diffraction imaging large field of view hiding system according to claim 3, wherein said scrambling module comprises:

a scrambling unit for using a formulaScrambling the diffraction pattern to generate a scrambled hidden image; wherein, T is the hidden image after scrambling;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

5. A large field of view extraction method for laminated diffraction imaging is characterized by comprising the following steps:

acquiring a scrambled hidden image; the hidden image is an image of a hidden visual key image;

extracting a diffraction pattern of the scrambled hidden image;

reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images;

and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

6. The method for extracting a large field of view for stacked diffraction imaging according to claim 5, wherein the extracting a diffraction pattern of the scrambled hidden image specifically comprises:

using formulasExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern; phi is a^-1Is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image.

7. A stacked diffraction imaging large field of view extraction system, comprising:

the hidden image acquisition module is used for acquiring the scrambled hidden image; the scrambled hidden image is an image of a hidden visual key image;

the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image;

the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images;

and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

8. The stacked diffraction imaging large-field-of-view extraction system according to claim 7, wherein the diffraction pattern extraction module specifically comprises:

a diffraction pattern extraction unit for using the formulaExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern; phi is a^-1Is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image.

9. A large-field-of-view hidden extraction method for laminated diffraction imaging is characterized by comprising the following steps: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

encoding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images;

loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator in sequence according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge-coupled device while loading each segmented visual key image;

scrambling the diffraction pattern to generate a scrambled hidden image; the scrambled hidden image is an image hiding the original image;

extracting a diffraction pattern of the scrambled hidden image;

reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images;

and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

10. A stacked diffraction imaging large field of view hidden extraction system, comprising: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images;

the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image;

the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; the scrambled hidden image is an image hiding the original image;

the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image;

the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images;

and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

Background

Under the development of information explosion, people have higher and higher requirements on safe storage, safe transmission and safe processing of information, so that information safety becomes one of global major problems and is related to various aspects of politics, economy, military, life and the like. The digital information processing is slow in speed and low in efficiency due to the seriousness, and the ever-increasing information security requirements of people cannot be met.

As traditional digital information security research continues to progress, modern optical theory and technology are gradually being incorporated into it. In 1995 researchers first proposed a dual random phase encoded optical image encryption technique based on a 4f imaging system. Compared with other computer electronic means, the optical information encryption technology has the advantages of high parallelism and high processing and transmission speed, and has a rich key space improved by the change of various parameters such as phase, amplitude, wavelength, polarization attitude and the like in an optical system. With optical image encryption technology as a starting end, optical information security technology has been developed rapidly in the last thirty years. In 2007, the american optical society began to embody it in two sub-classification numbers (060.4785, 100.4998) in the optical classification and indexing table (OCIS), which means that optical information security has begun to be a completely independent research area.

In recent years, various encryption methods have been reported in the literature to protect information because the combination of information hiding and optics becomes significant and effective due to the natural physical properties of optical methods, matching and coupling of various parameters, and the design of optical systems. Most of known encryption hiding systems based on optical systems are different, most of them copy or transfer an experimental graph acquired by an experiment, and then perform computer operation to complete related encryption hiding, and cannot synchronize a Charge-coupled Device (CCD), so that real-time encoding and hiding cannot be performed; in addition, the laminated imaging technology needs to obtain a plurality of object pinhole diffraction patterns, which is a very tedious work, but a mechanical movement mode is adopted, so that the real-time performance cannot be realized at all.

Disclosure of Invention

The invention aims to provide a method and a system for extracting large-field hiding of laminated diffraction imaging, which aim to solve the problem of poor real-time performance caused by the fact that real-time hiding cannot be coded in real time.

In order to achieve the purpose, the invention provides the following scheme:

a large field of view hiding method for stacked diffraction imaging comprises the following steps:

constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

encoding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images;

loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator in sequence according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge-coupled device while loading each segmented visual key image;

scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

Optionally, the scrambling the diffraction pattern to generate a scrambled hidden image specifically includes:

using formulasScrambling the diffraction pattern to generate a scrambled hidden image; wherein T isA scrambled hidden image;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

A stacked diffraction imaged large field of view concealment system, comprising: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images;

the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image;

the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

Optionally, the scrambling module specifically includes:

a scrambling unit for using a formulaScrambling the diffraction pattern to generate a scrambled hidden image; wherein the content of the first and second substances,t is a hidden image after scrambling;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

A large-field-of-view extraction method for laminated diffraction imaging comprises the following steps:

acquiring a scrambled hidden image; the hidden image is an image of a hidden visual key image;

extracting a diffraction pattern of the scrambled hidden image;

reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images;

and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

Optionally, the extracting a diffraction pattern of the scrambled hidden image specifically includes:

using formulasExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern; phi is a^-1Is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image.

A stacked diffraction imaging large field of view extraction system, comprising:

the hidden image acquisition module is used for acquiring the scrambled hidden image; the scrambled hidden image is an image of a hidden visual key image;

the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image;

the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images;

and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

Optionally, the diffraction pattern extraction module specifically includes:

a diffraction pattern extraction unit for using the formulaExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern; phi is a^-1Is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m x n diffraction patterns areA diffraction pattern corresponding to the segmented visual key image, wherein m is the number of rows of pixel points in the diffraction pattern, and n is the number of columns of pixel points in the diffraction pattern; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image.

A large-field-of-view hidden extraction method for laminated diffraction imaging comprises the following steps: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

encoding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images;

loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator in sequence according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge-coupled device while loading each segmented visual key image;

scrambling the diffraction pattern to generate a scrambled hidden image; the scrambled hidden image is an image hiding the original image;

extracting a diffraction pattern of the scrambled hidden image;

reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images;

and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

A stacked diffraction imaged large field of view hidden extraction system, comprising: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device;

the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images;

the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image;

the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; the scrambled hidden image is an image hiding the original image;

the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image;

the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images;

and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

According to the specific embodiment provided by the invention, the invention discloses the following technical effects: the invention provides a large-view-field hiding and extracting method and system for laminated diffraction imaging, wherein a reflective laminated imaging system is built, a spatial light modulator and a charge coupled device are connected together, a plurality of divided visual key images are sequentially loaded to different pixel positions of the spatial light modulator, and the charge coupled device is utilized to acquire diffraction patterns corresponding to the divided visual key images while each divided visual key image is loaded, so that the synchronous work of the spatial light modulator and the charge coupled device is realized, and the real-time encoding and real-time hiding are realized; meanwhile, the whole process of the invention does not need mechanical movement, and the original image can be coded and hidden only by using a computer, thereby realizing the real-time property of coding and hiding.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

FIG. 1 is a flow chart of a method for extracting large field of view hiding in laminated diffraction imaging according to the present invention;

FIG. 2 is an optical diagram of a reflective stacked imaging system;

FIG. 3 is a graph of results of an information hiding experiment;

fig. 4 is a schematic diagram of a visual key image recovered at different wavelengths.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The invention aims to provide a method and a system for extracting large-view-field hiding of laminated diffraction imaging, which can realize real-time coding and real-time hiding.

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.

A large field of view hiding method for stacked diffraction imaging comprises the following steps: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device; encoding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images; loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator in sequence according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge-coupled device while loading each segmented visual key image; scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

The scrambling the diffraction pattern to generate a scrambled hidden image specifically includes: using formulasScrambling the diffraction pattern to generate a scrambled hidden image; wherein, T is the hidden image after scrambling;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

A large-field-of-view extraction method for laminated diffraction imaging comprises the following steps: acquiring a scrambled hidden image; the hidden image is an image of a hidden visual key image; extracting a diffraction pattern of the scrambled hidden image; reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images; and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

The extracting the diffraction pattern of the scrambled hidden image specifically includes: using formulasExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern;_φ ^-1is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image. In the practical application of the method, the material is,to obtain the diffraction pattern I_m,nAnd splitting the image into m x n diffraction patterns, wherein the m x n diffraction patterns are diffraction patterns corresponding to the split visual key image.

Fig. 1 is a flowchart of a method for extracting a large field of view hiding in stacked diffraction imaging provided by the present invention, and as shown in fig. 1, the method for extracting a large field of view hiding in stacked diffraction imaging includes:

step 101: constructing a reflective laminated imaging system; the reflective stacked imaging system includes a spatial light modulator and a charge coupled device.

Step 102: and coding the covering image and the original image to generate a plurality of visual key images, and dividing each visual key image into a plurality of divided visual key images.

Step 103: and sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging image, and acquiring a diffraction pattern corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image.

Step 104: scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

Step 105: and extracting a diffraction pattern of the scrambled hidden image.

Step 106: and reconstructing the diffraction pattern by using an extended stack imaging algorithm to generate a plurality of visual key images.

Step 107: and carrying out incoherent superposition on the plurality of visual key images to determine an original image.

In practical application, the invention is divided into two parts:

step 1: constructing a reflective stacked imaging system, which comprises a Spatial Light Modulator (SLM) for loading information and a Charge-coupled Device (CCD) for collecting data;

step 2: cutting 2 visual keys into 72 small pictures of the visual keys at a computer end;

and step 3: sequentially loading 72 visual keys to different pixel positions of a liquid crystal display of the SLM according to the sequence of laminated imaging image acquisition, and acquiring corresponding diffraction patterns I on the CCD when each image is loaded_1,1，I_1,2…I_m,n-1，I_m,nWhere m and n represent the number of rows and columns, respectively.

The diffraction pattern containing the information is hidden by a reflective stack imaging method.

The hiding process of the information is as follows:

and 4, step 4: scrambling the diffraction patterns in sequence to obtain an image to be transmitted;

the information extraction and reconstruction process comprises the following steps:

and 5: extracting a diffraction pattern:

wherein phi-¹Showing the sequence of the diffraction patterns (the sequence of CCD acquisitions in the mounting step 3 is numbered 1,2, … m n in order); the symbol phi denotesScrambling the diffraction patterns (scrambling the numbers of the diffraction patterns acquired by the CCD in the mounting step 3); phi is a^-1Showing the sequence of the diffraction patterns (the sequence of CCD acquisitions in the mounting step 3 is numbered 1,2, … m n in order);andrepresenting the compression and recovery of the diffraction spot;representing a large image I with m x n compressed diffraction patterns arranged in m rows and n columns_m,n；Represents that_m,nSplitting into m x n individual diffractograms; alpha is an attenuation factor; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image; t is a hidden image after scrambling; namely: and sequentially scrambling, compressing, combining and hiding the diffraction pattern in the host image to obtain the image to be transmitted.

Step 6: after the diffraction pattern is obtained, it is reconstructed by recovery. The diffraction pattern I obtained here is the extended Ptycholographic Iterative Engine (ePIE) pair in the Ptycholographic imaging_m,nCarrying out reconstruction;

and 7: and after the reconstruction is recovered, a visual key hidden by the laminated imaging system can be obtained, and the two visual keys are subjected to incoherent superposition to obtain secret information.

The technical solution of the present invention is described below in terms of a specific experimental procedure.

Fig. 2 is a light path diagram of a reflective stacked imaging system, in fig. 2, Laser is a Laser, CVF is an attenuator, Mirror is a reflector, AT is a polarizer, Filter is a beam expander, PBS is a polarization splitting prism, Lens is a Lens, Pinhole1 is a diaphragm, BS is a splitting prism, CCD is a charge-coupled device, SLM is a spatial light modulator, and PC is a calculator. The specific experimental parameters were as follows: laser, gas Laser wavelength 632.8nm, red, Mirror, AT: polarizing plate, fitter: spatial filter, Lens: collimating lens, Pinhole 1: small-pore probe, BS: beam splitter prism, PBS: polarizing beam splitter, SLM: reflective spatial light modulator, Holoeye reflective pure phase spatial light modulator (PLUTO-VIS-016-SLM), CCD: the CCD (model IGV-B4020M-KF000) pixel size of IMPERX is 9um, and the actual usage wavefront size is 1024X1024 pix. With the scanning mode of 6X6, the fault tolerance of the visual password is about 7% at the lowest. Diffraction distance Z182 mm, PC: and a computer connected with the CCD and the SLM.

The laser beam is adjusted into a beam of parallel light after passing through the reflector, the single light spot is very small, so the beam is shaped into a beam of plane wave after passing through the spatial filter and the collimating lens, the beam is relatively large, the attenuator is used for adjusting the laser intensity to meet the requirement of subsequent experiments, the PBS is used for meeting the pure phase modulation requirement of the SLM, the laser beam passes through the probe small hole through the polarizer, the irradiated reflective spatial light modulator is reflected by the BS to enter the CCD, and finally the CCD receives a diffraction pattern and transmits the diffraction pattern to the PC computer.

Description of the experimental procedures of the optical path:

(1) no mechanical movement exists in the light path, no matter a moving object or a moving small-hole probe is selected, in the experiment, the invention does not need to move any instrument, and the relative displacement can be obtained by using a computer.

(2) Reflective spatial light modulators are used because the diffraction patterns collected in experiments in particular real life are almost reflective, at least transmissive, and because the human eye is imaging in reflection.

(3) The invention realizes the synchronous work of the CCD and the SLM after connecting the CCD and the SLM together, which realizes the real-time property provided by the invention, certainly not only is limited to a visual key, no matter what image information needs to be hidden is replaced, the invention can carry out real-time coding and then hiding, which is different from most known encryption hiding systems, most of the CCD encryption hiding systems copy or transfer experimental graphs acquired by experiments, then carry out the operation of a computer to complete the related encryption hiding, and cannot synchronize the CCD.

(4) The laminated imaging technology needs to obtain a plurality of object pinhole diffraction patterns, which is a very tedious work, however, the real-time performance cannot be realized at all by adopting a mechanical movement mode, so that the system has no mechanical movement and has the advantage of real-time performance.

Fig. 3 is a diagram showing the result of an information hiding experiment, and as shown in fig. 3, a masking image and secret information (original image) are first selected, and then an Enhanced Visual Cryptography (EVC) is used to obtain two pieces of shared information (visual key image). Respectively cutting the two visual keys into 6 × 6 small graphs, loading 72 small graphs of the visual keys to an area array area on the SLM, collecting 72 diffraction graphs in total, respectively arranging the diffraction graphs of the two visual keys in sequence, recovering the two visual keys by using an ePIE algorithm, and finally performing incoherent superposition on the recovered two visual keys to obtain secret information.

Fig. 4 is a schematic diagram of the visual key image recovered by different wavelengths, and it is apparent from fig. 4 that the best recovery is achieved when the wavelength lambda is 632.8nm, and the best effect can be decoded when the data is consistent with that used in the experiment. The invention can provide the support that the shape, the size, the sequence, the position, the wavelength, the diffraction distance and the like of the probe can provide safety for the system. In practical application, the specific content of the visual key cannot be seen by randomly changing the sequence of 6 diffraction patterns, so that the enhanced visual password and the large-field-of-view hiding method of the laminated diffraction imaging can be seen, and the method has feasibility and high safety.

In addition, the invention also discloses a large-view-field hiding system for laminated diffraction imaging, which comprises: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device; the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images; the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image; the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; and the scrambled hidden image is an image hiding the original image.

The scrambling module specifically comprises: a scrambling unit for using a formulaScrambling the diffraction pattern to generate a scrambled hidden image; wherein, T is the hidden image after scrambling;to compress the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; phi (I)_m,n) Scrambling process of diffraction pattern of m rows and n columns; alpha is an attenuation factor; h is a host image.

A stacked diffraction imaging large field of view extraction system, comprising: the hidden image acquisition module is used for acquiring the scrambled hidden image; the scrambled hidden image is an image of a hidden visual key image; the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image; the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images; and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

The diffraction pattern extraction module specifically comprises: diffraction patternAn extraction unit for utilizing the formulaExtracting a diffraction pattern of the scrambled hidden image; wherein, I_m,nThe diffraction pattern is a diffraction pattern with m rows and n columns, wherein m is the row number of pixel points in the diffraction pattern, and n is the column number of the pixel points in the diffraction pattern; phi is a^-1Is a diffraction pattern I_m,nThe sorting process of (1);to reduce the diffraction spots of the diffraction pattern;arranging the compressed m x n diffraction patterns into a diffraction pattern I with m rows and n columns_m,nThe m-n diffraction patterns are diffraction patterns corresponding to the segmented visual key image, m is the number of rows of pixel points in the diffraction patterns, and n is the number of columns of pixel points in the diffraction patterns; t is a hidden image after scrambling; alpha is alpha^-1To the negative 1 power of the attenuation factor; h is a host image.

A stacked diffraction imaged large field of view hidden extraction system, comprising: constructing a reflective laminated imaging system; the reflective stacked imaging system comprises a spatial light modulator and a charge coupled device; the visual key image segmentation module is used for encoding the covering image and the original image to generate a plurality of visual key images and segmenting each visual key image into a plurality of segmented visual key images; the diffraction pattern determining module is used for sequentially loading a plurality of the segmented visual key images to different pixel positions of the spatial light modulator according to the acquisition sequence of the laminated imaging images, and acquiring diffraction patterns corresponding to the segmented visual key images by using the charge coupled device while loading each segmented visual key image; the scrambling module is used for scrambling the diffraction pattern to generate a scrambled hidden image; the scrambled hidden image is an image hiding the original image; the diffraction pattern extraction module is used for extracting the diffraction pattern of the scrambled hidden image; the visual key image generation module is used for reconstructing the diffraction pattern by using an extended laminated imaging algorithm to generate a plurality of visual key images; and the original image determining module is used for carrying out incoherent superposition on the plurality of visual key images to determine an original image.

The invention provides a method for extracting information by applying non-mechanical mobile overlay (NPE) imaging after a masked image and a secret image are subjected to an Enhanced Visual Cryptography (EVC) scheme. Because the laminated diffraction imaging technology has the advantages of large field of view, good imaging quality and the like. Therefore, the enhanced visual password is combined with non-mechanical movable type laminated optical image hiding, the problem that large visual field information is difficult to coherently superpose can be solved, and the security is high.

In the invention, the implementation process is as follows: 1) first, a masking image and secret information are selected, and two shared images VK1 and VK2 are obtained by using enhanced visual cryptography.

2) The two shared images VK1 and VK2 were cut into 6 × 6 pictures, for a total of 72.

3) And loading 72 pieces of information to the spatial light modulator through a non-mechanical laminated imaging light path by using a reflective coherent diffraction imaging system, acquiring corresponding diffraction images on the charge coupled device while loading 72 pieces of information until all diffraction patterns corresponding to 72 pieces of information are acquired, and storing the diffraction patterns in a diffraction database after the optical system is encoded.

4) The diffraction patterns in the diffraction database are ranked in order.

5) When information is extracted, the epie algorithm is used for recovering the ordered diffraction patterns, and meanwhile, parameters such as diffraction distance, moving distance and the like are required to be known, so that secret information can be accurately and completely extracted.

6) The safety of the scheme is tested, namely scrambling codes and aspects of wavelength, pixel size, diffraction distance and the like.

Therefore, the invention can achieve the following effects:

1) safety: the laminated diffraction imaging technology needs matching and coupling of various parameters, such as scrambling codes, wavelengths, pixel sizes, diffraction distances and other parameters, and ensures the safety of the system.

2) Large capacity: the combination of enhanced visual cryptography and stacked diffraction imaging solves the problem of incoherent superposition of large-field pictures.

3) And (3) timeliness: and simultaneously controlling the CCD and the SLM by using a computer (PC), wherein the frame rates of the CCD and the SLM are 1/60(s), namely, 60 visual keys can be adopted as corresponding diffraction patterns at most every second, and certain timeliness is achieved.

4) Stability: once the optical system is completely built, other changes are not needed, and information hiding and extraction can be quickly finished on a PC.

The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.

The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.