Watermark steganography, identification method and system of education examination image

Abstract

The embodiment of the present application relates to the technical field of image processing, and specifically discloses an education examination image watermark steganography, identification method and system, comprising: obtaining an examinee image and examination information to be added with a watermark, performing Fourier transform on the examinee image to obtain a frequency spectrum diagram of the examinee image, generating a watermark image by using the examination information, and performing Fourier transform on the watermark image to obtain a frequency spectrum diagram of the watermark image, fusing the frequency spectrum diagram of the examinee image and the frequency spectrum diagram of the watermark image to obtain a frequency spectrum diagram after writing the watermark, and performing inverse Fourier transform on the frequency spectrum diagram after writing the watermark to obtain an examinee image after steganography watermarking. The watermark is written in the frequency domain of the examinee image, on the one hand, the watermark steganography is realized in the examinee image, and it is difficult to be destroyed, thereby providing a reliable basis for the authenticity and traceability of the examinee image, on the other hand, various formats of images can be converted into frequency spectrum diagrams, and the watermark steganography is suitable for various formats of examinee images.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of image processing, and particularly relates to a watermark steganography, recognition method and system for education examination images. BACKGROUND

[0002] In online education examinations, examinee images are used to verify the identities of examinees, and examinee image acquisition is an important link in online transaction examinations. In order to realize the authenticity and traceability of examinee images, it is necessary to add a watermark to the examinee images.

[0003] In the prior art, a digital watermark is mainly added to the spatial domain or the head and tail of an examinee image, or the digital watermark is added to the background of the examinee image in the same color as the background of the examinee image. The embedded digital watermark is easily damaged in the forwarding process of the examinee image, and the existing digital watermark steganography technology is mainly for PNG format images, but the size of the PNG format examinee image in online education examinations is larger than the size requirement of the online examination industry, and the online transaction examination mainly uses a JPG format examinee image. SUMMARY

[0004] The purpose of the embodiments of the present application is to provide a watermark steganography, recognition method and system for education examination images, aiming to solve the problems that the current writing of a digital watermark in the spatial domain or the background of an examinee image is easily damaged and not applicable to a JPG format examinee image.

[0005] To achieve the above-mentioned purpose, the embodiments of the present application provide the following technical solutions:

[0006] A watermark steganography method for education examination images, specifically comprising the following steps:

[0007] Obtaining an examinee image to which a watermark is to be added and examination information;

[0008] Performing Fourier transform on the examinee image to obtain a frequency spectrum of the examinee image;

[0009] Generating a watermark image using the examination information, and performing Fourier transform on the watermark image to obtain a frequency spectrum of the watermark image;

[0010] Fusing the frequency spectrum of the examinee image and the frequency spectrum of the watermark image to obtain a frequency spectrum after writing a watermark;

[0011] Performing inverse Fourier transform on the frequency spectrum after writing the watermark to obtain an examinee image after steganography of the watermark.

[0012] As a further limitation of the technical solutions of the embodiments of the present application, the obtaining of the examinee image to which the watermark is to be added and the examination information specifically comprises the following steps:

[0013] Collecting an image in JPG format of the examinee as an examinee image to be added with a watermark;

[0014] Obtaining examinee information of the examinee, the examinee information including at least one of a test number, an examinee name and examinee identity information, and obtaining collection information of the examinee image, the collection information including at least one of an examinee type, an image collection mode and an image collection platform;

[0015] Encoding the examinee information and the collection information into test information.

[0016] As a further limitation of the technical scheme of the embodiment of the present application, Fourier transform is performed on the examinee image to obtain a frequency spectrum graph of the examinee image, specifically including the following steps:

[0017] Performing Fourier transform on the examinee image to obtain a first frequency spectrum graph of the examinee image;

[0018] Performing filtering processing on the first frequency spectrum graph through a noise filter to obtain a second frequency spectrum graph after filtering, as an image content frequency spectrum graph of the examinee image;

[0019] Performing difference processing on the first frequency spectrum graph and the second frequency spectrum graph to obtain a third frequency spectrum graph, as a noise frequency spectrum graph of the examinee image.

[0020] As a further limitation of the technical scheme of the embodiment of the present application, a watermark image is generated using the test information, and Fourier transform is performed on the watermark image to obtain a frequency spectrum graph of the watermark image, specifically including the following steps:

[0021] Performing encryption processing on the test information to obtain ciphertext;

[0022] Writing the ciphertext into a preset watermark image template to obtain a watermark image;

[0023] Performing Fourier transform on the watermark image to obtain a frequency spectrum graph of the watermark image.

[0024] As a further limitation of the technical scheme of the embodiment of the present application, the frequency spectrum graph of the examinee image and the frequency spectrum graph of the watermark are fused to obtain a frequency spectrum graph after writing the watermark, specifically including the following steps:

[0025] Fusing the noise frequency spectrum graph of the examinee image and the frequency spectrum graph of the watermark image to obtain a fused noise frequency spectrum graph;

[0026] Fusing the fused noise frequency spectrum graph and the image content frequency spectrum graph of the examinee image to obtain a frequency spectrum graph after writing the watermark.

[0027] A watermark identification method for an education examination image, specifically including the following steps:

[0028] obtaining a reference image to be identified, the reference image being an image with a watermark hidden by the watermark steganography method of the educational examination image according to any one of claims 1-5;

[0029] performing Fourier transform on the reference image to obtain a frequency spectrum of the reference image;

[0030] separating a watermark frequency spectrum from the frequency spectrum;

[0031] performing inverse Fourier transform on the watermark frequency spectrum to obtain a watermark image;

[0032] identifying authenticity of the reference image based on the watermark image.

[0033] As a further limitation of the technical scheme of the embodiment of the present application, the step of identifying authenticity of the reference image based on the watermark image specifically comprises the following steps:

[0034] extracting examination information from the watermark image;

[0035] when the examination information is ciphertext, decrypting the ciphertext by using a preset encryption algorithm to obtain plaintext examination information, the examination information comprising examinee information and acquisition information of the reference image, the examinee information comprising at least one of examination number, examinee name, and examinee identity information, the acquisition information comprising at least one of examinee type, image acquisition method, and image acquisition platform;

[0036] when the examinee information matches preset examinee information and the acquisition information matches preset acquisition information, determining that the reference image is a real image;

[0037] when the examinee information does not match preset examinee information and / or the acquisition information does not match preset acquisition information, determining that the reference image is a counterfeit image.

[0038] As a further limitation of the technical scheme of the embodiment of the present application, after identifying authenticity of the reference image based on the watermark image, the method specifically further comprises the following steps:

[0039] when the reference image is a real image, acquiring an image of an examinee to be verified to obtain a to-be-verified image;

[0040] performing identity verification on the examinee to be verified by using the reference image and the to-be-verified image.

[0041] A watermark steganography system for educational examination images, specifically comprising the following units:

[0042] An image and examination information acquisition unit is configured to acquire an examinee image and examination information to be added with a watermark;

[0043] An examinee image frequency domain conversion unit is configured to perform Fourier transform on the examinee image to obtain a frequency spectrum of the examinee image;

[0044] A watermark frequency domain conversion unit is configured to generate a watermark image by using the examination information, and perform Fourier transform on the watermark image to obtain a frequency spectrum of the watermark image;

[0045] A watermark writing unit is configured to fuse the frequency spectrum of the examinee image and the frequency spectrum of the watermark image to obtain a frequency spectrum after watermark writing;

[0046] An inverse Fourier transform unit is configured to perform inverse Fourier transform on the frequency spectrum after watermark writing to obtain an examinee image after steganographic watermarking.

[0047] A watermark identification system for an education examination image, specifically comprising the following units:

[0048] A to-be-identified image acquisition unit is configured to acquire a reference image to be identified, the reference image being an image after steganographic watermarking by the education examination image steganographic watermarking method of any of the embodiments of the present application;

[0049] An image frequency domain conversion unit is configured to perform Fourier transform on the reference image to obtain a frequency spectrum of the reference image;

[0050] A watermark frequency spectrum separation unit is configured to separate a watermark frequency spectrum from the frequency spectrum;

[0051] A watermark frequency spectrum time domain conversion unit is configured to perform inverse Fourier transform on the watermark frequency spectrum to obtain a watermark image;

[0052] A reference image authenticity identification unit is configured to identify authenticity of the reference image based on the watermark image.

[0053] Compared with the prior art, the present application has the following beneficial effects:

[0054] The embodiment of the present application obtains the examinee image and the examination information after adding the watermark, and performs Fourier transform on the examinee image to obtain the frequency spectrum of the examinee image, generates a watermark image by using the examination information, and performs Fourier transform on the watermark image to obtain the frequency spectrum of the watermark image, fuses the frequency spectrum of the examinee image and the frequency spectrum of the watermark to obtain the frequency spectrum after writing the watermark, and performs inverse Fourier transform on the frequency spectrum after writing the watermark to obtain the examinee image after steganography, realizes writing the watermark in the frequency domain of the examinee image, on the one hand, realizes steganography of the watermark in the examinee image, and is difficult to destroy, provides reliable basis for the authenticity and traceability of the examinee image, on the other hand, various formats of images can be converted into frequency spectrum, and the steganography of the watermark is suitable for various formats of examinee images. BRIEF DESCRIPTION OF DRAWINGS

[0055] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application.

[0056] Figure 1 A flow chart of the watermark steganography method of the education examination image provided by an embodiment of the present application is shown.

[0057] Figure 2 A flow chart of the watermark steganography method of the education examination image provided by an embodiment of the present application is shown.

[0058] Figure 3 A flow chart of the watermark steganography method of the education examination image provided by an embodiment of the present application is shown.

[0059] Figure 4 An application architecture diagram of the watermark steganography system of the education examination image provided by an embodiment of the present application is shown.

[0060] Figure 5 An application architecture diagram of the watermark steganography system of the education examination image provided by an embodiment of the present application is shown. DETAILED DESCRIPTION

[0061] In order to make the objects, technical solutions and advantages of the present application more clear, the following will further describe the present application in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application, and are not used to limit the present application.

[0062] Figure 1 A flow chart of the watermark steganography method of the education examination image provided by an embodiment of the present application is shown. Specifically, the watermark steganography method of the education examination image of the embodiment of the present application specifically includes the following steps:

[0063] Step S101, obtaining the examinee image and the examination information to be added with the watermark.

[0064] The embodiment can be applied to a scene where the online examination system adds examination information in the form of a watermark to the collected examinee image when collecting the examinee image, specifically, the online examination system can add a watermark to the collected image of the registered examinee when the examinee registers, of course, it can also be applied to a scene where the online examination system collects the examinee image in real time and adds examination information in the form of a watermark to the collected examinee image, wherein the examinee image of the embodiment can be an image processed in compliance with regulations, such as partially covering the private information of the examinee, such as a mobile phone number and an ID number.

[0065] In one embodiment, the examinee image in JPG format can be collected as the examinee image to which the watermark is to be added, the examinee information of the examinee and the collection information of the examinee image are obtained, and the examinee information and the collection information are encoded as examination information, wherein the examinee information can include at least one of an examination number (such as an admission ticket number), an examinee name, and examinee identity information (such as an ID number), the collection information can include at least one of an examinee type, an image collection method, and an image collection platform, and an exemplary examination information encoding template can be set, such as an order encoding of the examinee information in front and the collection information behind, wherein the encoding can mean digitizing the examinee information and the collection information, such as using specific characters to replace the examination type, the image collection method, and the image collection platform. The examinee information such as the examination number, the examinee name, and the examinee identity information can be used for examinee identity verification, and the examinee type, the image collection method, and the image collection platform can be used to trace whether the source of the examinee image is legal.

[0066] In step S102, the Fourier transform is performed on the examinee image to obtain a frequency spectrum of the examinee image.

[0067] In the embodiment, the Fourier transform can be a discrete Fourier transform (DFT), which can transform a signal from a time domain to a frequency domain, and analyze and process the signal in the frequency domain. Discrete Fourier transform of the image can be converting the image from a spatial domain to a frequency domain to obtain a frequency spectrum, in which low frequency represents gradual change (such as gray scale gradual change) in the image, contains the most information, low frequency determines the overall shape or pattern in the image, and represents the image content, high frequency corresponds to sudden change in the image, provides more details in the image, and also contains more noise.

[0068] Specific to the embodiment, the examinee image can be subjected to Fourier transform to obtain a first frequency spectrum of the examinee image, and the first frequency spectrum can be further subjected to filtering processing by a noise filter to obtain a second frequency spectrum after filtering, so as to serve as an image content frequency spectrum of the examinee image. A third frequency spectrum can be obtained by difference processing of the first frequency spectrum and the second frequency spectrum, so as to serve as a noise frequency spectrum of the examinee image. The noise filter can be a low-pass filter, so that the second frequency spectrum is a frequency spectrum lower than a threshold frequency, so as to retain the examinee image content. The first frequency can be set according to actual conditions, for example, the threshold frequency can be set according to the performance of a camera or a camera in the online examination system. The third frequency spectrum obtained by difference operation of the first frequency spectrum and the second frequency spectrum is a frequency spectrum of noise filtered by the low-pass filter, that is, after Fourier transform of the examinee image, the image content frequency spectrum retaining the examinee image content and the noise frequency spectrum of the noise in the examinee image are obtained.

[0069] In step S103, a watermark image is generated by using the examination information, and a frequency spectrum of the watermark image is obtained by Fourier transform of the watermark image.

[0070] Specifically, the examination information can be subjected to encryption processing to obtain ciphertext, the ciphertext can be written into a preset watermark image template to obtain the watermark image, and the watermark image can be subjected to Fourier transform to obtain a frequency spectrum of the watermark image.

[0071] In one embodiment, the examination information can be subjected to encryption by using AES (Advanced Encryption Standard) to obtain ciphertext.

[0072] In another embodiment, a plurality of ciphertext embedding positions randomly distributed in the watermark image template can be set in the watermark image template, each ciphertext embedding position is provided with a position serial number. After the examination information is subjected to encryption to obtain ciphertext, the ciphertext can be segmented to obtain a plurality of ciphertext segments and ciphertext segment serial numbers. The number of the ciphertext segments is the same as the number of the ciphertext embedding positions. The ciphertext segments are embedded into the ciphertext embedding positions in the watermark image template in a one-to-one correspondence manner of the ciphertext segment serial numbers and the position serial numbers, to obtain the watermark image. The watermark image can be further subjected to Fourier transform to obtain a frequency spectrum of the watermark image.

[0073] In step S104, the frequency spectrum of the examinee image and the frequency spectrum of the watermark image are fused to obtain a frequency spectrum after watermark writing.

[0074] In one embodiment, after Fourier transform of the examinee image to obtain the image content spectrum graph and noise spectrum graph of the examinee image, and Fourier transform of the watermark image to obtain the spectrum graph of the watermark image, the noise spectrum graph of the examinee image and the spectrum graph of the watermark image can be fused to obtain a fused noise spectrum graph, and the fused noise spectrum graph and the image content spectrum graph of the examinee image are fused to obtain the spectrum graph after watermark writing, wherein the spectrum graph fusion can be spectrum graph addition, multiplication, weighted average, wavelet transform, convolution, etc., and the embodiment does not limit the way of spectrum graph fusion.

[0075] Step S105, inverse Fourier transform of the spectrum graph after watermark writing to obtain the steganographic watermarking examinee image.

[0076] Inverse Fourier transform can convert frequency domain signals into time domain signals. For images, inverse Fourier transform can convert the spectrum graph after watermark writing into an examinee image in the spatial domain, which includes an invisible watermark image.

[0077] Figure 2 The figure shows a schematic diagram of steganographic watermarking in the examinee image, in which Figure 2 After obtaining the examinee image after compliance processing, Fourier transform of the examinee image is performed to obtain the image content and noise content in the frequency domain, the encrypted watermark image is Fourier transformed and fused with the noise content to obtain the fused noise content, and the noise content and the image content are further fused to obtain the frequency domain data after the watermark and the image content are fused. After inverse Fourier transform of the frequency domain data, the steganographic watermarking examinee image is obtained.

[0078] After obtaining the examinee image to be added with a watermark and the examination information, the examinee image is Fourier transformed to obtain the spectrum graph of the examinee image, the watermark image is generated using the examination information, and the watermark image is Fourier transformed to obtain the spectrum graph of the watermark image. The spectrum graph of the examinee image and the spectrum graph of the watermark are fused to obtain the spectrum graph after steganographic watermarking, and the spectrum graph after watermark writing is inverse Fourier transformed to obtain the steganographic watermarking examinee image, which realizes watermark writing in the frequency domain of the examinee image. On the one hand, the watermark is steganographically written in the examinee image and is difficult to destroy, providing a reliable basis for the authenticity and traceability of the examinee image. On the other hand, various formats of images can be converted into spectrum graphs, which are suitable for steganographic watermarking of various formats of examinee images.

[0079] Further, after the Fourier transform of the examinee image is performed to obtain the frequency spectrum of the examinee image, low-pass filtering processing is performed to obtain a noise frequency spectrum, the noise frequency spectrum is fused with the frequency spectrum of the watermark image, and then the fusion result is fused with the image content frequency spectrum of the examinee image, and after inverse Fourier transform, the examinee image after steganography watermarking is obtained, so that the watermark is written into the noise frequency spectrum of the examinee image, and the written watermark exists in the examinee image in the form of noise, without affecting the content of the examinee image.

[0080] Further, the examination information is encrypted first, and then a watermark image in the form of ciphertext is generated and steganographically written into the examinee image, so that the security of the information of the examinee image is improved.

[0081] Figure 3 A flowchart of the watermark identification method of the education examination image provided by the embodiment of the present application is shown. Specifically, the watermark identification method of the education examination image of the embodiment of the present application specifically includes the following steps:

[0082] In step S201, a reference image to be identified is obtained.

[0083] The reference image to be identified of the embodiment of the present application can be a steganographically watermarked image generated by the watermark steganography method of the education examination image of the embodiment of the present application. The reference image to be identified can be an image pre-recorded in an online education examination system. For example, when the identity of an examinee needs to be verified in an online examination, after the image of the examinee to be verified is collected, the pre-recorded reference image of the examinee is obtained from the system, and the collected image is matched with the reference image to verify the identity of the examinee.

[0084] In one example, the corresponding reference image can be obtained from the examination system by using the examination number, identity information and the like provided by the examinee to be verified when the examinee enters the examination system, so as to serve as the reference image to be identified.

[0085] In another example, after the examinee logs in to the examination system during the examination, the corresponding reference image can be found from the examination system by using the examination number, identity card and the like used by the examinee when the examinee logs in, so as to serve as the reference image to be identified.

[0086] In step S202, the Fourier transform of the reference image is performed to obtain the frequency spectrum of the reference image.

[0087] In the embodiment, the discrete Fourier transform can be used to process the reference image, so that the reference image is transformed from a spatial domain image to a frequency domain image, and the frequency spectrum of the reference image is obtained.

[0088] In step S203, the frequency spectrum of the watermark is separated from the frequency spectrum.

[0089] In this embodiment, the watermark is written into the reference image in the form of noise, and the frequency spectrum of the reference image can be filtered to obtain the image content frequency spectrum and the noise frequency spectrum of the reference image. For example, the frequency spectrum of the reference image can be filtered by a low-pass filter, wherein the threshold frequency of the low-pass filter can be set according to the performance of the camera or the camera used to collect the image and pre-stored in the system. The noise frequency spectrum can include the original noise in the reference image and the frequency spectrum of the watermark. Since the original noise in the reference image does not affect the content of the watermark, the noise frequency spectrum separated from the frequency spectrum of the reference image can be directly used as the frequency spectrum of the watermark.

[0090] In step S204, inverse Fourier transform is performed on the frequency spectrum of the watermark to obtain a watermark image.

[0091] After obtaining the frequency spectrum of the watermark image, inverse Fourier transform can be performed on the frequency spectrum of the watermark to obtain a watermark image.

[0092] In step S205, the authenticity of the examinee image is identified based on the watermark image.

[0093] In one embodiment, the examination information can be extracted from the watermark image. When the examination information is ciphertext, a preset encryption algorithm is used to decrypt the ciphertext to obtain plaintext examination information. The examination information includes examinee information and image collection information of the examinee image. The examinee information includes at least one of the examination number, the examinee's name, and the examinee's identity information. The collection information includes at least one of the examinee type, the image collection method, and the image collection platform. When the examinee information matches the preset examinee information and the collection information matches the preset collection information, the examinee image is determined to be a real image. When the examinee information does not match the preset examinee information and / or the collection information does not match the preset collection information, the examinee image is determined to be a counterfeit image.

[0094] In one embodiment, a plurality of ciphertext embedding positions are set in the watermark image, each ciphertext embedding position is provided with a position serial number, and the ciphertexts can be extracted from the watermark image according to the position serial numbers and spliced to obtain spliced ciphertext examination information. The spliced ciphertext can be decrypted by the corresponding decryption algorithm of the encryption algorithm to obtain plaintext examination information. The decryption algorithm can be pre-configured in the system.

[0095] If the examination information matches the preset examination information, the reference image is determined to be a real image collected by a legal channel and conforming to the content specifications of the education examination system. Otherwise, it is a counterfeit image. The image collection method and the image collection platform in the decrypted collection information can be traced back, thereby ensuring the legality and effectiveness of the reference image.

[0096] After determining that the reference image is a real and legal image, an image of an examinee to be verified can be collected to obtain a to-be-verified image, and the to-be-verified image and the reference image are used to verify the identity of the examinee to be verified. Specifically, the image of the examinee can be collected by a camera when the examinee logs in to an education examinee system, or the image of the examinee can be collected during the examination as the to-be-verified image. The to-be-verified image and the reference image are matched. If the matching is passed, it is determined that the identity verification of the examinee is passed. Otherwise, it is determined that the identity verification of the examinee is not passed. An alarm information can be generated to avoid the phenomenon of proxy examination.

[0097] The reference image to be recognized in the embodiment has a watermark hidden therein. A frequency spectrum graph of the reference image is obtained by performing Fourier transform on the reference image. A frequency spectrum graph of the watermark is separated from the frequency spectrum graph. The watermark image is obtained by performing inverse Fourier transform on the frequency spectrum graph of the watermark. The authenticity of the examinee image is identified based on the watermark image. Since the watermark is hidden in the reference image by Fourier transform, on the one hand, the watermark is hidden in the reference image and is difficult to be destroyed, thereby providing a reliable basis for the authenticity and traceability of the reference image. On the other hand, images of various formats can be converted into frequency spectrum graphs, and the watermark can be hidden in reference images of various formats. When the authenticity of the reference image is identified, the watermark image can be obtained by Fourier transform and inverse transform, and then the authenticity is verified.

[0098] Figure 4 An application architecture diagram of the watermark hiding system for the education examination image provided by the embodiment of the present application is shown. The watermark hiding system for the education examination image of the embodiment should specifically include the following units:

[0099] An image and examination information acquisition unit 401 is configured to acquire an examinee image to which a watermark is to be added and examination information.

[0100] An examinee image frequency domain conversion unit 402 is configured to perform Fourier transform on the examinee image to obtain a frequency spectrum graph of the examinee image.

[0101] A watermark frequency domain conversion unit 403 is configured to generate a watermark image by using the examination information, and perform Fourier transform on the watermark image to obtain a frequency spectrum graph of the watermark image.

[0102] A watermark writing unit 404 is configured to fuse the frequency spectrum graph of the examinee image and the frequency spectrum graph of the watermark image to obtain a frequency spectrum graph after the watermark is written.

[0103] An inverse Fourier transform unit 405 is configured to perform inverse Fourier transform on the frequency spectrum graph after the watermark is written to obtain an examinee image after the watermark is hidden.

[0104] As a further limitation of the technical scheme of the embodiment of the present application, the image and examination information acquisition unit 401 specifically includes the following modules:

[0105] The examinee image acquisition module is configured to acquire an examinee image in JPG format as an examinee image to which a watermark is to be added.

[0106] The examinee information and acquisition information acquisition module is configured to acquire examinee information of the examinee and acquisition information of the examinee image, wherein the examinee information comprises at least one of a test number, an examinee name and examinee identity information, and the acquisition information comprises at least one of an examinee type, an image acquisition mode and an image acquisition platform.

[0107] The test information determination module is configured to encode the examinee information and the acquisition information into test information.

[0108] As a further limitation of the technical scheme of the embodiment of the present application, the examinee image frequency domain conversion unit 402 specifically comprises the following modules:

[0109] The examinee image frequency domain conversion module is configured to perform Fourier transform on the examinee image to obtain a first frequency spectrum graph of the examinee image.

[0110] The image content frequency spectrum graph acquisition module is configured to filter the first frequency spectrum graph through a noise filter to obtain a second frequency spectrum graph after filtering, as an image content frequency spectrum graph of the examinee image.

[0111] The noise frequency spectrum graph acquisition module is configured to perform difference processing on the first frequency spectrum graph and the second frequency spectrum graph to obtain a third frequency spectrum graph, as a noise frequency spectrum graph of the examinee image.

[0112] As a further limitation of the technical scheme of the embodiment of the present application, the watermark frequency domain conversion unit 403 comprises the following modules:

[0113] The encryption module is configured to perform encryption processing on the test information to obtain ciphertext.

[0114] The watermark image generation module is configured to write the ciphertext into a preset watermark image template to obtain a watermark image.

[0115] The watermark frequency domain conversion module is configured to perform Fourier transform on the watermark image to obtain a frequency spectrum graph of the watermark image.

[0116] As a further limitation of the technical scheme of the embodiment of the present application, the watermark writing unit 404 specifically comprises the following modules:

[0117] The noise and watermark fusion module is configured to fuse the noise frequency spectrum graph of the examinee image and the frequency spectrum graph of the watermark image to obtain a fused noise frequency spectrum graph.

[0118] The noise and examinee image content fusion module is configured to fuse the fused noise frequency spectrum graph and the image content frequency spectrum graph of the examinee image to obtain a frequency spectrum graph after writing the watermark.

[0119] Figure 5 An application architecture diagram of the watermark identification system of the education examination image provided by the embodiment of the present application is shown. The watermark identification system of the education examination image of the embodiment should specifically include the following units:

[0120] The to-be-identified image acquisition unit 501 is configured to acquire a reference image to be identified, wherein the reference image is an image with watermark written by the watermark steganography method of the education examination image of any of the embodiments of the present application.

[0121] The image frequency domain conversion unit 502 is configured to perform Fourier transform on the reference image to obtain a frequency spectrum diagram of the reference image.

[0122] The watermark frequency spectrum diagram separation unit 503 is configured to separate a watermark frequency spectrum diagram from the frequency spectrum diagram.

[0123] The watermark frequency spectrum diagram time domain conversion unit 504 is configured to perform inverse Fourier transform on the watermark frequency spectrum diagram to obtain a watermark image.

[0124] The reference image authenticity identification unit 505 is configured to identify the authenticity of the reference image based on the watermark image.

[0125] As a further limitation of the technical scheme of the embodiment of the present application, the reference image authenticity identification unit 505 specifically includes the following modules:

[0126] The examination information extraction module is configured to extract examination information from the watermark image.

[0127] The examination information decryption module is configured to, when the examination information is ciphertext, decrypt the ciphertext by using a preset encryption algorithm to obtain plaintext examination information. The examination information includes examinee information and collection information of the examinee image. The examinee information includes at least one of an examination number, an examinee name, and examinee identity information. The collection information includes at least one of an examinee type, an image collection method, and an image collection platform.

[0128] The real image determination module is configured to determine that the examinee image is a real image when the examinee information matches preset examinee information and the collection information matches preset collection information.

[0129] The fake image determination module is configured to determine that the examinee image is a fake image when the examinee information does not match the preset examinee information and / or the collection information does not match the preset collection information.

[0130] As a further limitation of the technical scheme of the embodiment of the present application, it specifically further includes the following units:

[0131] The image to be verified is collected by the image to be verified collecting unit when the reference image is a real image, and the image to be verified is obtained.

[0132] The identity of the examinee to be verified is verified by the identity verifying unit using the reference image and the image to be verified.

[0133] It should be understood that although each step in the flowchart of each embodiment of the present application is shown in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least a part of the steps in each embodiment can include multiple sub-steps or multiple stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these sub-steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least a part of other steps or sub-steps or stages of other steps.

[0134] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by a computer program instructing related hardware. The program can be stored in a non-volatile computer readable storage medium, and when the program is executed, it can include the processes of the above-mentioned embodiments of each method. Any reference to memory, storage, database or other medium used in each embodiment provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0135] Each technical feature of the above embodiments can be combined arbitrarily. In order to make the description concise, all possible combinations of each technical feature in the above embodiments are not described, but as long as the combination of these technical features does not exist, it should be considered as the scope of the present application.

[0136] The above embodiments only express several implementation manners of the present application, which are described in a more specific and detailed manner, but should not be understood as a limitation on the patent scope of the present application. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present application, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

[0137] The above only is the preferred embodiment of the present application, and does not limit the present application, and any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A watermarking steganography method for educational examination images, characterized in that, Specifically, the following steps are included: Obtain the candidate's image and exam information to be watermarked; The candidate image is subjected to Fourier transform to obtain the spectrum of the candidate image; A watermark image is generated using the exam information, and a Fourier transform is performed on the watermark image to obtain its spectrum. The spectrograms of the candidate image and the watermark image are fused to obtain the spectrogram after the watermark is written. Perform an inverse Fourier transform on the spectrogram after watermarking to obtain the candidate image after watermarking. The Fourier transform of the candidate image is used to obtain the spectrum of the candidate image, specifically including the following steps: Perform a Fourier transform on the candidate image to obtain the first spectrogram of the candidate image; The first spectrogram is filtered by a noise filter to obtain a filtered second spectrogram, which is used as the image content spectrogram of the candidate's image. A third spectrum is obtained by performing a difference processing on the first spectrum and the second spectrum, which is used as the noise spectrum of the candidate's image; The process of generating a watermark image using the exam information and performing a Fourier transform on the watermark image to obtain its spectrum includes the following steps: The exam information is encrypted to obtain ciphertext; The ciphertext is written into a preset watermark image template to obtain a watermark image; The watermark image is subjected to Fourier transform to obtain the spectrum of the watermark image; The spectrograms of the candidate image and the watermark image are fused to obtain the spectrogram after watermarking, specifically including the following steps: The noise spectrum of the candidate image and the spectrum of the watermark image are fused to obtain a fused noise spectrum. The fused noise spectrum is fused with the image content spectrum of the candidate's image to obtain the spectrum after watermarking.

2. The watermarking steganography method for educational examination images as described in claim 1, characterized in that, The process of obtaining the candidate image and examination information to be watermarked includes the following steps: JPG images of the candidates will be collected as candidate images to be watermarked; The system obtains the candidate information and the image acquisition information of the candidate. The candidate information includes at least one of the following: examination number, candidate name, and candidate identity information. The image acquisition information includes at least one of the following: candidate type, image acquisition method, and image acquisition platform. The candidate information and the collected information are encoded into examination information.

3. A watermark recognition method for educational examination images, characterized in that, Specifically, the following steps are included: Obtain a reference image to be identified, wherein the reference image is an image after watermarking is applied using the watermarking steganography method for educational examination images according to any one of claims 1-2; The reference image is subjected to Fourier transform to obtain the spectrum of the reference image; The spectrum of the watermark is separated from the spectrum of the watermark. The watermark image is obtained by performing an inverse Fourier transform on the spectrogram of the watermark. The authenticity of the reference image is determined based on the watermark image.

4. The watermark recognition method for educational examination images as described in claim 3, characterized in that, The process of identifying the authenticity of the reference image based on the watermark image specifically includes the following steps: Extract exam information from the watermark image; When the exam information is encrypted, a preset encryption algorithm is used to decrypt the encrypted information to obtain the plaintext exam information. The exam information includes candidate information and the acquisition information of the reference image. The candidate information includes at least one of the following: exam number, candidate name, and candidate identity information. The acquisition information includes at least one of the following: candidate type, image acquisition method, and image acquisition platform. When the candidate information matches the preset candidate information and the collected information matches the preset collected information, the reference image is determined to be a real image. If the candidate information does not match the preset candidate information and / or the collected information does not match the preset collected information, the reference image is determined to be a forged image.

5. The watermark recognition method for educational examination images as described in claim 3, characterized in that, After identifying the authenticity of the reference image based on the watermark image, the process further includes the following steps: When the reference image is a real image, an image of the candidate whose identity is to be verified is acquired to obtain the image to be verified; The identity of the candidate to be verified is verified using the reference image and the image to be verified.

6. A watermarking steganography system for educational examination images, characterized in that, Specifically, it includes the following units: The image and exam information acquisition unit is used to acquire the candidate's image and exam information to be watermarked; The candidate image frequency domain conversion unit is used to perform Fourier transform on the candidate image to obtain the spectrum of the candidate image; The watermark frequency domain conversion unit is used to generate a watermark image using the examination information and perform a Fourier transform on the watermark image to obtain the spectrum of the watermark image. The watermark writing unit is used to fuse the spectrogram of the candidate image and the spectrogram of the watermark image to obtain the spectrogram after watermarking. The inverse Fourier transform unit is used to perform an inverse Fourier transform on the spectrogram after the watermark is written, so as to obtain the candidate image after the watermark is written. The candidate image frequency domain conversion unit specifically includes the following modules: The candidate image frequency domain conversion module is used to perform Fourier transform on the candidate image to obtain the first spectrum of the candidate image; The image content spectrum acquisition module is used to filter the first spectrum through a noise filter to obtain a filtered second spectrum, which is used as the image content spectrum of the candidate's image. The noise spectrum acquisition module is used to obtain a third spectrum by performing difference processing on the first spectrum and the second spectrum, so as to serve as the noise spectrum of the candidate's image; The watermark frequency domain conversion unit includes the following modules: An encryption module is used to encrypt the examination information to obtain ciphertext; The watermark image generation module is used to write the ciphertext into a preset watermark image template to obtain a watermark image; The watermark frequency domain conversion module is used to perform Fourier transform on the watermark image to obtain the spectrum of the watermark image; The watermark writing unit specifically includes the following modules: The noise and watermark fusion module is used to fuse the noise spectrum of the candidate image and the spectrum of the watermark image to obtain a fused noise spectrum. The noise and candidate image content fusion module is used to fuse the fused noise spectrum with the image content spectrum of the candidate image to obtain the spectrum after watermarking.

7. A watermark recognition system for educational examination images, characterized in that, Specifically, it includes the following units: The image acquisition unit is used to acquire a reference image to be identified, wherein the reference image is an image after watermarking is applied using the watermarking steganography method for educational examination images according to any one of claims 1-2; An image frequency domain conversion unit is used to perform a Fourier transform on the reference image to obtain the spectrum of the reference image; A watermark spectrum separation unit is used to separate the spectrum of the watermark from the spectrum. The watermark spectrum time-domain conversion unit is used to perform an inverse Fourier transform on the spectrum of the watermark to obtain a watermark image. A reference image authenticity recognition unit is used to identify the authenticity of the reference image based on the watermark image.

Images