Double-image block-based image processing method and device and storage medium

Abstract

The invention relates to a double-image block-based image processing method and device and a storage medium, and the method comprises the steps: copying an original carrier image into two carrier images which are the same as the original image, dividing each carrier image into a plurality of reference pixel blocks and non-reference pixel blocks, each pixel block comprises a plurality of pixel points, the reference pixel block between the two carrier images corresponds to the non-reference pixel block of the other carrier image in position, and the absolute difference between each pixel point in each non-reference pixel block and the pixel average value of the adjacent reference pixel block is calculated; according to the method, whether the secret information can be embedded into the pixel is judged according to the absolute difference value, the digit of the secret information which can be embedded into the pixel is calculated according to the absolute difference value, and the secret pheromone is read according to the digit to complete embedding, so that most of downsampling and expansion steps adopted based on an interpolation algorithm are avoided; and the original carrier image and the secret information can be completely recovered, so that true reversibility is realized.

Description

Technical Field

[0001] The present invention relates to the field of image steganography, and in particular to a block-based image processing method, device and storage medium for dual images. Background Art

[0002] Information security refers to the process of protecting information and information systems from unauthorized access, use, disclosure, damage, modification or destruction. Information hiding is a key technical means in this protection process. Information hiding aims to embed information into digital media, such as images, audio, video, etc., so that only authorized users can access or extract this information. This technology has a wide range of applications in copyright protection, content authentication, data confidentiality and multimedia security. Information hiding technology has developed rapidly since the late 20th century and is mainly divided into two types: reversible information hiding and irreversible information hiding. Traditional information hiding methods are achieved by embedding secret information in host files, but this often comes at the expense of the integrity and recoverability of the host files. In recent years, reversible data hiding (RDH) technology has attracted widespread attention due to its ability to embed and recover information losslessly.

[0003] Reversible information hiding technology is a data hiding method that can embed secret information into a carrier without destroying the quality of the original carrier (such as images, audio or video), and can completely restore the original carrier after extracting the information. This technology has important application value in the field of information security, especially in copyright protection, data security, privacy protection, etc. The core of reversible information hiding technology lies in "lossless" and "reversible". Lossless means that the process of embedding information will not cause any quality loss to the original carrier; reversible means that the hidden information can be extracted from the carrier and the original carrier can be restored without leaving any traces. The goal of the reversible information hiding algorithm is to embed as much secret information as possible while maintaining image quality.

[0004] In reversible information hiding techniques, interpolation-based algorithms have attracted attention due to their ability to provide higher data hiding capacity. However, traditional interpolation-based algorithms have two main problems: 1. They are not truly reversible, and 2. They introduce high distortion to the carrier image. Summary of the invention

[0005] Based on this, the present invention aims to provide a dual-image block-based image processing method, which can at least solve one problem of the traditional reversible information hiding algorithm based on interpolation. Specifically, it includes the following steps:

[0006] Copying the original carrier image into a first carrier image and a second carrier image;

[0007] The first carrier image is steganographically written by the following steps: the first carrier image is divided into blocks, and is divided into at least one first reference pixel block and at least one first non-reference pixel block; each first reference pixel block contains a plurality of first pixel points, and each first non-reference pixel block contains a plurality of first non-reference pixel points; the pixel values ​​of the first pixel points of each first reference pixel block are summed and averaged to obtain the first pixel average value of each first reference pixel block; the first pixel average value in each first reference pixel block is subtracted from the pixel value of each first non-reference pixel point of the adjacent first non-reference pixel block and the absolute value is calculated to obtain the absolute difference between each first non-reference pixel point and the corresponding first pixel average value; when the absolute difference is less than a preset threshold, the first non-reference pixel point is marked as a first embeddable point, and the number of bits of embeddable secret information of the first embeddable point is calculated; according to the number of bits of embeddable secret information of each first embeddable point, the corresponding number of bits of secret information is intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding first embeddable point, and the first steganographic image is obtained after all the first embeddable points are embedded with the secret information;

[0008] The second carrier image is steganographically written by the following steps: the second carrier image is divided into at least one second reference pixel block and at least one second non-reference pixel block; each second reference pixel block contains a plurality of second pixel points, each second non-reference pixel block contains a plurality of second non-reference pixel points; the second reference pixel block corresponds to the position of the first non-reference pixel block, and the second non-reference pixel block corresponds to the position of the first reference pixel block; the pixel values ​​of the second pixel points of each second reference pixel block are summed and averaged to obtain the second pixel average value of each second reference pixel block; ... The difference between the pixel value of the two-pixel average value and the pixel value of each second non-reference pixel point of the second non-reference pixel block adjacent to the two-pixel average value is calculated, and the absolute value is calculated to obtain the absolute difference between each second non-reference pixel point and the corresponding second pixel average value; when the absolute difference is less than a preset threshold, the second non-reference pixel point is marked as a second embeddable point, and the number of bits of embeddable secret information of the second embeddable point is calculated; according to the number of bits of embeddable secret information of each second embeddable point, the corresponding number of bits of secret information is intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding second embeddable point, and the second secret image is obtained after all the second embeddable points are embedded with the secret information.

[0009] The original carrier image is copied into two carrier images that are the same as the original image, and each carrier image is divided into a number of reference pixel blocks and non-reference pixel blocks. Each pixel block includes a number of pixel points, and the reference pixel block between the two carrier images corresponds to the position of the non-reference pixel block of the other carrier image. The absolute difference between each pixel point in each non-reference pixel block and the pixel average value of its adjacent reference pixel block is calculated to determine whether the pixel can be embedded with secret information, and the number of secret information bits that can be embedded in the pixel is calculated based on the absolute difference. The secret pheromone is read by the number of bits to complete the embedding, avoiding the downsampling and expansion steps used in most interpolation-based algorithms, so that the original carrier image and the secret information can be completely restored, thereby achieving true reversibility.

[0010] Furthermore, the number of bits of embedded secret information for each embeddable point is calculated by the following formula:

[0011]

[0012] in is the absolute difference of the corresponding embeddable points.

[0013] Furthermore, before embedding secret information at any embeddable point, the pixel value of the corresponding embeddable point is processed by the following formula:

[0014]

[0015] in is the number of embeddable secret information bits corresponding to the embeddable point.

[0016] Further, embedding the secret information into the corresponding first embeddable point, and / or embedding the secret information into the corresponding second embeddable point specifically includes:

[0017] The intercepted secret information is converted into a corresponding decimal number, and then the decimal number is converted into a binary number, and the binary number is associated with the corresponding first embeddable point and / or the second embeddable point.

[0018] Furthermore, the specific formula for converting the decimal number into a binary number is:

[0019]

[0020] in The decimal number that needs to be converted.

[0021] Through this conversion method, the secret information is read by digit and converted into a decimal number. Then, the original pixel value range [0-(2 n -1)] becomes [-2n-1 -2 n-1 -1], after embedding, the pixel change of the embedding point is small, which greatly improves the image quality and greatly enhances the confidentiality of image steganography.

[0022] Furthermore, the image restoration step is also included:

[0023] Extracting all first reference pixel blocks from the first secret image in a first carrier image block manner, and extracting all second reference pixel blocks from the second secret image in a second carrier image block manner, and obtaining the original carrier image based on the extracted first reference pixel blocks and second reference pixel blocks;

[0024] The original carrier image is processed in a block manner in the same manner as the first carrier image, and the original carrier image is processed in the steganographic step of the first carrier image until the anti-overflow processing is completed, and then the first carrier image is subtracted from the processed original carrier image to obtain a plurality of first secret information embedded in the first steganographic image;

[0025] The original carrier image is processed in a block manner in the block manner of the second carrier image, and the original carrier image is processed in the steganographic step of the second carrier image until the anti-overflow processing is completed, and then the second carrier image is subtracted from the processed original carrier image to obtain a plurality of second secret information embedded in the second steganographic image;

[0026] Each first secret information and each second secret information is converted into a corresponding decimal number, and then each decimal number is converted into a corresponding binary number; all binary numbers are sequentially concatenated to obtain a complete secret information.

[0027] On the other hand, based on any of the above-mentioned dual-image block-based image processing methods, the present invention further provides a dual-image block-based image processing device, comprising an image steganography unit, which includes an image replication module, a first image steganography module, and a second image steganography module;

[0028] The image copying module is used to copy the original carrier image into a first carrier image and a second carrier image;

[0029] The first image steganography module includes: a first block submodule, used to block the first carrier image into at least one first reference pixel block and at least one first non-reference pixel block; wherein each first reference pixel block includes a plurality of first pixel points, and each first non-reference pixel block includes a plurality of first non-reference pixel points;

[0030] A first pixel average value calculation submodule, used for summing and averaging the pixel values ​​of the first pixel points of each first reference pixel block to obtain a first pixel average value of each first reference pixel block;

[0031] A first absolute difference calculation submodule is used to calculate the difference and absolute value of the first pixel average value in each first reference pixel block and the pixel value of each first non-reference pixel point in the adjacent first non-reference pixel block, so as to obtain the absolute difference between each first non-reference pixel point and the corresponding first pixel average value;

[0032] A first embeddable point calculation submodule, configured to mark the first non-reference pixel point as a first embeddable point when the absolute difference is less than a preset threshold, and calculate the number of bits of embeddable secret information of the first embeddable point;

[0033] A first image encryption submodule, used for intercepting secret information of corresponding bits from the secret information to be embedded according to the number of bits of embeddable secret information at each first embeddable point, and embedding the secret information into the corresponding first embeddable point, and obtaining a first encrypted image after all the first embeddable points are embedded with the secret information;

[0034] The second image steganography module includes: a second block submodule, which is used to block the second carrier image into at least one second reference pixel block and at least one second non-reference pixel block; wherein each second reference pixel block includes a plurality of second pixel points, and each second non-reference pixel block includes a plurality of second non-reference pixel points; the second reference pixel block corresponds to the position of the first non-reference pixel block, and the second non-reference pixel block corresponds to the position of the first reference pixel block;

[0035] A second pixel absolute difference calculation module, used for summing and averaging the pixel values ​​of the second pixel points of each second reference pixel block to obtain a second pixel average value of each second reference pixel block;

[0036] A second absolute difference calculation submodule is used to calculate the difference and absolute value of the second pixel average value in each second reference pixel block and the pixel value of each second non-reference pixel point in the adjacent second non-reference pixel block, so as to obtain the absolute difference between each second non-reference pixel point and the corresponding second pixel average value;

[0037] A second embeddable point calculation submodule, configured to mark the second non-reference pixel point as a second embeddable point when the absolute difference is less than a preset threshold, and calculate the number of embeddable secret information bits of the second embeddable point;

[0038] The second image encryption submodule is used to intercept the corresponding number of bits of secret information from the secret information to be embedded according to the number of bits of embeddable secret information at each second embeddable point, and embed the secret information into the corresponding second embeddable point. After all the second embeddable points are embedded with secret information, a second encrypted image is obtained.

[0039] Furthermore, an image restoration unit is included, which includes:

[0040] an original carrier image recovery module, for extracting all first reference pixel blocks from the first secret image in a first carrier image block manner, and for extracting all second reference pixel blocks from the second secret image in a second carrier image block manner, and obtaining the original carrier image according to the extracted first reference pixel blocks and second reference pixel blocks;

[0041] The first information extraction module is used to process the original carrier image in a block-by-block manner of the first carrier image, and process the original carrier image in a steganographic step of the first carrier image until the anti-overflow process is completed, and then the first carrier image is subtracted from the processed original carrier image to obtain a plurality of first secret information embedded in the first steganographic image;

[0042] The second information extraction module is used to process the original carrier image in a block-by-block manner of the second carrier image, and process the original carrier image in a steganographic step of the second carrier image until the anti-overflow process is completed, and then the second carrier image is subtracted from the processed original carrier image to obtain a plurality of second secret information embedded in the second steganographic image;

[0043] The information conversion module is used to convert each first secret information and each second secret information into a corresponding decimal number, and then convert each decimal number into a corresponding binary number; all binary numbers are sequentially spliced ​​to obtain complete secret information.

[0044] On the other hand, based on the same inventive concept, the present invention also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the steps of a dual-image block-based image processing method described in any one of the above methods.

[0045] The present invention performs segmented steganography of secret information through dual images, stores the secret information in the pixel points of two carrier images in sequence, and makes non-overlapping block division of the two carrier images respectively, so that the steganographic parts of the secret information of the first secret image and the second secret image are completely non-overlapping, so as to facilitate rapid extraction when the secret information needs to be recovered from the secret image. In addition, in order to prevent excessive information steganography by traditional interpolation algorithms, the present invention also evaluates the pixel points in each non-reference pixel block, and only the pixel points that meet the embeddable conditions will be used as embeddable points to embed the secret information, and the capacity of the embeddable points is calculated, so as to write the most secret information under the premise of ensuring confidentiality and security. In addition, since the non-reference pixel blocks of the first secret image and the reference pixel blocks of the second secret image, and the non-reference pixel blocks of the second secret image and the reference pixel blocks of the first secret image are completely overlapped when the first carrier image and the second carrier image are divided into blocks, the original carrier image can be quickly restored by extracting the corresponding reference pixel blocks according to the block division order when each carrier image is divided into blocks, and then the original carrier image is steganographically written according to the steganographic steps of the first carrier image and the steganographic steps of the second carrier image, respectively, until the first embedding point is processed with anti-overflow and the second embedding point is processed with anti-overflow, respectively. At this time, the first carrier image is subtracted from the processed original carrier image to obtain multiple first secret information embedded in the first secret image, and the second carrier image is subtracted from the processed original carrier image to obtain multiple second secret information embedded in the second secret image. Then, the base conversion and combination are performed in sequence to restore the complete secret information. Since lossy operations such as frequency conversion and filtering are not required, the secret information obtained at this time is not lost, thereby achieving true reversibility of steganography.

[0046] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 A flowchart of an exemplary image steganographic step of a block-based image processing method for dual images provided by the present invention;

[0048] Figure 2 For execution Figure 1 A structural block diagram of an image steganography unit showing the image steganography steps;

[0049] Figure 3 is a schematic diagram of an exemplary image division region;

[0050] Figure 4 A flowchart of an exemplary image restoration step of a block-based image processing method for dual images provided by the present invention;

[0051] Figure 5 For execution Figure 4A structural block diagram of a restoration unit of the image restoration step shown; DETAILED DESCRIPTION

[0052] It should be known that any image is composed of multiple pixels. Pixels, also called picture elements or pixel points, are the smallest units that make up a digital image. Some existing interpolation algorithms expand the original carrier image by upsampling, increase the number of image pixels to achieve image expansion, write steganographic data into the expanded pixel points of the image, and then restore the image by downsampling during data recovery. However, some data of the original carrier image has been lost during the upsampling and downsampling process, so the process of image steganography and recovery cannot be considered truly reversible.

[0053] In response to the problems found in the above research, the present invention provides a block-based image processing method for dual images, which includes an image steganography step and an image recovery step. The image steganography step is to hide the secret information in two carrier images to generate two secret images; the image recovery step is to completely recover the secret information and the two carrier images from the two secret images. The following two parts will be specifically explained.

[0054] (I) Image steganography

[0055] See also Figure 1 , Figure 1 A flowchart of an exemplary image steganography step provided by the present invention, Figure 2 For execution Figure 1 The structural block diagram of the image steganography unit of the image steganography step, the image steganography unit is used to copy the carrier image, and process the two carrier images respectively, and finally hide the secret information in the two carrier images to obtain the first secret image and the second secret image, the image steganography unit includes an image copying module 10, a first image steganography module and a second image steganography module. Specifically, the image steganography step includes:

[0056] S10 : copying the original carrier image into a first carrier image and a second carrier image; step S10 is performed by the image copying module 10 .

[0057] Copy the original carrier image I(x,y) into the first carrier image I ′ (x, y) and a second carrier image I″(x, y), such that I″(x, y)=I ′ (x,y)=I(x,y).

[0058] The first image steganography module includes a first block division submodule 20.A, a first pixel average value calculation submodule 30.A, a first absolute difference calculation submodule 40.A, a first embeddable point calculation submodule 50.A and a first image steganography submodule 60.A.

[0059] The second image steganography module includes a second block division submodule 20.B, a second pixel average value calculation submodule 30.B, a second absolute difference calculation submodule 40.B, a second embeddable point calculation submodule 50.B and a second image steganography submodule 60.B.

[0060] During the image steganography process, the first image steganography module and the second image steganography module can be executed at the same time.

[0061] The first blocking submodule 20.A executes step S20.A: blocks the first carrier image and sets reference pixel blocks and non-reference pixel blocks according to a fixed pixel interval.

[0062] The second blocking submodule 20.B executes step S20.B: blocks the second carrier image and sets reference pixel blocks and non-reference pixel blocks according to a fixed pixel interval; wherein the position of the reference pixel block of the first carrier image corresponds to the position of the non-reference pixel block of the second carrier image.

[0063] The present invention divides the first carrier image and the second carrier image into non-overlapping blocks, each block contains N*M pixels; each block of the carrier image is marked as a reference pixel block and a non-reference pixel block, and it is only necessary to ensure that the positions of the reference pixel blocks of the first carrier image and the non-reference pixel blocks of the second carrier image correspond one-to-one, and the positions of the non-reference pixel blocks of the first carrier image and the reference pixel blocks of the second carrier image correspond one-to-one. Figure 3 In order to better explain the present invention, in a specific embodiment, the reference pixel block and the non-reference pixel block of each carrier image are both 2*2 pixel blocks, each pixel block includes four pixels, the non-reference pixel block is identified by a shadow block, and the non-shadow block identifies the reference pixel block. The non-reference pixel block is an area for carrying secret information. The P of the first carrier image m is a non-reference pixel block, P m+1 is the reference pixel block, and the second carrier image { m is the reference pixel block, { m+1 is a non-reference pixel block, where m is an odd number.

[0064] The first pixel average value calculation submodule 30.A executes step S30.A: summing and averaging the pixel values ​​of the first pixel points of each first reference pixel block to obtain the first pixel average value of each first reference pixel block.

[0065] The first absolute difference calculation submodule 40.A executes step S40.A: subtracts the first pixel average value in each first reference pixel block from the pixel value of each first non-reference pixel point in its adjacent first non-reference pixel block and calculates the absolute value, so as to obtain the absolute difference between each first non-reference pixel point and the corresponding first pixel average value.

[0066] The first embeddable point calculation submodule 50.A executes step S50.A: when the absolute difference is less than a preset threshold, the first non-reference pixel point is marked as a first embeddable point, and the number of embeddable secret information bits of the first embeddable point is calculated.

[0067] The second pixel average value calculation submodule 30.B executes step S30.B: summing and averaging the pixel values ​​of the second pixels of each second reference pixel block to obtain the second pixel average value of each second reference pixel block.

[0068] The second absolute difference calculation submodule 40.B executes step S40.B: subtracts the second pixel average value in each second reference pixel block from the pixel value of each second non-reference pixel point in its adjacent second non-reference pixel block and calculates the absolute value to obtain the absolute difference between each second non-reference pixel point and the corresponding second pixel average value.

[0069] The second embeddable point calculation submodule 50.B executes step S50.B: when the absolute difference is less than a preset threshold, the second non-reference pixel point is marked as a second embeddable point, and the number of embeddable secret information bits of the second embeddable point is calculated.

[0070] In order to improve the confidentiality of image steganography, secret information is not embedded in every pixel in the non-reference image. The present invention first calculates the pixel average value of each reference pixel block, and then calculates the absolute difference between each pixel in the non-reference pixel block adjacent to the reference pixel block and the pixel average value based on the pixel average value. Taking a first reference pixel block of the first carrier image and its adjacent first non-reference pixel block as an example, the calculation process of the absolute difference is as follows:

[0071] First, the pixel average value of the first reference pixel block is calculated

[0072]

[0073] Among them, p m+1 (1,1),p m+1 (1,2), p m+1 (2,1),p m+1 (2,2) are the pixel values ​​of four pixels in the reference pixel block.

[0074] Then calculate the absolute difference between each pixel in the first non-reference pixel block Pm and the pixel average value

[0075]

[0076] Among them, (x,y)∈{(1,1),(1,2),(2,1),(2,2)}.

[0077] therefore is an array containing four values, whose values ​​correspond to the absolute differences between the four pixels in the non-reference pixel block and the pixel average value.

[0078] The absolute difference of each pixel point of each non-reference pixel block is judged, and only those that meet Only pixels with The pixels that meet the conditions are not used to embed secret information, so the pixels that meet the conditions are marked as the first embeddable points. However, the information that can be embedded in each pixel is also limited. In order to ensure the confidentiality of the embedded information, the number of bits of embeddable secret information for each embeddable point is calculated by the following formula

[0079]

[0080] in is the absolute difference of the corresponding embeddable points. It is used to read the corresponding number of bits of secret information for each embedded point, thus improving the efficiency of steganography.

[0081] The first image encryption submodule 60.A executes step S60.A: according to the number of bits of embeddable secret information at each first embeddable point, a corresponding number of bits of secret information are intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding first embeddable point. After all the first embeddable points are embedded with secret information, a first encryption image is obtained.

[0082] The second image encryption submodule 60.B executes step S60.B: according to the number of bits of embeddable secret information at each second embeddable point, a corresponding number of bits of secret information are intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding second embeddable point. After all the second embeddable points are embedded with secret information, a second encryption image is obtained.

[0083] Embed secret information into each embeddable point according to the number of bits of embeddable secret information at each embeddable point, and embed the secret information into the embeddable points of the first carrier image and the embeddable points of the second carrier image in batches. Read from the secret information stream to be embedded Convert the secret information into decimal number Then convert the decimal number Convert to binary The preferred specific conversion formula is as follows

[0084]

[0085] Through this conversion method, the secret information is read by digit and converted into a decimal number. Then, the original pixel value range [0-(2 n -1)] becomes [-2 n-1 -2 n-1 -1], after embedding, the pixel change of the embedding point is small, which greatly improves the image quality and greatly enhances the confidentiality of image steganography.

[0086] The final pixel value after embedding is:

[0087]

[0088] At this time, the pixel value of each non-reference pixel block does not exceed the preset threshold, so it has high confidentiality. In addition, by alternating double images to carry secret information, it has high resistance to steganographic attacks, so the security of steganography is also high.

[0089] In addition, in order to avoid overflow problems, the present invention further includes: processing the pixel value of the embeddable point by the following formula before embedding the secret information into each embeddable point:

[0090]

[0091] in is the number of embeddable secret information bits corresponding to the embeddable point.

[0092] The present invention performs segmented steganography of secret information through dual images, stores the secret information in pixel blocks of two carrier images in sequence, and performs non-overlapping block division on the two carrier images respectively, so that the steganographic parts of the secret information of the first secret image and the second secret image are completely non-overlapping, so as to facilitate rapid extraction when the secret information needs to be restored from the secret image. In addition, in order to prevent excessive information steganography by traditional interpolation algorithms, the present invention also evaluates the pixel points in each non-reference pixel block, and only the pixel points that meet the embeddable conditions will be used as embeddable points to embed the secret information, and the capacity of the embeddable points is calculated, so as to write the most secret information while ensuring confidentiality and security.

[0093] (II) Image restoration part

[0094] According to the image steganography step of the above image processing method, two steganographic images are obtained. Due to the setting of the first carrier image and the second carrier image in the block stage of the reference pixel block, the non-reference pixel block of the first carrier image corresponds to the reference pixel block of the second carrier image, and the non-reference pixel block of the second carrier image corresponds to the reference pixel block of the first carrier image. This greatly facilitates the subsequent recovery of the original carrier image and the recovery of the secret information. Therefore, please refer to Figure 4 and Figure 5 The image processing method of the present invention further includes an image restoration step, and the image processing device further includes an image restoration unit for quickly restoring the carrier image and the secret information from the first secret image and the second secret image, and the restoration unit includes an inverse blocking module 70, a first information extraction module 80.A, a second information extraction module 80.B and an information conversion module 90; wherein the image restoration step is performed by the image restoration unit, specifically:

[0095] The original carrier image recovery module 70 executes step S70: extracting all first reference pixel blocks from the first secret image in a first carrier image block manner, and extracting all second reference pixel blocks from the second secret image in a second carrier image block manner, and obtaining the original carrier image according to the extracted first reference pixel blocks and second reference pixel blocks;

[0096] The first information extraction module 80.A executes step S80.A: the original carrier image is processed in a block manner in the block manner of the first carrier image, and the original carrier image is processed in the steganographic step of the first carrier image until the anti-overflow processing is completed, and then the first carrier image is subtracted from the processed original carrier image to obtain a plurality of first secret information embedded in the first steganographic image;

[0097] The second information extraction module 80.B executes step S80.B: the original carrier image is divided into blocks in the manner of the second carrier image, and the original carrier image is processed in the steganographic step of the second carrier image until the anti-overflow processing is completed, and then the second carrier image is subtracted from the processed original carrier image to obtain a plurality of second secret information embedded in the second steganographic image;

[0098] After the original carrier image is restored, the secret information needs to be restored. Generally speaking, the corresponding pixel points between the images can be directly subtracted to complete the acquisition of the secret image information. However, due to the pixel overflow prevention processing for each embeddable point during image steganography, the pixels of some embeddable points have changed compared with the original pixels, so the image subtraction cannot be performed directly. At this time, the pixel points of the embeddable points must be calculated through the image steganography steps adopted until the pixel value of each embeddable point after the overflow prevention processing is obtained. Only then can the image subtraction be performed to extract the secret information. This further improves the security of image steganography.

[0099] The formula for extracting the embedded secret information of each pixel of the encrypted image is as follows:

[0100]

[0101] where p ′ (x, y) is the pixel value of a pixel in the original carrier image, and p(x, y) is the pixel value of a reference pixel at the corresponding position in the encrypted image.

[0102] When there is secret information, The value of is not equal to 0. When the value of is equal to 0, it means that there is no secret information. Therefore, there is no need to downsample the secret image to perform image transformation, thereby extracting the secret information and accelerating the recovery of the secret information.

[0103] The information conversion module 90 executes step S90: converting the obtained secret information into a decimal number, and then converting the decimal number into a binary number; and concatenating all the binary numbers in sequence to obtain the complete secret information.

[0104] According to the following formula Convert to decimal:

[0105]

[0106] Finally, convert the decimal number to binary.

[0107] In summary, the present invention performs segmented steganography of secret information through dual images, stores the secret information in the pixels of two carrier images in sequence, and divides the two carrier images into non-overlapping blocks respectively, so that the steganographic parts of the secret information of the first carrier image and the second carrier image are completely non-overlapping, so as to facilitate rapid extraction when the secret information needs to be restored from the carrier image. In addition, in order to prevent excessive information steganography by traditional interpolation algorithms, the present invention also evaluates the pixel points in each non-reference pixel block, and only the pixel points that meet the embeddable conditions will be used as embeddable points to embed the secret information, and the capacity of the embeddable points is calculated, so as to write the most secret information while ensuring confidentiality and security. In addition, since the non-reference pixel blocks of the first secret image and the reference pixel blocks of the second secret image, and the non-reference pixel blocks of the second secret image and the reference pixel blocks of the first secret image are completely overlapped when the first carrier image and the second carrier image are divided into blocks, the original carrier image can be quickly restored by extracting the corresponding reference pixel blocks according to the block division order when each carrier image is divided into blocks, and then the original carrier image is steganographically written according to the steganographic steps of the first carrier image and the steganographic steps of the second carrier image, respectively, until the first embedding point is processed with anti-overflow and the second embedding point is processed with anti-overflow, respectively. At this time, the first carrier image is subtracted from the processed original carrier image to obtain multiple first secret information embedded in the first secret image, and the second carrier image is subtracted from the processed original carrier image to obtain multiple second secret information embedded in the second secret image. Then, the base conversion and combination are performed in sequence to restore the complete secret information. Since lossy operations such as frequency conversion and filtering are not required, the secret information obtained at this time is not lost, thereby achieving true reversibility of steganography.

[0108] An embodiment of the present application further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the block-based image processing method for dual images described in any one of the above embodiments is implemented.

[0109] The present invention may take the form of a computer program product implemented on one or more storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing program code. Computer-readable storage media include permanent and non-permanent, removable and non-removable media, and information storage can be achieved by any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include but are not limited to: phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technology, read-only compact disk read-only memory (CD-ROM), digital versatile disk (DVD) or other optical storage, magnetic cassettes, magnetic tape magnetic disk storage or other magnetic storage devices or any other non-transmission medium that can be used to store information that can be accessed by a computing device.

[0110] The above-mentioned embodiments only express several implementation methods of the present invention, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A block-based image processing method for dual images, It is characterized in that Image steganography steps included: Copying the original carrier image into a first carrier image and a second carrier image; The first carrier image is steganographically written by the following steps: the first carrier image is divided into blocks, and is divided into at least one first reference pixel block and at least one first non-reference pixel block; each first reference pixel block contains a plurality of first pixel points, and each first non-reference pixel block contains a plurality of first non-reference pixel points; the pixel values ​​of the first pixel points of each first reference pixel block are summed and averaged to obtain the first pixel average value of each first reference pixel block; the first pixel average value in each first reference pixel block is subtracted from the pixel value of each first non-reference pixel point of the adjacent first non-reference pixel block and the absolute value is calculated to obtain the absolute difference between each first non-reference pixel point and the corresponding first pixel average value; when the absolute difference is less than a preset threshold, the first non-reference pixel point is marked as a first embeddable point, and the number of bits of embeddable secret information of the first embeddable point is calculated; according to the number of bits of embeddable secret information of each first embeddable point, the corresponding number of bits of secret information is intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding first embeddable point, and the first steganographic image is obtained after all the first embeddable points are embedded with the secret information; The second carrier image is steganographically written by the following steps: the second carrier image is divided into at least one second reference pixel block and at least one second non-reference pixel block; each second reference pixel block contains a plurality of second pixel points, each second non-reference pixel block contains a plurality of second non-reference pixel points; the second reference pixel block corresponds to the position of the first non-reference pixel block, and the second non-reference pixel block corresponds to the position of the first reference pixel block; the pixel values ​​of the second pixel points of each second reference pixel block are summed and averaged to obtain the second pixel average value of each second reference pixel block; ... The difference between the pixel value of the two-pixel average value and the pixel value of each second non-reference pixel point of the second non-reference pixel block adjacent to the two-pixel average value is calculated, and the absolute value is calculated to obtain the absolute difference between each second non-reference pixel point and the corresponding second pixel average value; when the absolute difference is less than a preset threshold, the second non-reference pixel point is marked as a second embeddable point, and the number of bits of embeddable secret information of the second embeddable point is calculated; according to the number of bits of embeddable secret information of each second embeddable point, the corresponding number of bits of secret information is intercepted from the secret information to be embedded, and the secret information is embedded into the corresponding second embeddable point, and the second secret image is obtained after all the second embeddable points are embedded with the secret information.

2. The block-based image processing method of dual images according to claim 1, It is characterized in that The number of bits of embedded secret information for each embeddable point is calculated by the following formula in, is the absolute difference of the corresponding embeddable points.

3. The block-based image processing method of dual images according to claim 2, It is characterized in that Before embedding secret information at any embeddable point, the pixel value of the corresponding embeddable point is processed to prevent overflow using the following formula: in is the number of embeddable secret information bits corresponding to the embeddable point.

4. The block-based image processing method of dual images according to claim 3, It is characterized in that Embedding the secret information into the corresponding first embeddable point, and / or embedding the secret information into the corresponding second embeddable point, specifically includes: The intercepted secret information is converted into a corresponding decimal number, and then the decimal number is converted into a binary number, and the binary number is embedded into the corresponding first embeddable point, or the second embeddable point.

5. The block-based image processing method of dual images according to claim 4, It is characterized in that The specific formula for converting the decimal number into a binary number is: in The decimal number that needs to be converted.

6. The block-based image processing method of dual images according to claim 5, It is characterized in that Also includes image restoration steps: Extracting all first reference pixel blocks from the first secret image in a first carrier image block manner, and extracting all second reference pixel blocks from the second secret image in a second carrier image block manner, and obtaining the original carrier image based on the extracted first reference pixel blocks and second reference pixel blocks; The original carrier image is processed in a block manner in the same manner as the first carrier image, and the original carrier image is processed in the steganographic step of the first carrier image until the anti-overflow processing is completed, and then the first carrier image is subtracted from the processed original carrier image to obtain a plurality of first secret information embedded in the first steganographic image; The original carrier image is processed in a block manner in the block manner of the second carrier image, and the original carrier image is processed in the steganographic step of the second carrier image until the anti-overflow processing is completed, and then the second carrier image is subtracted from the processed original carrier image to obtain a plurality of second secret information embedded in the second steganographic image; Each first secret information and each second secret information is converted into a corresponding decimal number, and then each decimal number is converted into a corresponding binary number; all binary numbers are sequentially concatenated to obtain a complete secret information.

7. A block-based image processing apparatus for dual images, Features: An image steganography unit is included, which includes an image copying module, a first image steganography module, and a second image steganography module; The image copying module is used to copy the original carrier image into a first carrier image and a second carrier image; The first image steganography module includes: a first block submodule, used to block the first carrier image into at least one first reference pixel block and at least one first non-reference pixel block; wherein each first reference pixel block includes a plurality of first pixel points, and each first non-reference pixel block includes a plurality of first non-reference pixel points; A first pixel average value calculation submodule, used for summing and averaging the pixel values ​​of the first pixel points of each first reference pixel block to obtain a first pixel average value of each first reference pixel block; A first absolute difference calculation submodule is used to calculate the difference and absolute value of the first pixel average value in each first reference pixel block and the pixel value of each first non-reference pixel point in the adjacent first non-reference pixel block, so as to obtain the absolute difference between each first non-reference pixel point and the corresponding first pixel average value; A first embeddable point calculation submodule, configured to mark the first non-reference pixel point as a first embeddable point when the absolute difference is less than a preset threshold, and calculate the number of bits of embeddable secret information of the first embeddable point; A first image encryption submodule, used for intercepting secret information of corresponding bits from the secret information to be embedded according to the number of bits of embeddable secret information at each first embeddable point, and embedding the secret information into the corresponding first embeddable point, and obtaining a first encrypted image after all the first embeddable points are embedded with the secret information; The second image steganography module includes: a second block submodule, which is used to block the second carrier image into at least one second reference pixel block and at least one second non-reference pixel block; wherein each second reference pixel block includes a plurality of second pixel points, and each second non-reference pixel block includes a plurality of second non-reference pixel points; the second reference pixel block corresponds to the position of the first non-reference pixel block, and the second non-reference pixel block corresponds to the position of the first reference pixel block; A second pixel absolute difference calculation module, used for summing and averaging the pixel values ​​of the second pixel points of each second reference pixel block to obtain a second pixel average value of each second reference pixel block; A second absolute difference calculation submodule is used to calculate the difference and absolute value of the second pixel average value in each second reference pixel block and the pixel value of each second non-reference pixel point in the adjacent second non-reference pixel block, so as to obtain the absolute difference between each second non-reference pixel point and the corresponding second pixel average value; A second embeddable point calculation submodule, configured to mark the second non-reference pixel point as a second embeddable point when the absolute difference is less than a preset threshold, and calculate the number of embeddable secret information bits of the second embeddable point; The second image encryption submodule is used to intercept the corresponding number of bits of secret information from the secret information to be embedded according to the number of bits of embeddable secret information at each second embeddable point, and embed the secret information into the corresponding second embeddable point. After all the second embeddable points are embedded with secret information, a second encrypted image is obtained.

8. The block-based image processing apparatus of dual images according to claim 7, It is characterized in that Also included is an image restoration unit, which includes: an original carrier image recovery module, for extracting all first reference pixel blocks from the first secret image in a first carrier image block manner, and for extracting all second reference pixel blocks from the second secret image in a second carrier image block manner, and obtaining the original carrier image according to the extracted first reference pixel blocks and second reference pixel blocks; The first information extraction module is used to process the original carrier image in a block-by-block manner of the first carrier image, and process the original carrier image in a steganographic step of the first carrier image until the anti-overflow process is completed, and then the first carrier image is subtracted from the processed original carrier image to obtain a plurality of first secret information embedded in the first steganographic image; The second information extraction module is used to process the original carrier image in a block-by-block manner of the second carrier image, and process the original carrier image in a steganographic step of the second carrier image until the anti-overflow process is completed, and then the second carrier image is subtracted from the processed original carrier image to obtain a plurality of second secret information embedded in the second steganographic image; The information conversion module is used to convert each first secret information and each second secret information into a corresponding decimal number, and then convert each decimal number into a corresponding binary number; all binary numbers are sequentially spliced ​​to obtain complete secret information.

9. A computer-readable storage medium storing a computer program. It is characterized in that When the computer program is executed by a processor, the steps of the block-based image processing method of dual images according to any one of claims 1 to 6 are implemented.

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