CN112380551B - A dual-image-based reversible data hiding method and system - Google Patents

Abstract

The invention provides a reversible data hiding method and a reversible data hiding system based on double images, which are characterized in that a novel tortoise shell magic matrix is obtained by adding numerical values of '8' to element values of tortoise back points on the basis of the original tortoise shell magic matrix, the range of the element values in the matrix is expanded, the hidden quantity of hidden secret data of the matrix is increased, meanwhile, a novel reversible hiding algorithm is invented, the secret data are converted into hexadecimal numbers to be hidden in the novel tortoise shell magic matrix, and pairwise corresponding secret images are obtained; and in the stage of secret data extraction, a corresponding data extraction rule is formulated according to a novel reversible hiding algorithm to extract the secret data, and an original image is recovered. Compared with the traditional data hiding algorithm based on the image, the method has the advantage of ensuring the quality of the hidden image under the condition of higher storage capacity, so that the secret data can be hidden more safely.

Description

A dual-image-based reversible data hiding method and system

technical field

The invention relates to the technical field of image processing, in particular to a double-image-based reversible data hiding method and system.

Background technique

With the popularization of network technology, it is very convenient for people to communicate and exchange data with others on the network. However, due to the open nature of the network, the data transmitted on the network can easily be intercepted, tampered or destroyed by malicious personnel. Therefore, in order to improve the security of data exchange, a common solution is to encrypt the data to be transmitted. However, due to the complexity of the encryption algorithm, the encryption and decryption process takes a lot of time, and the encrypted data is a bunch of meaningless garbled things, which is more likely to arouse the suspicion of malicious personnel. Although malicious persons may not be able to directly decipher the data, they can destroy the data, resulting in the loss of data.

In addition to encryption technology, data hiding is also an effective data protection method. Data hiding algorithms can hide secret data into media, which can be images, video, audio, text, etc. After the data is hidden through the image, the image is not much different from the original image from the naked eye, so it is not easy to arouse the attacker's suspicion, so that the data transmission can be performed safely. After receiving the image with the secret information hidden, the receiver extracts the secret information according to the extraction algorithm.

According to whether the data receiver can recover the original image, data hiding is divided into reversible data hiding and irreversible data hiding. Generally, irreversible data hiding can hide more secret information. On the contrary, the amount of reversible data hiding is generally small. But the advantage of reversible data hiding is that the original image can be completely recovered.

The invention performs reversible data hiding based on double images. After the original image is hidden in the secret data, two images with the secret data are generated. The original image and the secret data cannot be extracted only through a single image containing the secret data. If and only when the two images containing the secret data are acquired by the receiver together, the cooperation of the two images can be completed. Reply with secret data and original image.

SUMMARY OF THE INVENTION

The present invention proposes a dual-image-based reversible data hiding method and system to solve the above-mentioned defects of the prior art.

In one aspect, the present invention proposes a dual-image-based reversible data hiding method, which includes the following steps:

S1: Construct a matrix whose abscissa and ordinate range is [0, 255], so that the values of adjacent elements in the same row in the matrix differ by 1, and increase in turn, and the values of even columns of adjacent two elements in the same column are higher than odd ones The value of the column is 2 more, the value of the odd-numbered column is 3 more than the value of the even-numbered column, and then the element value in the matrix is modulo 8 operation, so that the element value is between [0, 7]. The polygon covers the matrix to obtain a turtle shell magic matrix, wherein the points located at the edge of the hexagon in the matrix belong to the turtle edge points, and the points not located at the edge of the hexagon belong to the turtle back point, add the value "8" to the elements located at the turtle back point in the turtle shell magic matrix to obtain a new turtle shell magic matrix;

S2: Convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number;

S3: Take a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate (p,

且

从所述秘密信息中获取 一个十六进制数，记为v，根据所述点(p ,p)在所述新的龟壳魔术矩阵中的位置的不同确定 藏入范围，在所述藏入范围中找到使坐标对应的值为v的坐标(p1 ,p2) ，并根据移动规则 对所述坐标(p1 ,p2)存在冲突的点进行移动； p) , if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the point (p , p) in the new turtle shell magic matrix. Find the coordinates (p1, p2) with the value v corresponding to the coordinates in the input range, and move the points with conflicting coordinates (p1, p2) according to the moving rules;

S4: Assign p1 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to perform step S3 to obtain the first secret image, assign p2 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to perform step S3 to obtain the second secret image.

The above method expands the range of element values in the new turtle shell magic matrix by adding the value "8" to the element values of the turtle back points, thereby increasing the hidden secret data of the new turtle shell magic matrix. Using the new reversible hiding algorithm, the secret data can be well hidden and the original image can be restored with less changes to the original image. Compared with the traditional image-based secret data hiding algorithm, it has a higher hiding capacity At the same time, the advantages of the hidden image quality are guaranteed.

In a specific embodiment, the hiding range is determined according to the difference of the position of the point (p , p) in the new turtle shell magic matrix, and the specific steps include: making the vertical coordinate of the turtle back point larger The point is marked as the upper turtle back point, the point with the smaller ordinate in the turtle back point is marked as the lower turtle back point, and the ordinate in the turtle edge point is the smallest or the three points where the vertical coordinate is equal to the upper turtle back point. Each point is recorded as the upper turtle edge point, and the three points with the largest ordinate or the ordinate equal to the lower turtle edge point among the turtle edge points are recorded as the lower turtle edge point, if the pixel p belongs to the upper turtle edge point Or the upper turtle back point, construct a 4×5 block with the point whose coordinates are (p , p) in the new turtle shell magic matrix as the lower right corner, deduct the 4 elements in the upper right corner of the block, and use the remaining 16 elements to hide a hexadecimal number; if the pixel p belongs to the lower turtle edge point or the lower turtle back point, then construct a 4×5 block with (p ,p) as the upper left corner, deducting The 4 elements in the lower left corner of the block, use the remaining 16 elements to hide one of said hexadecimal numbers.

In a specific embodiment, the movement rules specifically include:

If the pixel p belongs to the upper turtle edge point or the upper turtle back point, move the element bf of the last column of the first row and the element bs of the last column of the second row in the hidden range according to the following rules:

If the pixel p belongs to the lower turtle edge point or the lower turtle back point, the element lf of the first column of the last row and the element ls of the first column of the second to last row in the hidden range are moved according to the following rules:

In a specific embodiment, in step S3, if the pixel p∈[0,2] or p∈[253,255], let p1=p2

=p, and directly execute step S4.

In a specific embodiment, it also includes the step of extracting the secret information in the image, which specifically includes:

A1: Execute the step S1 to obtain the new turtle shell magic matrix;

A2: Take out the p1 and p2 from the same position of the first secret image and the second secret image in turn, and define the difference d=p1-p2;

A3: Secret information extraction is performed according to the following rules:

(1) If d=0 and p1 and p2 belong to edge points, no secret information is hidden in the corresponding points in the first secret image and the second secret image; if d=0 and p1 and p2 do not belong to edge point, the hidden hexadecimal secret information v is the value of the midpoint (p1, p2) of the new turtle shell magic matrix;

(2) If d<0, the hidden hexadecimal secret information v is obtained according to the following rules:

(3) If d>0, the hidden hexadecimal secret information v is obtained according to the following rules:

where M(p1 , p2) represents the value of the midpoint (p1 , p2) of the new turtle shell magic matrix.

In a specific embodiment, it also includes the step of restoring the original picture, which is specifically included in the step A1-

Execute the following original image recovery algorithm after A3:

(1) If d=0, then the original pixel p=p1;

(2) If d<0, then p can be obtained in the following ways:

(3) If d>0, then p can be obtained in the following ways:

The pixel p at the corresponding position in the original image is restored, thereby restoring the original image.

According to a second aspect of the present invention, there is provided a computer-readable storage medium on which a computer program is stored, the computer program implementing the above method when executed by a computer processor.

According to a third aspect of the present invention, a dual-image-based reversible data hiding system is proposed, the system comprising:

New tortoise shell magic matrix building block: Configured to construct a matrix whose abscissa and ordinate range are [0,255], so that the values of adjacent elements in the same row in the matrix differ by 1, and increase in sequence, and adjacent elements in the same column are The value of the two elements of the even column is 2 more than the value of the odd column, and the value of the odd column is 3 more than the value of the even column, and then the element value in the matrix is modulo 8 operation, so that the element value is between [0,7] Finally, the matrix is covered with a plurality of connected and spliced hexagons to obtain a turtle shell magic matrix, wherein the points located at the edges of the hexagons in the matrix belong to the turtle edge points and are not located in the hexagons. point attribute at the edge of the polygon

At the turtle back point, add the value "8" to the elements located at the turtle back point in the turtle shell magic matrix to obtain a new turtle shell magic matrix;

Secret information preprocessing module: configured to convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number;

且

从所述秘密 信息中获取一个十六进制数，记为v，根据所述点(p ,p)在所述新的龟壳魔术矩阵中的位置 的不同确定藏入范围，在所述藏入范围中找到使坐标对应的值为v的坐标(p1 ,p2) ，并根 据移动规则对所述坐标(p1 ,p2)存在冲突的点进行移动； Secret information hiding module: configured to take out a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate (p,p), if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the point (p , p) in the new turtle shell magic matrix. Find the coordinates (p1, p2) with the value v corresponding to the coordinates in the input range, and move the points with conflicting coordinates (p1, p2) according to the moving rules;

Secret image generation module: configured to assign p1 to the position corresponding to the pixel p in the original image,

And traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to run the secret information hiding module to obtain the first secret image, and assign p2 to the corresponding pixel p in the original image. position, and traverse all pixels in the original image and all hexadecimal numbers in the secret information to run the secret information hiding module to obtain a second secret image; hiding range determination module: configured to hide the turtle In the back point, the point with the larger ordinate is recorded as the upper turtle back point, the point with the smaller vertical coordinate in the turtle back point is recorded as the lower turtle back point, and the ordinate in the turtle edge point is the smallest or the ordinate is the same as the described turtle back point. The three points that are equal to the upper turtle back point are recorded as the upper turtle edge point, and the three points whose vertical coordinate is the largest or the vertical coordinate is equal to the lower turtle back point in the turtle edge point are recorded as the lower turtle edge point. If the pixel p belongs to the upper turtle edge point or the upper turtle back point, a 4×5 block is constructed with the point whose coordinates are (p, p) in the new turtle shell magic matrix as the lower right corner, and the upper right corner of the block is deducted. 4 elements, use the remaining 16 elements to hide one of the hexadecimal numbers; if the pixel p belongs to the lower turtle edge point or the lower turtle back point, the point whose coordinates are (p, p) is A 4x5 block is constructed in the upper left corner, the 4 elements in the lower left corner of the block are deducted, and the remaining 16 elements are used to hide a said hexadecimal number.

On the basis of the original turtle shell magic matrix, the invention constructs a new turtle shell magic matrix by adding the value "8" to the element values of the turtle back points, and expands the range of element values in the turtle shell magic matrix. This increases the amount of hidden secret data hidden by the new turtle shell magic matrix, and at the same time, a new reversible hiding algorithm is invented, which converts the secret data into hexadecimal numbers and hides them in the new turtle shell magic matrix. The corresponding secret image; in the stage of secret data extraction, the corresponding data extraction rules are formulated according to the new reversible hiding algorithm to extract the secret data and restore the original image. The invention can hide the secret data well and restore the original image under the condition of less changes to the original image. The advantages of image quality make secret data hidden more securely.

Description of drawings

The accompanying drawings are included to provide a further understanding of the embodiments and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments and together with the description serve to explain the principles of the invention. Other embodiments and many of the intended advantages of the embodiments will be readily recognized as they become better understood by reference to the following detailed description. Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

1 is a flowchart of a dual-image-based reversible data hiding method according to an embodiment of the present invention;

Fig. 2 is the new turtle shell magic matrix of a specific embodiment of the present invention;

3 is a schematic diagram of a single turtle shell structure in the turtle shell magic matrix of a specific embodiment of the present invention;

4 is a schematic diagram of classification of two secret information hiding methods based on 4×5 blocks according to an embodiment of the present invention;

Fig. 5 is the schematic diagram that utilizes the new turtle shell magic matrix to carry out data hiding of a specific embodiment of the present invention;

6 is a schematic diagram of a movement rule of a conflict point according to an embodiment of the present invention;

7 is a schematic diagram of a possible value range of the difference d according to an embodiment of the present invention;

8 is a frame diagram of a dual-image-based reversible data hiding system according to an embodiment of the present invention;

FIG. 9 is a comparison diagram of the maximum reserves value of different methods of a specific embodiment of the present invention;

FIG. 10 is a comparison diagram of image quality values of different methods in the case of the maximum storage amount according to a specific embodiment of the present invention.

Detailed ways

The present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the related invention, but not to limit the invention. In addition, it should be noted that, for the convenience of description, only the parts related to the related invention are shown in the drawings.

It should be noted that the embodiments in the present application and the features of the embodiments may be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the accompanying drawings and in conjunction with the embodiments.

A double-image-based reversible data hiding method according to an embodiment of the present invention, FIG. 1 shows a flowchart of a double-image-based reversible data hiding method according to an embodiment of the present invention. As shown in Figure 1, the method includes the following steps:

S101: Construct a matrix whose abscissa and ordinate are in the range of [0, 255], so that the values of adjacent elements in the same row in the matrix differ by 1, and increase in sequence, and the values of even columns of two adjacent elements in the same column are higher than odd ones The value of the column is 2 more, the value of the odd-numbered column is 3 more than the value of the even-numbered column, and then the element value in the matrix is modulo 8 operation, so that the element value is between [0, 7]. The polygon overlays the matrix, resulting in the turtle shell magic matrix. The feature of this matrix is that its horizontal and vertical coordinates are in the range of [0, 255], which corresponds to the value range of the pixel value of the grayscale image; the values of two adjacent elements in the same row in the matrix are incremented by 1 from left to right. , the value of two adjacent elements in the same column even column is 2 more than the value of odd column, the value of odd column is 3 more than the value of even column, the element value in the final matrix needs to be modulo 8 operation to ensure that the element value is in between [0, 7].

In a specific embodiment, the points located at the edge of the hexagon in the turtle shell magic matrix belong to the turtle edge points, the points not located at the edge of the hexagon belong to the turtle back points, and the turtle back The larger ordinate in the point is the upper turtle back point, the smaller ordinate in the turtle back point is the lower turtle back point, and the ordinate in the turtle edge point is the smallest or the ordinate is equal to the upper turtle back point The three points are the upper turtle edge points, and the three points with the largest ordinate or the ordinate equal to the lower turtle back point in the turtle edge points are the lower turtle edge points.

3 shows a schematic diagram of a single turtle shell structure in a turtle shell magic matrix according to a specific embodiment of the present invention, wherein points (311, 312, 314) are the lower turtle edge points, and point (313) is the lower turtle back point , point (321, 322, 324) is the upper turtle edge point, and point (323) is the upper turtle back point.

According to the definition of the points in the turtle shell magic matrix shown in Figure 3, add the value "8" to the elements located at the turtle back points (313, 323) in the turtle shell magic matrix to obtain a new turtle shell magic matrix as shown in the figure 2, where pi and pi+1 are the abscissa and ordinate of the new turtle shell magic matrix, respectively. In this embodiment, the abscissa and ordinate are taken as p1 and p2.

S102: Convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number.

且

从所述秘密信息中 获取一个十六进制数，记为v，根据所述点(p ,p)在所述新的龟壳魔术矩阵中的位置的不同 确定藏入范围，在所述藏入范围中找到使坐标对应的值为v的坐标(p1 ,p2) ，并根据移动 规则对所述坐标(p1 ,p2) 存在冲突的点进行移动。 S103: Take out a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate (p,p), if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the point (p , p) in the new turtle shell magic matrix. Find the coordinates (p1 , p2 ) with the value v corresponding to the coordinates in the input range, and move the points with conflicting coordinates (p1 , p2 ) according to the moving rules.

In a specific embodiment, the hiding range is determined according to the difference of the position of the point (p, p) in the new turtle shell magic matrix, and the specific steps include: if the pixel p belongs to the upper turtle edge point ( 321, 322, 324) or the upper turtle back point (323), then a 4×5 block is constructed with the point whose coordinates are (p , p) in the new turtle shell magic matrix as the lower right corner, and the upper right corner of the block is deducted 4 elements of the corner, use the remaining 16 elements to hide one of the hexadecimal numbers; if the pixel p belongs to the lower turtle edge point (311, 312, 314) or the lower turtle back point (313), Then construct a 4×5 block with (p ,p) as the upper left corner, deduct the 4 elements in the lower left corner of the block, and use the remaining 16 elements to hide a hexadecimal number.

According to the above method, draw a 4×5 block arbitrarily in the new turtle shell magic matrix shown in Figure 2 (as shown in the box in Figure 2), then the elements in it must contain 0-15, and the upper right corner must be and the 4 elements in the lower left corner are repeated, as indicated by the dashed circles in Figure 2. Therefore, after deducting 4 repeated elements, the remaining 16 element values must belong to [0, 15], and the drawn 4×5 block has two situations as shown in Figure 4:

Fig. 4 is a schematic diagram showing the classification of two secret information hiding methods based on 4×5 blocks according to an embodiment of the present invention, one is a group of 4 elements in the upper right corner (marked as t), and the remaining 16 The elements are a group (marked as t1), as shown in Figure 401, if the pixel p belongs to the upper turtle edge point (321, 322, 324) or the upper turtle back point (323), use the point in t1 to hide Enter a hexadecimal number. The other type is that there are 4 elements in the lower left corner as a group (marked as b), and the remaining 16 elements are grouped as a group (marked as b1), as shown in Figure 402, if the pixel p belongs to the lower turtle edge point ( 311, 312, 314) or the lower turtle back point (313), use the point in b1 to hide the hexadecimal number.

FIG. 5 shows a schematic diagram of data hiding using a new turtle shell magic matrix according to a specific embodiment of the present invention, such as points (4, 4), (6, 6) and (8, 8 in FIG. 5 ) ) belongs to the upper turtle edge point or upper turtle back point, then a 4×5 block is constructed with (p ,p) as the lower right corner element, and the 4 elements in the upper right corner of the block are deducted, that is, 16 elements in t1 are used to Hide a hexadecimal number; for example, the points (3, 3), (5, 5) and (7, 7) in Figure 5 belong to the lower turtle edge point or lower turtle back point, then use (p, p ) constructs a 4×5 block for the upper left corner, deducting the 4 elements in the lower left corner of the block, that is, using the 16 elements in b1 to hide a hexadecimal number.

In a specific embodiment, when different p hides the same number v, a position conflict problem may occur. For example, when both positions (4, 4) and (6, 6) are hidden with the value v=1, the elements at these two positions will be moved to (2, 6), which makes it impossible to restore the original pixel correctly. Therefore, in the present invention, a rule is set to move these points that may cause confusion.

6 is a schematic diagram of a movement rule of a conflict point according to an embodiment of the present invention, and the movement rule specifically includes:

As shown in Figure 601, if the pixel p belongs to the upper turtle edge point (321, 322, 324) or the upper turtle back point (323), the elements bf and the last column of the first row and the last column in the hidden range are The element bs of the last column of the second row is moved according to the following rules:

As shown in Figure 602, if the pixel p belongs to the lower turtle edge point (311, 312, 314) or the lower turtle back point (313), the elements lf and the first column of the last row in the hidden range are The element ls in the first column of the penultimate row moves according to the following rules:

In a specific embodiment, in step S3, if the pixel is p∈[0,2] or p∈[253,255], let p1=p2=p, and directly execute step S4.

S104: Assign p1 to the position corresponding to the pixel p in the original image, and traverse the original image

Perform step S3 for all pixels in the original image and all hexadecimal numbers in the secret information to obtain a first secret image, assign p2 to the position corresponding to the pixel p in the original image, and traverse the original image. Step S3 is performed for all pixels of and all hexadecimal numbers in the secret information to obtain a second secret image.

In a specific embodiment, it also includes the step of extracting the secret information in the image, which specifically includes:

A1: Execute the step S1 to obtain the new turtle shell magic matrix;

A2: Take out the p1 and p2 from the same position of the first secret image and the second secret image in turn, and define the difference d=p1-p2, where the possible value range of the difference d is shown in Figure 7 , it can be seen that the value range of d is [-8, 8]. If d > 0, it means that the original pixel p belongs to the lower turtle edge point or the lower turtle back point; if d < 0, it means that the original pixel p belongs to the upper turtle edge point or upper turtle back point;

A3: Secret information extraction is performed according to the following rules:

(1) If d=0 and p1 and p2 belong to edge points, no secret information is hidden in the corresponding points in the first secret image and the second secret image; if d=0 and p1 and p2 do not belong to edge point, the hidden hexadecimal secret information v is the value of the midpoint (p1, p2) of the new turtle shell magic matrix;

(2) If d<0, the hidden hexadecimal secret information v is obtained according to the following rules:

(3) If d>0, the hidden hexadecimal secret information v is obtained according to the following rules:

where M(p1 , p2) represents the value of the midpoint (p1 , p2) of the new turtle shell magic matrix.

In a specific embodiment, it also includes the step of restoring the original picture, which is specifically included in the step A1-

Execute the following original image recovery algorithm after A3:

(1) If d=0, then the original pixel p=p1;

(2) If d<0, then p can be obtained in the following ways:

(3) If d>0, then p can be obtained in the following ways:

The pixel p at the corresponding position in the original image is restored, thereby restoring the original image.

FIG. 8 shows a frame diagram of a dual-image-based reversible data hiding system according to an embodiment of the present invention. The system includes a new turtle shell magic matrix building module 801 , a secret information preprocessing module 802 , a secret information hiding module 803 and a secret image generating module 804 .

且

从所述秘密信息中获取一个十六进制数，记 为v，根据所述点(p ,p)在所述新的龟壳魔术矩阵中的位置的不同确定藏入范围，在所述藏 入范围中找到使坐标对应的值为v的坐标(p1 ,p2) ，并根据移动规则对所述坐标(p1 ,p2) 存在冲突的点进行移动；秘密图像生成模块804被配置用于将p1赋值给所述原始图像中所 述像素p对应的位置，并遍历所述原始图像中的所有像素和所述秘密信息中的所有十六进 制数运行秘密信息隐藏模块，得到第一秘密图像，将p2赋值给所述原始图像中所述像素p对 应的位置，并遍历所述原始图像中的所有像素和所述秘密信息中的所有十六进制数运行秘 密信息隐藏模块，得到第二秘密图像。 In a specific embodiment, the new turtle shell magic matrix construction module 801 is configured to construct a matrix whose abscissa and ordinate are in the range of [0, 255], so that the values of adjacent elements in the same row in the matrix differ by 1, and Incrementing in turn, the value of the two adjacent elements in the same column even column is 2 more than the value of the odd column, the value of the odd column is 3 more than the value of the even column, and then the element value in the matrix is modulo 8 operation, so that the element The value is between [0, 7], and finally cover the matrix with a plurality of continuous hexagons to obtain the turtle shell magic matrix. Add the value "8" to obtain a new turtle shell magic matrix; the secret information preprocessing module 802 is configured to convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number The secret information hiding module 803 is configured to extract a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate (p,p), if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the point (p , p) in the new turtle shell magic matrix. find the coordinates (p1, p2) with the value v corresponding to the coordinates in the range, and move the points where the coordinates (p1, p2) conflict according to the moving rules; the secret image generation module 804 is configured to convert p1 assigning a value to the position corresponding to the pixel p in the original image, and traversing all the pixels in the original image and all the hexadecimal numbers in the secret information to run the secret information hiding module to obtain the first secret image, Assign p2 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to run the secret information hiding module to obtain the second secret image.

Through the joint action of the above modules, the element value of the turtle back point is firstly added with the value "8", which expands the range of element values in the new turtle shell magic matrix, thereby increasing the hidden secret data of the new turtle shell magic matrix. It can hide the secret data well and restore the original image under the condition of less changes to the original image. Compared with the traditional image-based secret data hiding algorithm, it has more storage capacity. In higher cases, the advantage of the hidden image quality is guaranteed at the same time.

In order to verify the reliability and beneficial effects of the present invention, the inventors conducted a series of experiments, using the storage capacity (ER) and the image quality (PSNR) after hiding secret data to evaluate the algorithm of the present invention and other traditional algorithms in the field. The superiority of the ratio, the larger the value of the two, the better the algorithm.

Among them, the unit of measurement of ER is bpp, that is, the number of bits that can be hidden in a single pixel, and PSNR refers to the peak signal-to-noise ratio of the image, and the unit is dB, which is calculated by the following formula:

Where H and W represent the width and height of the image, m and m1 represent the original image and the image containing the secret data, and the subscript (i,j) represents the position of the i-th row and the j-th column.

In this embodiment, the dual-image reversible data hiding method based on Sudoku matrix [1], the EMD matrix-based dual-image reversible data hiding method [2], and the original turtle-shell matrix-based dual-image reversible data hiding method [ 3] and base

The real-time double-image reversible data hiding method [4] based on turtle shell matrix is compared with the method of the present invention.

Fig. 9 shows a comparison chart of the maximum reserves value of different methods of a specific embodiment of the present invention. It can be seen that, in addition to method [1], the method proposed by the present invention can obtain higher than other methods. holding capacity.

FIG. 10 is a comparison diagram of image quality values of different methods in the case of the maximum storage capacity of a specific embodiment of the present invention, and FIG. 10 is a comparison result of PSNR values of the present invention and other methods in the case of the maximum ER value. It can be seen that although the method [1] and the method of the present invention obtain the same high ER value, the method of the present invention can maintain higher image quality, and compared with the methods [2, 3, 4], although the method of the present invention The method has no advantage in PSNR, but the method of the present invention can obtain higher reserves than these methods.

Embodiments of the present invention also relate to a computer-readable storage medium having stored thereon a computer program that, when executed by a computer processor, implements the above method. The computer program contains program code for carrying out the method shown in the flowchart. It should be noted that the computer-readable medium of the present application may be a computer-readable signal medium or a computer-readable medium, or any combination of the above two.

The invention provides a double-image-based reversible data hiding method and system, which includes obtaining a new turtle shell by adding "8" to the element values of the turtle back points on the basis of the original turtle shell magic matrix. Magic matrix, which expands the range of element values in the matrix, increases the amount of hidden secret data hidden in the matrix, and at the same time invents a new type of reversible hiding algorithm, which converts the secret data into hexadecimal numbers and hides them in a new turtle shell magic In the matrix, the corresponding secret images are obtained; in the stage of secret data extraction, the corresponding data extraction rules are formulated according to the new reversible hiding algorithm to extract the secret data and restore the original image. The invention can hide secret data well and restore the original image under the condition of less changes to the original image. Compared with the traditional image-based data hiding algorithm, the invention can guarantee the hidden image at the same time under the condition of high storage capacity. The advantage of quality, so that secret data can be hidden more securely.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above technical features, and should also cover the above technical features or Other technical solutions formed by any combination of its equivalent features. For example, a technical solution is formed by replacing the above features with the technical features disclosed in this application (but not limited to) with similar functions.

Claims (7)

1. a reversible data hiding method based on double image, is characterized in that, comprises the following steps: S1: Construct a matrix whose abscissa and ordinate range is [0, 255], so that the values of adjacent elements in the same row in the matrix differ by 1, and increase in turn, and the values of even columns of adjacent two elements in the same column are higher than odd ones. The value of the column is 2 more, the value of the odd column is 3 more than the value of the even column, and then the element value in the matrix is modulo 8 operation, so that the element value is between [0, 7]. The polygon covers the matrix to obtain a turtle shell magic matrix, wherein the points located at the edge of the hexagon in the matrix belong to the turtle edge points, and the points not located at the edge of the hexagon belong to the turtle back point, add the value "8" to the elements located at the turtle back point in the turtle shell magic matrix to obtain a new turtle shell magic matrix; S2: Convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number; S3: Take out a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate point (p, p), if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the coordinate point (p, p) in the new turtle shell magic matrix. Find the coordinates (p1, p2) with the value v corresponding to the coordinates in the hiding range, and move the points with conflicting coordinates (p1, p2) according to the moving rules; S4: Assign p1 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to perform step S3 to obtain the first secret image, assign p2 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to perform step S3 to obtain the second secret image; Wherein, according to the different positions of the coordinate points (p, p) in the new turtle shell magic matrix to determine the hiding range, the specific steps include: It is recorded as the upper turtle back point, the point with the smaller ordinate in the turtle back point is recorded as the lower turtle back point, and the three points where the ordinate is the smallest or the ordinate is equal to the upper turtle back point in the turtle edge point It is recorded as the upper turtle edge point, and the three points whose ordinate is the largest or the ordinate is equal to the lower turtle back point in the turtle edge point are recorded as the lower turtle edge point, if the pixel p belongs to the upper turtle edge point or the upper turtle edge point. Turtle back point, construct a 4×5 block with the point whose coordinates are (p, p) in the new turtle shell magic matrix as the lower right corner, deduct the 4 elements in the upper right corner of the block, and use the remaining 16 element to hide a hexadecimal number; if the pixel p belongs to the lower turtle edge point or the lower turtle back point, a 4×5 block is constructed with the point whose coordinates are (p, p) as the upper left corner , subtract the 4 elements in the lower left corner of the block, and use the remaining 16 elements to hide one of said hexadecimal numbers. 2. The method according to claim 1, wherein the movement rule specifically comprises: If the pixel p belongs to the upper turtle edge point or the upper turtle back point, move the element bf of the last column of the first row and the element bs of the last column of the second row in the hidden range according to the following rules:

If the pixel p belongs to the lower turtle edge point or the lower turtle back point, the element lf of the first column of the last row and the element ls of the first column of the second to last row in the hidden range are moved according to the following rules:

. 3. The method according to claim 1, wherein in the step S3, if the pixel p∈[0,2] or p ∈ [253, 255], let p1=p2=p, and directly execute the step S4. 4. The method according to claim 1, further comprising the step of extracting the secret information in the image, specifically comprising: A1: Execute the step S1 to obtain the new turtle shell magic matrix; A2: Take out the p1 and p2 from the same position of the first secret image and the second secret image in sequence, and define the difference d=p1-p2; A3: Secret information extraction is performed according to the following rules: (1) If d=0 and p1 and p2 belong to edge points, no secret information is hidden in the corresponding points in the first secret image and the second secret image; if d=0 and p1 and p2 do not belong to edge point, the hidden hexadecimal secret information v is the value of the midpoint (p1, p2) of the new turtle shell magic matrix; (2) If d<0, the hidden secret information v in hexadecimal is obtained according to the following rules:

(3) If d>0, the hidden hexadecimal secret information v is obtained according to the following rules:

Wherein M(p1, p2) represents the value of the midpoint (p1, p2) of the new turtle shell magic matrix. 5. The method according to claim 4, further comprising the step of restoring the original picture, specifically comprising executing the following original picture restoration algorithm after the steps A1-A3: (1) If d=0, then the original pixel p=p1; (2) If d<0, then p is obtained in the following way:

(3) If d>0, then p is obtained in the following ways:

The pixel p at the corresponding position in the original image is restored, thereby restoring the original image. 6. A computer-readable storage medium on which a computer program is stored, characterized in that, when the computer program is executed by a computer processor, the method according to any one of claims 1 to 5 is implemented. 7. A reversible data hiding system based on double image, is characterized in that, comprises: New tortoise shell magic matrix building block: Configured to construct a matrix with abscissa and ordinate range of [0, 255], so that the values of adjacent elements in the same row in the matrix differ by 1, and increase in sequence, and adjacent elements in the same column are adjacent to each other. The value of the even column of the two elements is 2 more than the value of the odd column, and the value of the odd column is 3 more than the value of the even column, and then the element value in the matrix is modulo 8 operation, so that the element value is between [0, 7] Finally, the matrix is covered with a plurality of connected and spliced hexagons to obtain a turtle shell magic matrix, wherein the points located at the edges of the hexagons in the matrix belong to the turtle edge points and are not located in the hexagons. The point at the edge of the polygon belongs to the turtle back point, and each element located at the turtle back point in the turtle shell magic matrix is added with a value of "8" to obtain a new turtle shell magic matrix; Secret information preprocessing module: configured to convert the secret information to be hidden into a string of binary numbers, and then convert every 4 binary numbers into a hexadecimal number; Secret information hiding module: configured to take out a pixel p(p∈[0,255]) from the original image, and expand the pixel p into a coordinate point (p,p), if the pixel

and

Obtain a hexadecimal number from the secret information, denoted as v, and determine the hiding range according to the position of the coordinate point (p, p) in the new turtle shell magic matrix. Find the coordinates (p1, p2) with the value v corresponding to the coordinates in the hiding range, and move the points with conflicting coordinates (p1, p2) according to the moving rules; Secret image generation module: configured to assign p1 to the position corresponding to the pixel p in the original image, and traverse all the pixels in the original image and all the hexadecimal numbers in the secret information to run the secret The information hiding module obtains the first secret image, assigns p2 to the position corresponding to the pixel p in the original image, and traverses all pixels in the original image and all hexadecimal numbers in the secret information Run the secret information hiding module to obtain the second secret image; The hiding range determination module is configured to record the point with a larger ordinate in the turtle back point as the upper turtle back point, and the point with the smaller vertical coordinate in the turtle back point as the lower turtle back point. Among the turtle edge points, the three points whose ordinate is the smallest or whose ordinate is equal to the upper turtle back point are recorded as the upper turtle edge point, and the one whose ordinate is the largest or whose ordinate is equal to the lower turtle edge point in the turtle edge point. The three points are recorded as the lower turtle edge point. If the pixel p belongs to the upper turtle edge point or the upper turtle back point, the point with the coordinates (p, p) in the new turtle shell magic matrix is used as the lower right corner to construct. A 4×5 block, deduct the 4 elements in the upper right corner of the block, and use the remaining 16 elements to hide a hexadecimal number; if the pixel p belongs to the lower turtle edge point or the lower turtle back point , then construct a 4×5 block with the point whose coordinates are (p, p) as the upper left corner, deduct the 4 elements in the lower left corner of the block, and use the remaining 16 elements to hide a hexadecimal number .

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