CN-115861015-B - Robust reversible watermark embedding method and extraction method based on pseudo Zernike moment

CN115861015BCN 115861015 BCN115861015 BCN 115861015BCN-115861015-B

Abstract

The invention relates to the technical field of digital watermarking and discloses a robust reversible watermarking embedding method and an extraction method based on pseudo Zernike moments, wherein the method comprises the steps of calculating pseudo Zernike moments of an original image, performing self-adaptive normalization operation on the pseudo Zernike moments of different orders, performing pseudo Zernike inverse transformation on a difference value between the pseudo Zernike moments calculated by the image with the robust watermarking and the pseudo Zernike moment for reconstructing the image with the robust watermarking, and performing watermarking embedding by adopting a quantization watermarking method; extracting watermark information of an image which is not attacked and recovering the original image when the image is not attacked, and extracting watermark information of the attacked image when the image is attacked. The invention gives the watermark strength of different sizes of the pseudo Zernike moments with different orders, so that the robust reversible image has stronger robustness to geometric attack and conventional processing. And compensating the obtained error image into an image with a robust watermark, and further reducing the distortion information amount so as to realize large-capacity watermark embedding.

Inventors

TANG YICHAO
WANG CHUNTAO
BIAN SHAN

Assignees

华南农业大学

Dates

Publication Date: 20260505
Application Date: 20220627

Claims (9)

1. The robust reversible watermark embedding method based on the pseudo Zernike moment is characterized by comprising the following steps of: s1, acquiring an original image I; s2, calculating n-order m-weight pseudo Zernike moment of original image I ; S3, for the pseudo Zernike moment Performing self-adaptive normalization operation to obtain normalized pseudo Zernike moment ; S4, for normalized pseudo Zernike moments Embedding the quantized watermark to obtain normalized pseudo Zernike moment with robust watermark Quantization distortion Wherein, the method comprises the steps of, Representing robust watermark information; s5, normalizing the pseudo Zernike moment with the robust watermark Performing self-adaptive normalized inverse operation to obtain pseudo Zernike moment with robust watermark ; S6, for the pseudo Zernike moment with the robust watermark Performing pseudo Zernike inverse transformation and rounding operations to obtain an image with a robust watermark ; S7, calculating an image with a robust watermark Pseudo Zernike moments of (A) Then calculate pseudo Zernike moments And pseudo Zernike moments Is subjected to pseudo Zernike inverse transformation and rounding operation to obtain an error image Error image is processed And images with robust watermarks Performing superposition processing to obtain a superposition image ; S8, for the superimposed image Carrying out a dewatering operation to obtain a dewatering superimposed image Comprising: computing superimposed images Pseudo Zernike moments of (A) ; For the pseudo Zernike moment Performing self-adaptive normalization operation to obtain normalized pseudo Zernike moment ; By extracting the normalized pseudo Zernike moments Is of (2) quantization distortion Obtaining normalized pseudo Zernike moment for removing robust watermark For the normalized pseudo Zernike moments Performing self-adaptive normalized inverse operation to obtain pseudo Zernike moment The calculation formula is as follows: calculating pseudo Zernike moments And pseudo Zernike moments Performing pseudo Zernike inverse transformation and rounding operation on the difference value, and combining the rounding operation result with the superimposed image Performing superposition processing to obtain a de-watermark superposition image The calculation formula is as follows: ; s9, calculating an original image I and a water stamp superposition image Rounding distortion between ; S10, distorting the quantization Said rounding distortion Superimposed images Least significant bits of the first N pixels of (b) are embedded into an image with a robust watermark In the method, an intermediate image containing a robust watermark and a reversible watermark is obtained Wherein, the method comprises the steps of, Is reversible watermark information; s11, generating an intermediate image Hash value of (a) And the hash value is used for Replacing intermediate images Least significant bits of the first N pixels of (b) to obtain a robust reversible watermark image 。
2. The robust reversible watermark embedding method based on pseudo Zernike moments according to claim 1, characterized in that in S2, the n-order m-weighted pseudo Zernike moments of the original image I are calculated The method comprises the following specific steps of: Taking the center of an original image I with the size of B multiplied by B as a circle center, B as a positive integer, making an inscribed circle of the original image I, and constructing a pseudo Zernike base based on the inscribed circle Taking the inscribed circle as a unit circle, and according to the pseudo Zernike base Calculating n-order m-weighted pseudo Zernike moments of pixels in a unit circle The specific expression is as follows: Wherein the pseudo Zernike basis Is a set of perfect orthogonal bases on a unit circle, Representing the s-th abscissa of the original image I, Representing the t-th ordinate of the original image I, Represents the abscissa step size of the unit circle in the original image I, Representing the ordinate step of a unit circle in the original image I, Representing pixels within a unit circle.
3. A method of robust reversible watermark embedding based on pseudo Zernike moments according to claim 1, characterized in that in S3 the pseudo Zernike moments are registered Performing self-adaptive normalization operation to obtain normalized pseudo Zernike moment The specific expression is as follows: Wherein, the To embed the order of the pseudo Zernike moments of the ith watermark bit, For the repetition number of the pseudo Zernike moment of the embedded ith watermark bit, j is the bit value corresponding to the ith watermark bit, Pseudo Zernike moment, which is 0 th order 0 heavy, N is the upper limit of the order N, For the adaptive normalization of the weights, For the initial value of the adaptive normalization weights, Is a global parameter for adjusting the watermark strength.
4. The robust reversible watermark embedding method based on pseudo Zernike moments according to claim 1, characterized in that in S4, the pseudo Zernike moments are normalized Embedding the quantized watermark to obtain normalized pseudo Zernike moment with robust watermark Quantization distortion The specific expression is as follows: Wherein, the Representing constraints as Is used to determine the jitter value of (1), For the quantization step size, Representation of To the fraction between its nearest integers.
5. The method of claim 1, wherein in S6, the pseudo Zernike moment with robust watermark is embedded Performing pseudo Zernike inverse transformation and rounding operations to obtain an image with a robust watermark The specific expression is as follows: where L represents the length of the robust watermark information.
6. The robust reversible watermark embedding method based on pseudo Zernike moments according to claim 1, characterized in that in S7, the pseudo Zernike moment is calculated And images with robust watermarks Pseudo Zernike moments of (A) Is subjected to pseudo Zernike inverse transformation and rounding operation to obtain an error image The specific expression is as follows: The error image is to be displayed And images with robust watermarks Performing superposition processing to obtain a superposition image The specific expression is as follows: 。
7. the robust reversible watermark extraction method based on pseudo Zernike moment is characterized by comprising the following steps: Obtaining robust reversible watermark images Superimposed images The robust reversible watermark image Superimposed images A robust reversible watermark embedding method based on pseudo Zernike moment according to any one of claims 1-6 is adopted for generation; extracting the robust reversible watermark image Least significant bits of the first S pixels of (i.e. intermediate image) Hash value of (a) And robust reversible watermarking image using reversible watermarking method Restoring to intermediate image ; Extracting superimposed images Least significant bits of the first S pixels of (2), and replacing the extraction result with the intermediate image After the least significant bits of the first S pixels, an intermediate image is generated Hash value of (a) ; When hash value Equal to the hash value Judging robust reversible watermark image Unaddressed and intermediate image Is not attacked and performs the following steps: Extracting intermediate images that are not attacked Watermark information of (2); for intermediate images not attacked Performing a recovery operation to recover the intermediate image which is not attacked Restoring to the original image I; When hash value Not equal to hash value Judging robust reversible watermark image Attacked and intermediate image Under attack, the following steps are performed: extracting attacked intermediate images Watermark information of (a) is provided.
8. The robust and reversible watermark extraction method based on pseudo Zernike moments according to claim 7, characterized in that, When hash value Equal to the hash value When extracting the intermediate image not attacked The step of watermark information of (a) comprises: Extracting intermediate images that are not attacked Least significant bits of the first S pixels of (b), quantization distortion Rounding distortion And using a reversible watermarking method to render an intermediate image that is not attacked Restoring to an image with a robust watermark ; Computing an image with a robust watermark Pseudo Zernike moments of (A) And for the pseudo Zernike moment Performing self-adaptive normalization operation to obtain normalized pseudo Zernike moment ; From normalized pseudo Zernike moments The quantization watermarking method is used for extracting the robust watermarking information w 1 , and the expression is as follows: Wherein, the To embed the order of the pseudo Zernike moments of the ith watermark bit, For the repetition number of the pseudo Zernike moment of the i-th watermark bit, i is the i-th watermark bit, j is the bit value corresponding to the i-th watermark bit, Representing constraints as Is used to determine the jitter value of (1), Is the quantization step length; the pair of intermediate images not attacked Performing a recovery operation to recover the intermediate image which is not attacked The step of restoring to the original image I comprises: According to the quantization distortion The normalized pseudo Zernike moment Conversion to pseudo Zernike moments The expression is as follows: for the pseudo Zernike moment Inverse operation with adaptive normalization Pseudo Zernike moment ; For the pseudo Zernike moment Performing pseudo Zernike inverse transformation and rounding operation to obtain a water mark superimposed image The expression is as follows: Wherein L represents the length of the robust watermark information; According to rounding distortion Superimposed image of water stamp Is converted into an original image I, and the expression is as follows: 。
9. The robust and reversible watermark extraction method based on pseudo Zernike moments according to claim 7, characterized in that, When hash value Not equal to hash value When extracting the attacked intermediate image The step of watermark information of (a) comprises: computing an attacked intermediate image Pseudo Zernike moments of (A) For the pseudo Zernike moment Performing self-adaptive normalization operation to obtain normalized pseudo Zernike moment ; For normalized pseudo Zernike moments Performing quantization watermark extraction operation to obtain an attacked intermediate image Watermark information of (a) The expression is as follows: Wherein, the To embed the order of the pseudo Zernike moments of the ith watermark bit, For the repetition number of the pseudo Zernike moment of the i-th watermark bit, i is the i-th watermark bit, j is the bit value corresponding to the i-th watermark bit, Representing constraints as Is used to determine the jitter value of (1), For quantization step sizes.

Description

Robust reversible watermark embedding method and extraction method based on pseudo Zernike moment Technical Field The invention relates to the technical field of digital watermarking, in particular to a robust reversible watermarking embedding method and an extraction method based on pseudo Zernike moment. Background The digital watermarking technology plays a role in identification by embedding digital information such as image identification, numbers, characters, serial numbers and the like into digital media. In recent years, robustness research on image digital watermarks has been greatly advanced, but there are still great difficulties in geometrical attacks such as rotation, scaling, translation and the like. The robust reversible watermark has the characteristics that when the carrier image is not attacked, the embedded watermark information can be correctly extracted and the carrier image can be completely recovered, and when the carrier image is attacked to a certain extent, the watermark information can still be correctly extracted without damage. The existing reversible robust watermarking method comprises the steps of carrying out quantization watermarking embedding on an image based on Zernike moments of the image through calculation of the Zernike moments of the image, judging whether the image is attacked or not through distortion information generated in the quantization watermarking embedding process, extracting watermarking information by using the Zernike moments of the image and recovering an original image when the image is judged not to be attacked, calculating the Zernike moments of the image with watermarking information after the image is attacked when the image is judged to be attacked, and extracting watermarking information by using the Zernike moments of the image with watermarking information. However, the above method does not consider the fact that the watermark strength required by the Zernike moments of different orders is different in the watermark embedding process, so that the distortion information is too large, and the method does not compensate the distortion information generated in the Zernike forward and backward conversion process, so that the amount of the distortion information for reversible watermark embedding is further increased, and the defects of low robustness and incapability of meeting the requirement of large-capacity watermark embedding are caused. Disclosure of Invention The invention provides a robust reversible watermark embedding method and an extraction method based on pseudo Zernike moment, which are used for overcoming the defects that the robustness is low and large-capacity watermark embedding cannot be met in the prior art. In order to solve the technical problems, the technical scheme of the invention is as follows: in a first aspect, the present invention proposes a robust reversible watermark embedding method based on pseudo Zernike moments, comprising the steps of: s1, acquiring an original image I. S2, calculating n-order m-weight pseudo Zernike moment of original image I。 S3, for the pseudo Zernike momentPerforming self-adaptive normalization operation to obtain normalized pseudo Zernike moment。 S4, for normalized pseudo Zernike momentsEmbedding the quantized watermark to obtain normalized pseudo Zernike moment with robust watermarkQuantization distortion. Wherein, the Representing robust watermark information. S5, normalizing the pseudo Zernike moment with the robust watermarkPerforming self-adaptive normalized inverse operation to obtain pseudo Zernike moment with robust watermark。 S6, for the pseudo Zernike moment with the robust watermarkPerforming pseudo Zernike inverse transformation and rounding operations to obtain an image with a robust watermark。 S7, calculating an image with a robust watermarkPseudo Zernike moments of (A)Then calculate pseudo Zernike momentsAnd pseudo Zernike momentsIs subjected to pseudo Zernike inverse transformation and rounding operation to obtain an error image. Image errorAnd images with robust watermarksPerforming superposition processing to obtain a superposition image。 S8, for the superimposed imageCarrying out a dewatering operation to obtain a dewatering superimposed image。 S9, calculating an original image I and a water stamp superposition imageRounding distortion between。 S10, distorting the quantizationSaid rounding distortionSuperimposed imagesLeast significant bits of the first N pixels of (b) are embedded into an image with a robust watermarkIn the method, an intermediate image containing a robust watermark and a reversible watermark is obtained. Wherein, the Is reversible watermark information. S11, generating an intermediate imageHash value of (a)And the hash value is used forReplacing intermediate imagesLeast significant bits of the first N pixels of (b) to obtain a robust reversible watermark image。 In a second aspect, the present invention also proposes a robust reversible watermark ext