JPEG recompressed image tampering positioning method

Abstract

The invention relates to the field of digital image forensics technology, and more particularly to a JPEG recompressed image tampering positioning method. The method includes the steps of S1, estimating a DCT coefficient value, and calculating values of a DCT coefficient C1 of a tampered region and a DCT coefficient C2 of a non-tampered region; S2, building a hybrid model of the DCT coefficient distribution by a normalized gray gradient co-occurrence matrix; S3, calculating the DCT coefficient conditional probability with unknown parameters; S4, estimating the unknown parameters, and substituting the estimated parameters into the step S3 to obtain the DCT coefficient conditional probability without the unknown parameters; S5, calculating a tampering probability map at a certain frequency f; S6, obtaining a tampering probability map of a DCT coefficient block; S7, post-processing the tampering probability map using connectivity and Gaussian weight filtering; and S8, positioning the tampered region. According to the invention, the second-order gray gradient co-occurrence matrix is used for the first time to model the hybrid distribution of DCT, and a more accurate hybrid distributionmodel is obtained, such that the JPEG recompression tampering positioning can be more accurate.

Description

technical field [0001] The present invention relates to the technical field of digital image forensics, and more specifically, relates to a JPEG re-compressed image tampering positioning method. Background technique [0002] With the popularity of networks and smart devices, the importance of digital images in information dissemination has become increasingly prominent. However, due to the rapid development of digital image editing technology, the tampering of digital image content is becoming more and more easy, which brings challenges to the authenticity and security of digital images. Therefore, how to realize reliable authentication of content authenticity and security in the process of dissemination, sharing and application of digital images has important practical significance. [0003] JPEG image recompression tampering detection is an important branch of digital image forensics technology, its purpose is to detect whether there is tampering in digital images, that i...

AI Technical Summary

Problems solved by technology

[0004] The existing JPEG image re-compression tampering positioning technology is mainly divided into two types: one is to compress the image again, and use the statistical difference of the DCT coefficients before and after compression to determine which DCT coefficient values ​​​​may be tampered. This method locates suspicious areas based on these suspicious points, but this type of method has applicable conditions. When the first quantization factor is greater than the second quantization factor, the method fails; the other is based on the conditional probability mixed model for solution.

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