Splicing Tampering Detection And Recovery Based On DCT Hashing

As a very important information carrier,digital image has become an integral part of life.However,with the development of information technology and the continuous improvement of digital image processing technology,tampered images are flooding the Internet and various media.The tampered image reduces the credibility of the image,not only affects people's daily life,but also causes adverse consequences in the fields of military,media and medicine.Therefore,digital image forensics technology,which can judge the authenticity and integrity of images,is particularly important.At present,image tampering mainly includes copy-move tampering and image splicing tampering.In this thesis,we propose an image tampering detection algorithm based on DCT image hashing technology.At the same time,the tampered image is restored preliminarily.The specific research contents are as follows:In the process of JPEG compression,the DCT coefficient matrix of the Y channel after DCT is first extracted,then the image hashing is constructed by DCT coefficients,and finally the image hashing is embedded in the header of file of the compressed code stream.At the time of tampering detection,a tampering image hashing is constructed by compressed code stream corresponding to the tampering image,and then compared with the embedded original image hashing for initial detection.In order to achieve the pixel-level detection,a method of secondary detection was proposed based on the preliminary detection results.The experimental results show that the proposed algorithm not only has good robustness,but also has a shorter hash length and a 10% higher detection accuracy.Finally,on the principle of image recovery algorithm based on watermark technology,this thesis proposes an image recovery algorithm based on hash and watermark technology by using hash for watermark information.