A novel image recovery method based on discrete cosine transform and matched blocks

Abstract

In this paper, we propose a method for image recovery based on Discrete Cosine Transform (DCT) and finding the best matched blocks by using a part of the fractal compression algorithm. At the same time, we propose a new check algorithm for checking if image blocks are tampered. First, the original image is divided into small blocks. The best matched block of each small block is searched in a particular way. Then the matching information is embedded as backup into other blocks. For the ones that fail to find the best matched blocks, DCT is applied on them and then quantized to be the backup. In order to prevent the backup of the tampered blocks from damaging, we generate 3 backups for each block and embed them into different quadrants. On the receiving side, the tampering check bits are extracted to localize the tampered areas, and the backup bits are used to restore the contents of the tampered regions. The experimental results have proved a good restorability of this algorithm, and the lower the tampering rate is, the better quality of restored content can be obtained.