JPEG grid detection based on the number of DCT zeros and its application to automatic and localized forgery detection

This work proposes a novel method for detecting JPEG compression, as well as its grid origin, based on counting the number of zeros in the DCT of 8 × 8 blocks. When applied locally, the same method can be used to detect grid alignment abnormalities. It therefore detects local image forgeries such as copy-move. The algorithm includes a statistical validation step which gives theoretical guarantees on the number of false alarms and provides secure guarantees for tampering detection. The performance of the proposed method is illustrated with both quantitative and visual results from well-known image databases and comparisons with state of the art methods.