Hierarchical recovery for tampered images based on watermark self-embedding

•A novel self-embedding watermarking scheme for tampering recovery is proposed.•MSB-layer bits are interleaved with distinct extension ratios to form reference bits.•Higher MSB layers have greater probabilities to be recovered than lower MSB layers.•Our scheme has better recovered results due to hierarchical recovery mechanism.

In this paper, we propose a new self-embedding watermarking scheme with hierarchical recovery capability. The binary bits in the adopted MSB layers are scrambled and individually interleaved with different extension ratios according to their importance to image visual quality. The interleaved data, which are regarded as reference bits for tampering recovery, are segmented into a series of groups corresponding to the divided non-overlapping blocks, and then embedded into the LSB layers of blocks together with authentication bits of tampering detection. Because the extension ratios of MSB-layer bits are based on the hierarchical mechanism, the efficiency of reference bits is increased, and higher MSB layers of tampered regions have greater probabilities to be recovered than lower MSB layers, which can improve the visual quality recovered results, especially for larger tampering rates. Experimental results demonstrate the effectiveness and superiority of the proposed scheme compared with some of state-of-the-art schemes.