A Flexible Scheme of Self Recovery for Digital Image Protection

This paper proposes a self-embedding method with flexible restoration capability. We present a method of encoding DCT coefficients of each block into reference bits for self-embedding. In order to improve the restoration capability, we classify the selected coefficients into three types, and assign different bits for each type to generate reference bits. The generated reference bits are embedded into the original image, along with authentication bits derived from the content by hash function. On the receiver side, after identifying tampered blocks by authentication bits, reference bits are extracted from the reserved blocks to approximately reconstruct the principal content of the lost information. Three cases of flexible quality restoration are analyzed corresponding to different tampering rates. Even up to 75% of the protected image is tempered; the original content can still be recovered approximately.