Reversible data hiding for VQ-compressed images based on search-order coding and state-codebook mapping

• We propose an adaptive data hiding scheme offering high embedding capacity.
• Scheme combines search-order coding and state-codebook mapping.
• Combination of SOC and SCM makes the size of the output code-stream reduced.

In the field of digital multimedia, numerous researchers have exploited data hiding for providing secure communications. Because most multimedia is compressed in advance to save storage space and transmission time, this paper presents a reversible data-hiding scheme for vector quantization (VQ)-compressed images. In the proposed scheme, search-order coding (SOC) is first employed to reduce the size of the VQ index table. For image blocks that cannot be processed by SOC, a technique called state-codebook mapping (SCM) is used to map the blocks to the corresponding indices in their state-codebooks, which are generated by a set of neighborhood indices. After SOC and SCM, the size of the output code stream is reduced, and a large amount of space is available for embedding sensitive data. Performance comparisons with similar recent studies are presented for demonstrating the superiority of the proposed scheme. The experimental results indicated that the proposed scheme can achieve a high embedding capacity and a high compression bit rate.