Reversible Steganography for VQ Indices Using the Modified State Codebook

In this paper, we propose an information hiding scheme to embed secret information into the compression code of an index table. First, the codewords neighboring the current processed index along with their closest codewords form a state codebook. Two indices of the state codebook are reserved as indicators. Once the current processed index satisfies some pre-defined conditions, the current processed index can be encoded using the state codebook, and the secret bit can be embedded in the compression code. On the other hand, the reserved indices are taken as indicators to denote that the current processed index is encoded by the VQ mechanism. On the basis of our experimental results, the bit rates of the proposed method are lower than those of related works. The improvements in bit rates increase when the quantity of the embedded bits increases.