Efficient reversible data hiding for VQ-compressed images based on index mapping mechanism

•A novel reversible data-hiding scheme for VQ-compressed images is proposed.•We create index mappings by VQ indices with zero and the largest occurrence numbers.•The indices in each mapping correspond to binary representations of secret subsets.•Mapping optimization by index histogram is conducted to obtain high hiding capacity.•Data embedding can be achieved through the simple index substitution operation.

In this paper, we propose a novel reversible data-hiding scheme in the index tables of the vector quantization (VQ) compressed images based on index mapping mechanism. On the sender side, the VQ indices with zero occurrence numbers in a given index table of an image are utilized to construct a series of index mappings together with some indices with the largest occurrence numbers. The indices in each constructed mapping correspond to the full binary representations with the length of the mapping bit number. Through the mapping optimization by index histogram, the optimal vector of mapping bit numbers can be obtained, which leads to the highest hiding capacity. Data embedding procedure can be easily achieved by the simple index substitutions according the current subset of secret bits for hiding. The same index mappings reconstructed on the receiver side ensure the correctness of secret data extraction and the lossless recovery of index table. Experimental results demonstrate the effectiveness of the proposed scheme.