A hybrid encoding method for reducing code stream in EICA-optimized SMVQ reversible data hiding

Abstract

An enhanced imperialist competitive algorithm (EICA)-optimized side-match vector quantization (SMVQ)-based reversible data hiding (VQ-SMVQ with EICA) was developed for embedding higher number of secret bits. This technique improved the embedding capacity rate of compression and quality of reconstruction. However, for improving security and minimizing the length of the output code stream left-upper coding (LUC) was along with SMVQ, since LUC algorithm is more appropriate for compression of SMVQ index table. In this paper, the code stream size is reduced by proposing an efficient encoding approach. Initially an improved locally adaptive coding (ILA) scheme is used for effective distribution of the position of SMVQ indices based on adaptive threshold value. A locally adaptive data compression scheme (LAS) is utilized with IAS to improve the compression rate of secret data simultaneously with embedding capacity. The combined technique is achieved highly reduced length of output code stream. Thus, EICA-optimized SMVQ reversible data hiding with hybridized ILA and LAS outperforms than existing schemes.