This study proposes two reversible data hiding (RDH) schemes for vector quantisation (VQ)-compressed images based on switching-tree coding (STC) and dynamic tree-coding scheme (DTCS). Most developed VQ-based RDH schemes produce non-legitimate codes as output. In order to preserve the legitimacy of the embedded VQ code, some schemes embed data into VQ indices by employing an index replacement mechanism and some other schemes perform embedding by adopting one of the possible ways during encoding each index when multiple ways are possible to encode the index. In the current research, two schemes are proposed based on the second mechanism. Outputted code of the proposed schemes is a legitimate STC/DTCS code and the conventional STC/DTCS decoder can decode it to the original VQ index table. The experimental results show that the proposed schemes are feasible and in comparison with some previous RDH schemes, the first one provides higher embedding capacity and the second one embeds a substantial amount of data while provides lower bit rate than most the previous schemes. In addition, the embedding-efficiency of both proposed schemes is higher than that of the previous schemes.
This paper proposes a reversible data hiding scheme for vector quantization (VQ)-compressed images based on search order coding (SOC). Data is embedded by choosing one of the possible ways to represent each embeddable index and outputted code is legitimate SOC code. The proposed scheme has two advantages. First it is more secure, comparing with previous SOC based schemes that generate non-legitimate codes as output. Second it can be used beside other schemes to embed more data and also it is a solution for the problem of transmission of side information of schemes which their outputs are legitimate VQ codes.
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