Hiding clinical information in medical images: an enhanced encrypted reversible data hiding algorithm grounded on hierarchical absolute moment block truncation coding

Reversible data hiding in the encrypted domain has attracted a lot of consideration because of the necessity for content security and protection assurance. Majority of the prior reversible data hiding algorithms are designed for absolute moment block truncation coding (AMBTC) compressed images. In this paper, an enhanced encrypted reversible data hiding algorithm grounded on hierarchical AMBTC has been proposed. In the proposed algorithm, high mean table, low mean table and bitmap sequence table obtained through hierarchical AMBTC are first encrypted using homomorphic cryptosystem and then a secret ternary data is embedded in each grey pixel of high mean table, low mean table and bitmap sequence table (except zero (0) value) without any underflow or overflow issue. Exhaustive experiments have been performed on natural and medical test images which demonstrates the superiority of the proposed algorithm over the existing reversible data hiding algorithms. Experimental study reveals that the proposed algorithm has more payload with superior image quality than the existing algorithms.