Randomised visual secret sharing scheme for grey‐scale and colour images

Abstract

Randomised visual secret sharing is an encryption technique that utilises block‐based progressive visual secret sharing and discrete cosine transform (DCT) based reversible data embedding technique to recover a secret image. The recovery method is based on progressive visual secret sharing, which recovers the secret image block by block. The existing block based schemes achieve the highest contrast level of 50% for noise‐like and meaningful shares. The proposed scheme achieves a contrast level of 70–90% for noise‐like and 70–80% for meaningful shares. The enhancement of contrast is achieved by embedding additional information in the shares using DCT‐based reversible data embedding technique. Experimental results showed that the proposed scheme restores the secret image with better visual quality in terms of human visual system based parameters.