A new casccaded secret image sharing scheme

Secret image sharing based on Shamir´s secret sharing scheme provides fault tolerance and trust to group policy during transmission of secret images over networks. After its initial use, research is focused on improving both visual quality of stego images accommodating shared values and authentication mechanism ensuring correctness of stego images. Most of the methods use LSB embedding to hide shared values and authentication bits into cover images. Reversible steganography is used with LSB embedding and Shamir´s scheme to make shares meaningful in this paper. LSB embedding is used to generate an intermediate stego image hiding most significant four bits of the elements of shared values vector. Least significant four bits of the elements and authentication value generated for shared values vector are embedded into the histogram of the intermediate stego image using reversible Steganography. Proposed scheme ensures improved PSNR compared to other works reported in the literature by using both LSB embedding and reversible Steganography together. Experimental results indicate that stego images have approximately 48 dB PSNR.