JPEG Compatible Secret Sharing Scheme with Enhanced Performance

Secret leakage and DC overflow are two critical challenges in secret image sharing (SIS) for JPEG images, with the latter also leading to format incompatibility. To tackle these two issues, a systematic investigation on SIS for JPEG images is presented. The primary contribution of this paper is the design of two fundamental components, DC secret sharing and AC secret sharing, for encoding the DC and AC coefficients, respectively, of a JPEG secret image. In DC secret sharing, DCA sharing and post-processing are combined together to deal with DC components. Notably, a partial shadow-adjustable secret sharing (PSASS) mechanism and a sample-recalculate strategy are devised to prevent DC overflow. In AC secret sharing, the AC cross-segment permutation and global scrambling are adopted to disorder AC coefficients, enabling the dramatic alternation of AC block features. The ACA sharing is then employed to encode the permuted AC coefficients. Extensive experiments and comparisons confirm the effectiveness and superiority of the proposed scheme. Compared to recent methods, our approach successfully eliminates secret leakage and avoids DC overflow, thereby ensuring full compatibility with the JPEG format.