Pixel Grouping of Digital Images for Reversible Data Hiding

Pixel Grouping (PG) of digital images has been a critical consideration in the recent development of the Reversible Data Hiding (RDH) schemes. While a PG kernel can define pixel-groups with the different neighborhoods for better embedding rate-distortion performance, only the group of horizontal neighborhood pixels of size 1× 3 has so far been considered. In this paper, we, therefore, construct the PG kernels of sizes 3×1, 2×3 and 3×2, and investigate their potentials to improve both the embedding capacity and the embedded image quality for a PG-based RDH scheme. A kernel of size 3×2 (or 2×3) that creates a pair of pixel-triplets (i.e., two L-shaped blocks) and offers a higher possible correlation among the pixels. These kernels thus can be better utilized for improving a PG-based RDH scheme. Considering this, we develop and present an improved PG-based RDH scheme and the computational model of its key processes. Experimental results demonstrated that our proposed RDH scheme offers reasonably better embedding rate-distortion performance than the original scheme.