A Reversible Color Image Watermarking Technique using Zero Difference Pairs

Nowadays, reversible data hiding (RDH) schemes play a significant role in multimedia security applications. In general, any digital image consists of smooth and textured regions. In smooth regions, pixel values with high redundancy are shown up in hundreds and tens position. These values for pixels are observed in all three channels Red (R), Green (G) and Blue (B) of color images. Based on this concept, we proposed a novel RDH scheme where each pixel value is split according to their place values and directed into two categories, Higher Order Pixel Group (HOPG) and Lower Order Pixel Group (LOPG). The pixel range of HOPG is 0–25 and that of LOPG is 0-9. Pair wise data from HOPG that has the same pixel values are chosen, and data is embedded at Zero Difference Pairs (RDH-ZPD). Further, to overcome the overlapping issue, pairs with greater than zero difference are shifted by one, and overflow locations are saved along with secret data in HOPG. To improve the visual quality, the respective pixels in LOPG are modified by adding and subtracting constants. The proposed method experimented on standard color images and it is performed well in terms of PSNR, MSE, SSIM, and payload when compared to recent state of art methods. The average values of PSNR, MSE and SSIM when embedded in blue channel are 51.2 dB, 0.5 and 1.00 respectively.