A REVERSIBLE WATERMARKING SCHEME WITH HIGH PAYLOAD AND GOOD VISUAL QUALITY FOR WATERMARKED IMAGES

High embedding capacity, good visual quality and reversibility are desired factors of information hiding systems. Recently, Thodi and Rodriguez proposed a reversible watermarking method with high embedding capacity. However, embedding capacity and image quality of this method can be improved. Thus, we propose a reversible watermarking scheme inspired by the prediction error expansion (PEE) embedding technique proposed by Thodi and Rodriguez. The proposed method embeds three secret bits into one grayscale cover pixel at a time by using a pixel partition strategy. Experimental results show that the proposed method achieves high embedding capacity measured by bit per pixel (bpp) and good visual quality measured by peak signal-to-noise ratio (PSNR). Specifically, the embedding capacity of the proposed method is about 1.4 times higher than that of the PEE method for all test images. The PSNR value of the proposed method in the range of embedding capacity [0.1, 1) is at least 13 dB higher than that of the PEE method for all test images. The PSNR value of the proposed method at its maximum embedding capacity (around 1.4 bpp) is always greater than 39 dB for all test images. In addition, the proposed method surpasses many existing reversible watermarking methods.