Improved Exploiting Modification Direction Method by Modulus Operation

The EMD method proposed by Zhang and Wang fully exploited modification directions. Modifications in different directions were used to represent different secret data. According to the experimental results, the highest capacity was demonstrated in the 5-ary notational system, where only one secret digit is embedded for each two pixels. But this is an inefficient method because it can be hidden more secret data without revealing to the human visual system. To improve an embedding capacity, Chang et al. proposed two-stage EMD method, Lee et al. restricted to 8-ary embedding for the EMD method, and also Lee et al. segmented the pair of cover data into two parts to embed higher secret data. But still have a room for hiding more secret data. This paper proposes an improved method of the EMD method to hide more secret data while maintaining a high PSNR value. The proposed method can embed secret bit on every pixel of cover data. The experimental results demonstrate that the proposed method has a high capacity and good visual quality.