Signed digit data hiding scheme

The EMD (Exploiting Modification Direction) method by Zhang and Wang uses ( $2n+1$ )‐ary notation to achieve secret message embedding into a cover image. However, the maximum capacity of this method is $1.16\text{bpp}$ for cover pixel number $n=2$ . Its embedding capacity rapidly decreases when selected pixels increase. In order to improve this shortcoming, a new data hiding scheme based on MSD (Modified Signed‐Digit) is proposed. There are three major contributions in this proposed scheme. The first is only $\lceil \frac{n}{2}\rceil$ pixels will be modified and the value is +1 or ‐1 when the group has n pixels. Secondly, the embedded capacity maintains at least $1\text{bpp}$ when n is increasing. The last is the stego image quality is better than $52\text{dB}$ when the cover image's pixels are greater than 4 for each group.