Improvements of EMD Embedding for Large Payloads

A novel steganographic method by exploiting modification direction in digital images was proposed by Zhang et al, in which each secret digit in a (2n+1)- ary notational system is carried by n cover pixels, and only one cover pixel increases or decreases by 1 at most. In other words, the (2n+1) possible values of a secret digit correspond to (2n+1) possible ways of modification to the cover pixels. It can provide higher embedding efficiency and embedding rate than those of matrix embedding. In this paper, we propose an improved EMD embedding method to increase the embedding rate (number of secret bits embedded in each cover pixel). And from the experiments, we show that our improved method still can preserve good stego image quality.