An extended difference expansion algorithm for reversible watermarking

In this paper, a very high-capacity reversible watermarking algorithm is proposed. The algorithm extends Tian’s method by histogram shifting to form a new type of pixel pair, which is called the shiftable pixel pair. The shiftable pixel pairs can increase the embedding capacity of a digital image while keeping the distortion low. Experimental results also show that the algorithm provides a large embedding capacity without making noticeable distortion. Besides, the original image can be completely restored after extraction.