An efficient IPVO based reversible data hiding method using four pixel-pairs

In the Improved Pixel Value Ordering (IPVO) reversible data hiding method first, a block of n pixels is sorted in ascending order. Then two pixel-pairs are established from the first two pixels and the last two pixels of the sorted block to embed at most two data bits. This paper uses the first three pixels and the last three pixels of the sorted block to form four pixel pairs for embedding at most four data bits. In fact, on the right, using the IPVO technique to embed data bits in the pair of (n − 2)−th and (n − 1)−th pixels and the pair of (n − 1)−th and n−th pixels. Embedding data bits in two pairs of pixels on the left is done similarly. The pixel pairs here all consist of two consecutive pixels in a sorted pixel block, so the embedding efficiency is high. Compared with IPVO-method, the proposed method has doubled the number of pixel pairs used, and the embedding capacity increased from 1.5 to 1.9 times depending on the smoothness of the original images. The experiment results are shown that the proposed method has a superior embedding capacity compared to the existing Pixel Value Ordering(PVO)-based reversible data hiding methods while maintaining good stego image quality.