Dynamic improved pixel value ordering reversible data hiding

The existing reversible data hiding (RDH) methods based on improved pixel value ordering (IPVO) use only a small portion of the pixels (e.g., at most six pixels) in a block for embedding data. Our proposed method is a dynamic IPVO RDH, which can flexibly modify the number of pixels in a block by classifying the local complexity into multiple levels. For a highly-correlated, smooth block, almost all of the pixels, except for one or two in the middle positions, can be involved in embedding data. For a lowly-correlated smooth block, only two pixels can be embedded with data, and no data can be embedded into a highly-textured block. Thus, it is apparent that the redundancy among pixels is fully exploited, and further, more data can be embedded into smooth blocks while maintaining lower distortion. However, when all of the levels are used for embedding data, the visual quality may not be maximized for a given payload. Hence, in our method, we traverse from the first level to the highest level to search for the optimal number of levels that can provide the best embedding performance. Extensive experiments have demonstrated that the proposed method outperforms the existing methods.