arithmetic coding

This paper presents a reversible data hiding method in encrypted image that employs correlation of neighboring pixels in the image. In the proposed method, original image may be encrypted by desire encryption algorithm. More significant bits of the pixels in the image are exploited to vacate room for embedding data bits. In the approach, image is divided into separated blocks and most central pixel of each block is considered as reference one. The prediction error between the intensity of other pixels and reference one is calculated and denoted local prediction. This error is analyzed determining a feature of block embedding capacity. Calculated features for all blocks are compressed employing arithmetic coding and embedded in the image along with data bits. At the recipient, at first, compressed features are extracted, then they are uncompressed and used to lossless reconstruction of the original image and extraction of the data bits. Experimental results confirm that the proposed algorithm outperforms state of the art ones.