Improving the performance of lossless reversible steganography via data sharing

In recent years, pixel value ordering (PVO)-based information embedding techniques have been broadly applied in reversible steganography. So far, researchers have focused on finding the best predictor value to decrease the image distortion. In practice, the secret data size is the main factor that affects the quality of the restored cover image. Therefore, in this research we introduce a technique to reduce the data size. The technique is based on data sharing in which the sender and the receiver share the same “vocabulary table” (VT). Using this VT, any secret datum (text, image, or sound) can be converted to a list of indices. Encoding this list using another lossless encoding method, we can compress the datum greatly, and thus reduce the distortion caused in the embedding process. Experimental results show that the proposed method outperforms existing PVO techniques. The proposed method can save around 80% of data space for text data, and about 98% of data space for image data.