Reversible Information Hiding And Lossless Image Authentication Technology

Data hiding is an important technology of information safety in the internet era, and becomes a hot point in the world wild. In some special fields, like medicine and laws, modification of image is not permitted; tiny change of a pixel may leads to wrong result of diagnose or failure of a suit. As a new method of satisfying the special applications, reversible data hiding becomes an important branch of information hiding. Lossless image authentication not only authenticate the authenticity and integrity of the image, but also restore the carrier image exactly, it attracted more and more attentions.Reversible data hiding algorithm based on difference matrix of the original image is proposed in this paper, the property of central distributing of the elements in the difference matrix is used to generate the embedding space, the secret information is embedded through modifying the elements of the difference matrix, and this can be mapped to the modification of the pixels of the carrier. The secret information can be extracted by receiver, and the carrier can be restored exactly. The visual quality of the image is guaranteed, and it has large capacity, simple algorithm and perfect performance. An expansion algorithm is produced to increase the embedding capacity.An image authentication algorithm based on fragile watermarking is proposed in the basis of lossless data hiding. Summary of the image is generated through Hash function and the difference matrix of the carrier, then the summary is embedded in the carrier as a watermark, tamper of the image can be measured, and a 2×2 tamper can be located. The advantage of this algorithm is that the authenticity of the non-tampered area is guaranteed. Experiment shows that the tamper can be measured exactly and can be located.