Studies On Digital Image Information Hiding Techniques

With the rapid development and great popularity of modern communication technology, especially with the wide application of Internet—the combination of communication technology and computer technology, information share, transmission become more frequent and wide. It has brought us great convenience and a great number of information security problems as well. Such as information theft, copyright protection of multimedia data and image authentication. But traditional security protection way-cryptography can't indeed solve the above problems. People bring forward information hiding technology. Practice proved that information hiding Technology can settle a serial of information security issues, and it has become a hot spot in the field of information security research. This paper focuses almost exclusively on information hiding technology based on digital image. In this paper, an introduction of the related concepts, characteristics and application field of information hiding technology is made. Then analyses the existing typical algorithms, pointing out the advantages and disadvantages of them. Then combine the HVS (human visual system) theory, the paper brings forward region-based information hiding techniques and DCT based robust watermarking technique and fragile watermarking technique. Experimental results show that region based information hiding technique has a high degree of invisibility and large data hiding capacity. DCT based robust watermarking technique is to adjust the DCT coefficient to watermark. It is robust to JPEG compression, Gaussian Filtering, Median Filtering and so on attacks. DCT based fragile watermarking technique utilizes Hash function, it uses the lowest frequency components of DCT block which is sensitive to human eyes as the input of Hash function, chooses part of the output of Hash function as the fragile watermark and hide it into middle-band of DCT. When detected, we encrypt the lowest frequency components of DCT of the image to be tested by the Hash function, then compare the output of Hash function and the watermark hided in the image. Then the conclusion whether the image is modified or not is drawn. In the end of the paper, the author gives out some suggests on the possible research directions in the future.