Reversible Information Hiding For Images In Compressed Domain

With the development of computer network technology and multimedia technology, a lot of digital media information begins to utilize the internet to spread. The method is fast and efficient. But it also triggers a serious problem, namely the intellectual property protection of digital media products. Because these digital media files on the internet can easily be copied illegally or tampered maliciously. It will violate the copyright owner’s intellectual property. As a new technology in the field of information security, information hiding technology can solve this problem effectively. Digital watermarking technology in information hiding can embed some watermarks which identify the copyright owner into the digital media products to be published. The embedding of watermarks does not affect the normal use of the products. Once meets copyright infringement, the owner can extract the watermarks from the products to protect intellectual property. Moreover, information hiding technology can also be used in the field of covert communication. Steganography in information hiding can embed confidential information into open cover files such as images and videos. It is difficult for the attackers to find the existence of the hidden information. So it can greatly enhance the security of information transmission.The paper mainly studies reversible information hiding for digital images in compressed domain. It selects two kinds of compressed images to study, namely JPEG2000 compressed image and fractal compressed image. The paper introduces the related knowledge of information hiding in detail first. Then it does the following research works for the research objects:(1) For JPEG2000 compressed images, the paper proposes a reversible information hiding scheme based on block histogram adaptive shifting by analyzing the encoding and decoding processes of JPEG2000 compressed images. The scheme selects quantized wavelet coefficients in high frequency sub-bands as the information embedding position. Then the information can be embedded by blocking and shifting the wavelet coefficient histogram. The experimental results show that the proposed scheme is effective. Moreover, the proposed scheme achieves better performances of embedding capacity and imperceptibility than some existing schemes.(2) For fractal compressed images, the paper proposes a reversible information hiding scheme based on modifying the fractal codes of image. The scheme can affect the values of the first two parameters in the fractal code of each range block by setting the sliding step of domain block to even. Then the information can be embedded by modifying the values of the two parameters. The experimental results show that the proposed scheme is effective.