Research On Digital Watermarking Algorithm For Remote Sensing Image

Remote sensing data is one of the supportive achievements in the field of national infrastructure and earth science research, and plays a significant role in national economy and defenses. With the accelerating process of the production and application, an important issue that arises in the security and copyright issues of remote sensing data is becoming increasingly salient. It has been recognized for quite some time that current security laws and technologies are inadequate for dealing with the behavior of infringement, disclosure, illegal dissemination and usage.Digital watermarking technology is a new information security technology, and can provide a feasible and practical solution for the copyright protection for the remote sensing image. Digital watermarking is the process of embedding information into digital data such that the information can later be extracted or detected for a variety of purposes including copyright prevention, ownership authentication, infringement tracking and tamper detection. Digital watermarking is being deemed essential to provide a strong technical support to legitimate use of remote sensing data.The digital watermarking models and algorithms for remote sensing image are studied. The main results are as follows:(1) Based on the own characteristics of the remote sensing image, the characteristics and requirements of the digital watermarking technology for remote sensing image are outlined, the types of geometric attacking of remote sensing image are analyzed, and the effects of different geometric attacking on the impact of digital watermarking for remote sensing image are explored.(2) Based on the analysis of the characteristics of remote sensing image, an algorithm based on key matrix and template matching to resisting geometrical distortions is proposed. In the premise of not changing the image in the most significant bit, key matrix is used to embed the watermark, so that to meet the availability of watermarked remote sensing image. In the watermark extraction process, the template matching method is used to improve the watermark extraction correctness.(3) Based on the analysis of geometrical distortion of remote sensing image, an algorithm based on mapping mechanism is presented. To locate the embedded mark, the one watermark information is embedded in more than one pixel value using the function established by image data and watermark. For the different bands of the remote sensing images, different mapping parameters are chosen. The problem of synchronization can be resolved by using the mapping mechanism to determine the location of embedded watermark. The robustness of the presented algorithm is also improved.(4) The advantages of the digital watermark based on DCT for remote sensing image are analyzed. An algorithm based on pseudo-random sequence and block DCT is proposed. The embedded block location is selected by the mechanism of pseudo-random sequence, so as to increasing the security, and improving the efficiency of the proposed algorithm. Based on proposed algorithms, two improved algorithms are presented. These algorithms effectively resist the combined attack of remote sensing images.(5) Taking into account the splice and color adjustment involving the digital mosaic process, the algorithms to resist the splice and color adjustment are studied. There are three algorithms, including the detecting algorithm based on search mechanism of golden section method, the detecting algorithm based on the feature of linearity, the detecting algorithm based on the mechanism of dynamic quantitative. These proposed algorithms can effectively resist the splice or color adjustment.