Image Watermarking Research

With the rapid development of Computer Network and Capacity for storing information, the digital media can be duplicated and transmitted rapidly at almost no cost. But digital media can be easily duplicated and tampered, so the security of digital media cannot be guaranteed. But it's hard to protect the security of digital media by the traditional digital encryption, because the security of digital media would not be protected after decryption. In order to compensate the default of encryption, digital Watermarking comes forth. Digital Watermarking is a new technology for the copyright protection to the digital media in the networked environment. It can protect the security of digital media effectively through the detecting the watermark embedded in the media. The appearance, application, watermark system principle, classifications and attacks are outlined in this paper.This paper focuses on digital watermarking on images. First, The appearance, application, watermark system principle, key techniques are outlined in this paper.The folio wings are our contributions:1. Information theoretic approaches are concerned with capacity in this paper, and optimal convert and attack policies are analyzed. And applying these conclusion to image, the watermark capacity of image is approximately calculated.2. The author analyzes Wavelet Domain watermarking and DWT how to be applied to digital watermark, and compares with DCT Domain watermarking by experiment. Also combining with image coding to analyze digital watermarking.