Wavelet Transform Based Digital Watermarking And High Dynamic Range Image Compression

Wavelet analysis is one of the hot spots in applied mathematics, compared with Fourier analysis, wavelet analysis is a local analysis technique on both spatial and frequency domain, and thus it can be used for information extraction. Through scaling and shifting, wavelet analysis can be used to analyze signal on multi-scale, which can not be achieved with Fourier anyalysis. Wavelet analysis has been applied to signal processing, speech synthesis, pattern recognition, computer vision, data compression, earthquake exploration etc. In this paper, tow topics are studied. The first one is wavelet based image watermarking; the second one is wavelet based high dynamic range image compression.With the rapid increase of Internet users and the fast development of the multimedia technology, digital multimedia has been more and more popular. It becomes urgent to find a way to protect the copyrights of digital product owners and prevent the piracy of digital products because it is much easier to transmit, copy, tamper and pirate digital products. As digital watermarking technology is an effective tool of copyright protection, it has gained more and more concerns since it appeared in 1993. So far, watermarking technique is not mature, since general watermarking technique is only robust to some kinds of attacks, but not robust other kinds of attacks. Taking the advantage of the multi-scale analysis property of wavelet analysis, we put forward a multiple watermarking technique, in which, watermarks are embedding into defferent wavelet coefficients to make them are complementary to each other to boost the robustness. Besides, the watermarking technique is a blind watermarking technique, which means the extraction of watermarking can be done without exposing the original host image, and thus provides higher security. From the experimental results it can be observed that proposed method is robust to a wide variety of attacks. Comparison with the existing methods shows the superiority of the proposed method.High dynamic range imaging (HDRI) is a set of brand new digital imaging techniques, which aims to accurately represent the color and illumination information of the original scenary. Because of the huge information storage requirement, people definitely need an efficient high dynamic range image compression algorithm.The standardization of JPEG2000 show us the power of wavelet based image compression, in which a still color image can be compressed to 1/100 of its original size with acceptable visual quality. In this paper, we put forward a wavelet based high dynamic range image compression algorithm which is capable of compressing a high dynamic range image to 1/10 of its original size with acceptable visual quality.