Research On Digital Watermarking Algorithm For Color Images Based On Second Generation Wavelets

On the basis of the first generation of wavelet transform, this thesis discusses a blind watermarking algorithm of color image based on lifting scheme wavelet.The algorithm embeds watermark twice: First, the watermark images are embedded in the low-frequency part of the original image based on the improved algorithm of singular value, and then, watermark images are embedded in the non-low-frequency part of the original image based on the algorithm of interval mapping.In the extraction of the watermark, the algorithm firstly extracts watermark in the low-frequency part of the original image. If the watermark is not extracted or not effective, then the algorithm will extract watermark in the non-low-frequency part of the original image.The simulation experiments show that the algorithm for watermarking images have dual protection role, which will extract integrated watermark image from the original image of any part of the damage, and achieve very good results.The comparison with other algorithms, we prove that the algorithm not only ensure a good visibility of the watermark, but also achieve a better robust to against attack, such as cut, JPEG compression, filtering, noise and cut low-frequency.