Digital Watermarking Research And Realization Based On DWT Domain

Due to the development of information technology and internet, digital media has been widely applications. It brings people convenience, but also some illegal person provides malicious tampering and attack. Digital watermarking technology prevents the information on the Internet. The main way through the original data in the digital works is embedded some important information, and still can verify the integrity of the content.Digital Watermarking mainly study in images, audio, video and three-dimensional grid data watermarks, and the paper focuses on the discrete wavelet transform using the algorithm embedded watermark image. Taking into account the watermarked image needs to find a balance between invisibility, robust and watermark capacity, we made the following studies:(1) Dray image as the host image, discrete wavelet transform can use characteristics of human visual space-frequency characteristics to embed watermark. The carrier image makes discrete wavelet secondary decomposition, and the watermarking signal is embedded into the carrier image wavelet secondary decomposition of intermediate frequency, high-frequency wavelet coefficients to realize watermarking embedding process.(2) It presents a color image watermarking algorithm design. The host image and watermark image are selected 32-bit true color images. First, the various color image components apart, and then separately each component is discrete wavelet decomposition, obtaining after decomposition of all the frequency coefficients. Setting embedding strength factor, the watermark signal is embedded to each components frequency coefficients, and then layers of the embedded watermark image reconstruct image. Finally three layers of gray image is superimposed on three color compounding color images, and ultimately we get the full color image after embedding.In this paper, the gray image watermarking algorithm has achieved better invisibility and robustness.The algorithm is still has good robustness which resist the attacks such as compression and geometric distortion of the filter, add noise. Then, this paper expands the range of host images to color images, but the color image watermarking technology in theory is not very mature, still in development stage. It will be the direction of future research.