Research On Digital Image Watermarking Technique Based On Transform Domain

This article started from the background of watermark and invited the product, embedding, detected technique and relevant value target of watermark. On the bases of it, according to the robust digital watermarking, deeply research on choosing digital image as watermark's embedded object is done. The mainly investigation and innovative result is as follows:First of all, System summarized correlative basic knowledge and status research of digital watermark's technique.Second, a robust digital watermark algorithm based on difference dither modulation is proposed. This algorithm adopted spreads and modulations the watermark signal and then the middle and low frequency coefficient pairs are selected to embed watermark signal randomly; Finally, the primary factors affecting robustness and imperceptibility are analyzed. The results of experiments show that this scheme can resist not only JPEG compression and cropping attacks effectively, but also the low pass filtering in a certain extent.The third one, made the DCT and DWT fell together, a robust digital watermarking based on zerotree algorithm is proposed. First, code the original image according to the zerotree; second, made all of the DCT coefficient which transformed assemble again, and then made the same way same frequency band coefficient together and code it. The third, transformed the recomposition's DCT coefficient again; at last, find the relative zerotree of DCT coefficient from the transformed coefficient, then embedded in and analyzed its imperceptibility. The experimental results showed that this algorithm can resist the attack of JPEG compression and cropping attacks effectively and it can resist the attack of noise but also the low pass filtering in a certain extent.Finally, conclude this paper and present further research aspects of the digital watermarking technologies.