Design And Implementation Of 2d Digital Watermark System

With the popularizations of internet and the widespread use of digital multimedia technology, the security of information becomes more and more important. Digital watermark has become a popular topic in the field of digital copyright protection. This paper first expounded the background, classification, properties and algorithm of digital watermark. Then it given a brief introduce to singular value decomposition, discrete cosine transform and discrete wavelet transform. The paper deals with the method of how to embed 2d true color images as watermark information into 2d true color images. Based on them, the paper developed mainly in the follow aspects: Present a hybrid watermarking algorithm on DCT and SVD. This algorithm profits from the JPEG compression processing flow, carries on the DCT to the cover image and the watermark image. Then it applies the SVD to each small block of segmented cover image, uses the quantification method to insert the watermark information into each block's largest singular value. The algorithm actualized blind withdraw of watermark information; Present a hybrid watermarking algorithm on DWT and SVD. The algorithm chose lifting scheme and Daubechies9/7 function to finish wavelet transform over cover image and watermark image. Then it applies the SVD to each small block of segmented cover image and inserts the watermark information into cover image the same way as DCT-SVD; Designed and implemented a 2d digital watermark system. The system actualized the embedding and blind withdraw of watermark information over 2d true color images. The system provides basic operation over digital images such as geometric transformation, chrominance adjustment and specially effect in order to evaluate the watermark algorithm; Listed some criterions of evaluating the robust of the watermark algorithm, assessed the above two algorithms. This article proposed two algorithms, its characteristic is that both the primitive carrier and the watermark are true color image; the algorithms can satisfy the transparency and the robustness request of the digital watermark system. The experiment based on the algorithms demonstrates that the watermark is robust to the processing such as JPEG compressing, noise, crop and contrast enhance.