Research On Digital Watermarking Algorithm Based On DCT And Optimal Embedding Intensity Factor

With the network and multimedia technology of highly development in the field of information security,the application of digital watermarking technology play an important position in the information hiding technology.As a kind of information hiding technology,Digital Watermarking is a technology which can embed secret information included the product related information or copyright user serial number in digital products,such as digital images,video and audio information etc.The digital watermarking is intended to facilitate tracking piracy,prove the product's true reliability,protect the copyright of digital products or provide additional information about the product.According to relevant documents and information,the thesis provides an overview of watermarking applications and historical background,as well as current research situation in domestic and abroad.Focused on introducing the principle of digital watermarking,classification and characteristics,we describe the evaluation of digital watermarking method,and make detailed analysis of several typical algorithm of digital watermarking.Through treating the image as the object of study,we also explore the digital watermark algorithm based on discrete cosine transform.In this thesis,an improved algorithm is proposed based on the discrete cosine transform algorithm of additive embedding rules.The watermark image is transformed into gray scale and normalized.Two groups of watermarking sequences are randomly generated and then the image is divided into blocks by DCT transform,and then an favourable intensity factor is embedded in the transformed frequency domain coefficients after comparison.In order to protect copyright,the watermark image is encrypted.Through experiments and comparison with the original algorithm,this algorithm can effectively resist white noise,filter and JPEG compression and cutting attacks in the results of tests.