DCT-Domain Blind Detection Watermarking Algorithm

The digitization of information medium not only provides great convenience for the access of information, but also evidently improves the efficiency and accuracy of information expression. Especially with the development of modern net-communication technique, the exchange and transmission of data becomes very easy. The paper proposes a new image watermarking algorithm —— DCT-domain binary image watermarking algorithm. The algorithm is a blind detection algorithm without the needs of host primary image in the process of extracting watermark. The added watermarking information has good invisibility. And it has better anti-attack capability on JPEG attack of watermarking attack method.

Image Copy Detection Based on DCT Ordinal and Block Median

As for highly repetitive image of Internet, a new image algorithm combined with DCT and block median method is designed. As there is a certain correlation between low-frequency coefficient of DCT and image scaling, the sequence vector of DCT coefficients is introduced with block median method to make up the defect of DCT processing for multi-channel image supplied. Through the combination of DCT and block median method, the recall and precision of new algorithm is over 95%. New algorithm works well in image scaling, resists well against watermarking attack and is able to detect the copy of target image fast and accurately from a large scale image datasets.