Robust Watermarking in Transform Domain Using Edge Detection Technique

Digital Watermarking is used to embed copyright marks into the digital contents to check copyright violation. In this paper a novel robust watermarking technique is presented. The watermark is embedded robustly either in Discrete Hartley transform (DHT) domain or in discrete cosine transform (DCT) domain depending upon the number of edges in the blocks of the original image. The watermark is embedded invisibly block by block into the blocks of the original image. For this, the threshold number of edges in the original image acts as a key. To extract the watermark, the steps performed in the embedding process are executed in reverse sequence. This technique is demonstrated to be robust against various attacks like salt & pepper, JPEG compression etc. even with severe degradation to the watermarked image.