Adaptive visible watermarking of images
Digital watermarks are emerging as a tool to provide copyright protection for high quality images and video. Though a lot of work has been done in the area of invisible watermarks, relatively less earlier work exists for visible watermarks. As a consensus on the various issues for invisible watermarks to be legally admissible eludes us, a visible watermark could serve as a deterrence to theft and also to provide instantaneous recognition of the owner or creator of an image. We propose a technique in which the location and strength of the watermark image to be embedded is varied in accordance with the underlying content of the image to be watermarked. We propose a new algorithm that classifies each block of 8/spl times/8 of pixels into one of 8 classes depending on the sensitivity of the block to distortion. We analyze the texture, edge and luminance information in the block for this purpose. The embedding process is automated and the bits are embedded in the DCT transform domain. Since the strength of the watermark in a block depends on the class to which the block belongs, the result is a pleasant and unobtrusively watermarked image irrespective of the type of image.