Variable block size based adaptive watermarking in spatial domain

In this paper, watermarking for still images is proposed. Image watermarking is performed in the spatial domain which is not only easy but also provides a good result. A watermark image as binary image is embedded onto an original image by using a method whereby gray levels of pixels in the original image blocks are modified to an appropriate intensity of block. Variation of watermark image bits in order to embed the original image block selected affects the embedded block intensity and also it depends on the original image block intensity. The block size is adapted as the intensity of the original image and the capacity of the watermark image in order to embed. With the method of varying block size proposed, the effect of block size adaptation is good and also the watermark image is robust to a number of types of degradation. With the proposed method, the quality of the original image is least affected.