رویا قاسم خانی

Digital watermarking is a technique for protect copyright of digital images. A good watermarking algorithm must satisfy imperceptibility, robustness and high data hiding capacity. In this paper a novel robust watermarking scheme in Hadamard transform domain for digital image is proposed. For embedding watermark bits we modify the DHT coefficient of two adjacent blocks in same position.DHT coefficient of each block is modified to bring the difference from the adjacent block coefficient in a specified range. This scheme is working for colour as well as gray scale images with any size. Watermark can be a string of characters or a binary image. This algorithm offers advantages of simple implementation, low computation cost, good fidelity and high resiliency under compression. The experimental results and performance analysis shows good robustness under JPEG image compression and other common image processing operations like cropping, rotation, noise addition and filtering.