An improved blind watermarking method in frequency domain for image authentication

Digital watermarking has been widely used for copyright protection for multimedia data. This paper proposes a new watermarking method of image for copyright protection based on Hadamard transform. This method can embed or hide an entire image or pattern as a watermark such as a company´s logo or trademark directly into original image for copyright protection. This watermarking method deals with the extraction of the watermark information in the absence of original image, hence the blind scheme is obtained. The experimental results prove that our proposed watermarking method offers better image quality and more robustness under various attacks such as JPEG compression, cropping, sharpening, filtering and so on. Peak Signal to Noise Ratio (PSNR) and Normalized Correlation Coefficient (NCC) are computed to measure image quality and robustness. Finally, a comparative study is made against the previous technique.