An Image Watermarking Scheme Based on DWT and DFT

Watermarking has been a popular research area inrecent years due to its wide application. In this paper, a briefwatermarking algorithm based on Discrete Wavelet Transform(DWT) and Discrete Fourier Transform (DFT) is proposed. Inthe embedding process, we apply DFT to one of the sub-bandresulting from DWT. We embed the watermark image bydirectly modifying the coefficients of magnitude spectrum orphase spectrum according to the pixel value of them. Andwatermark extraction is the reverse process of embedding. Weonly need the watermarked image and the original image. Wecompare the magnitude watermarking method and phasewatermarking method according to its invisibility, peak signalto noise rate (PSNR), error rate and robustness to differentattacks. The results show that our algorithm is robust undervarious attacks such as adding noises, rotation, cropping,JPEG compression and filtering.