Digital Watermarking using Spread Spectrum Techniques

Abstract

A digital watermarking scheme, based on the spread spectrum techniques, is proposed in this paper. The scheme uses the frequency hopping spread spectrum technique to determine positions for watermark embedding in the original image, while the direct sequence spread spectrum technique is used to provide robustness to the watermark signal. This scheme has an advantage over the existing spread spectrum watermarking schemes, that is, various levels of watermark signal can be embedded into the original image in order to minimize the quality degradation of the watermarked image. To embed the watermark signal, the selected bits of selected pixels are used to carry the watermark signal. The performance of the watermarking scheme is evaluated by using the Peak Signal to Noise Ratio (PSNR). The experimental results indicated that the proposed scheme gained higher PSNR and, simultaneously, more watermark bits could be embedded into the original image.