Enhanced Performance of Spread Spectrum Based Image Watermarking with Small Chip-rates
Pradit Trammanontikul, Thumrongrat Amornraksa · 2006
In this paper, we present a method of enhancing a spatial domain spread spectrum (SS) based digital watermarking. By limiting the magnitude of watermarked pixels to be within predeflned ranges, the performance in terms of quality (PSNR) and accuracy (NC) can be improved. This approach is helpful and practical in a situation where the watermarking schemes are used with small values of chip-rate e.g. when we need to embed a graphic logo into an image. In the experiments, the performance of the proposed watermarking scheme is evaluated and compared with the existing ones i.e. the traditional and the Hartung’s schemes. Its robustness against some particular types of attack, i.e. Gaussian noise addition, watermark counterfeit, image cropping and rotation, is also evaluated and discussed.