Improved performance of amplitude modulation based digital watermarking

In this paper, an amplitude modulation based watermarking method is considered. We propose an improved technique using a low-pass filter in order to eliminate some details of image before applying an image luminance in watermark embedding. This pre-processing step provides imperceptibility and colorfulness for the watermarked image. Moreover, an improvement of watermark retrieval performance is achieved as well. The terms of peak signal to noise ratio (PSNR) and normalized correlation (NC) are used to evaluate quality of image and watermark retrieving performance, respectively. The experimental results show that the embedded watermark can resist attacks such as high-pass filtering, JPEG compression and Gaussian noise adding.