Abstract
We propose a low-complexity pixel-based watermarking using edge area in an image. In this method, an image is divided into blocks and the blocks are classified into edge blocks and others. The histogram of pixels in edge block generally shows a bi-modal distribution which has two peaks. Pixels in an edge block are further classified into two classes named “high peak class” and “low peak class”. Then, a bit of watermark information is embedded by manipulating the between-class variance, i.e., by changing the pixel values in each class of the edge block. We utilize the discriminant analysis method for deciding a threshold and manipulating the between-class variance. The proposed method can improve the quality of watermarked image while keeping the robustness against compression and smoothing. In this paper, we evaluate the image quality of watermarked image using PSNR and SSIM. We also evaluate the watermark robustness against JPEG compression and Gaussian filtering.
