A new scheme of robust image watermarking: the double watermarking algorithm

Abstract

This paper is an attempt to describe the concept of double watermarking. The latter term refers to a new watermarking algorithm based on embedding mark (signature) in both spatial and multi-resolution domain. For the purpose of increasing the image watermarking robustness against attacks of an image transmission, we encode with a turbo code an image-embedded mark. This new scheme of image watermarking is able to embed 2000 bits in medical images. Results of experiments carried out on a database of 30- 256x256 pixel-sized medical images show that watermarks are robust to Noises, Filter attacks, JPEG Compression and geometric distortion such as Cropping. Results demonstrate that fidelity can be improved by incorporating a codage that is shaped into the embedding process. Other advantages of the two embedding domains are to preserve intellectual features and to secure the mark in the image. The image degradation is measured by Relative Peak Signal to Noise Ratio (RPSNR). Experimental results show that this unit of measurement is the best distortion metric witch is correlated with Human Visual System (HVS); and therefore more suitable for digital watermarking.