Halftone image watermarking based on visual cryptography

The advancement of digital image emphasizes the need for copyright protection. Digital watermarking is one of the most popular techniques and a very active research area for copyright protection of documents and media. In this paper, we propose a watermark technique for halftone image based on visual cryptography technique. The proposed method is simple and efficient. We introduce error diffusion techniques for halftoning; three most known filters of error were used: Floyd and Steinberg, Jarvis and Judice and Ninke and Stucki methods. The system security is guaranteed by using a visual cryptography approach to generate two random shares of a watermark; public watermark and secret watermark.