Watermarking schemes that have been developed for continuous tone images cannot be directly applied to halftone images. Many of these watermarking methods require characteristics implicit in continuous tone images but absent from halftones. With this in mind, it seems reasonable to have a robust watermarking technique specific to halftones, equipped to work in the binary image domain. The paper reviews existing techniques and suggests improvements to increase their performance and overcome their limitations. The first set of post-halftone watermarking methods work on existing halftones. Data hiding cell parity (DHCP) works in the parity domain instead of on individual pixels. Data hiding mask toggling (DHMT) works by encoding two bits in the 2/spl times/2 neighborhood of a pseudorandom location. Dispersed pseudorandom generator (DPRG), on the other hand, is a preprocessing method that takes place before halftoning. DPRG achieves better visual results. Using the modified peak signal-to-noise ratio (MPSNR) metric, the proposed techniques outperform existing methods by up to 5-15%, depending on the image type and method considered.

Publication Date



"Improved techniques for watermarking halftone images," Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing 2004 (ICASSP '04). The Institute of Electrical and Electronics Engineers (IEEE). Held 17-21 May 2004. ©2004 Institute of Electrical and Electronics Engineers (IEEE). Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE. This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder.ISBN:0-7803-8484-9 ISSN:1520-6149 Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


RIT – Main Campus