Chirp-Based Image Watermarking as Error-Control Coding

In this paper, we use post processing methods to compensate the bit errors occurred in watermark embedding and extracting. Forward error correction (FEC)-based and chirp-based techniques are applied to encode and shape the embedded watermark message so that even at the presence of some bit error rates (BERs) in the extracted watermark, the watermarking algorithm be able to successfully estimate the correct embedded watermark message. Repetition and Bose-Chaudhuri-Hocquenghem (BCH) codings are used as two well-known FEC schemes, and discrete polynomial transform (DPPT) and Hough-Radon transform (HRT) are utilized as two chirp detectors in chirp-based watermarking. Robustness of all the proposed post processing methods are tested for checkmark benchmark attacks, and we found that the chirp-based watermarking using the DPPT chirp detector offers the highest watermark extraction rate, and the best bit error compensation even at BERs of higher than 17%.