Geometric Distortion Resilient Watermarking Based on a Single Robust Feature for Still Images

Many watermarks for still images are robust against common signal processing techniques, mainly JPEG compression, noise adding and low-pass filtering, while they are sensitive to geometrical manipulations, that yield desynchronization errors. In this paper it is proposed a feature extraction method based on the Radon transform, whose aim is to identify an unique (and robust) feature from the image spectrum. The embedding, which exploits the extracted feature, is based on a multiplicative rule which shapes the watermark to improve the perceptual quality of the marked image. The properties of the extracted feature allow to resynchronize the detector and the embedded watermark even if the image undergoes both geometric manipulations and signal processings, so that the correct watermark retrieving is guaranteed. Experimental results confirm the effectiveness of the feature extraction method and demonstrate that the robustness of the watermark is reached retaining a good perceptual quality in the watermarked image.