A Robust Scheme for Oblivious Detection of Watermarks / Data Hiding in Still Images

We propose a novel, robust scheme for data hiding/ oblivious detection of watermarks in still images. While the low-frequency image coe cients are robust, they cannot be used e ectively for oblivious detection methods, when correlative processing is employed for detection. However, in the proposed non-linear detection method, the robust low-frequency bands can be used e ectively. Thus the proposed method turns out to be more robust than methods employing linear addition and correlative extraction of the signature. We report the results obtained for 7 test images in terms of probability of error in detection of the watermark/ hidden bits.