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 coefficients are robust, they cannot be used effectively 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 effectively. 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.