A classification scheme assigns samples of the watermarked media to classes based on classification criteria indicating a likely presence of a watermarked signal. Once classified, the scheme determines statistical characteristics of the media signal for the classes, and assigns a figure of merit to the samples in each class. A watermark decoder (e.g., reader and/or detector) use the figure of merit to adapt a watermark decoding function to the statistical features of the classes, such as weighting to samples to improve watermark decoding.