Electronic watermarking is an active area of research with many applications being foreseen. Watermarks may be-come an essential tool for copy management in future Consumer Electronic or PC devices. With simple circuits, detection of watermarks &amp;er noise addition, MPEG com-pression, D/A conversion, pixel shifts appears feasible, but detection after transformations, such as cropping and stretching, remains a challenge. We propose a model to evaluate the effect of scaling on the detector reliability and venfy it with experiments. 1