The present disclosure relates generally to cell phones and cameras, and to digital watermarking involving such cell phones and cameras. One claim recites a method comprising: measuring distortion introduced by a cell phone camera; using a programmed electronic processor, quantifying the distortion; and providing quantified distortion as feedback to adjust a digital watermark embedding process in view of the distortion introduced by the cell phone camera. The act of quantifying distortion may include, e.g., quantifying a spatial frequency response (SFR) of the cell phone camera. Of course, other claims and combinations are provided too.