The disclosure relates generally to processing audio and video signals. One claim recites an apparatus comprising: electronic memory for storing a media signal, the media signal comprising degradation introduced through use of a key, in which the key corresponds to detection criteria in the media signal, and in which the degradation comprises human perceptible degradation, the media signal further comprising the key embedded therein; and a processor programmed for: analyzing the media signal to obtain the key; and removing some of the degradation through use of the key, in which said removing utilizes different detection criteria relative to a process that introduced the degradation into the media signal. Of course, other claims and combinations are provided too.