1. An adaptive filter to suppress repetitive high-frequency information in an image comprising pixels, the image having repetitive high-frequency information, comprising: decision circuitry to identify the repetitive high-frequency information in at least a subset of the pixels of the image to provide a repetitive-sequence signal; a low-pass filter to filter the image to produce low-pass filtered pixels; and a switch to output the pixels of the image as adaptive-filter output, and in response to the repetitive-sequence signal, to output the low-pass filtered pixels as the adaptive-filter output.