1. A method comprising: scanning a beam of light over a surface in a scan with a variable velocity; detecting light from the surface at different points in time during the scan; generating reduced-noise representations of groups of the detected light that each correspond to a different position in an image of the surface, wherein the reduced-noise representations are generated for groups having a plurality of different sizes, and wherein generating the reduced-noise representations of the groups comprises filtering the detected light within each group with a variable cutoff frequency filter having a variable cutoff frequency including varying the cutoff frequency for different portions of the image of the surface; and generating the image of the surface by representing the different positions in the image with the reduced-noise representations of the corresponding groups.