1. An image capture system comprising: an image capture unit configured to capture a first image frame comprising a set of pixels; and a processor coupled to the image capture unit and configured to: determine a normalized distance of a pixel characteristic between the first image frame and a second image frame for each pixel in the first image frame, wherein the normalized distance is a non-physical distance; compare the normalized distance for each pixel in the first image frame against a pixel sensitivity value for that pixel; determine that a particular pixel of the first image frame is a foreground or background pixel based on the normalized distance of the particular pixel relative to the pixel sensitivity value for the particular pixel; and adapt the pixel sensitivity value for each pixel over a range of allowable pixel sensitivity values.