1. A method comprising: capturing, by a computing device, a first image using a first exposure length; determining that x pixels in the captured first image are properly-exposed and that y pixels in the captured first image are improperly-exposed; based on the y improperly-exposed pixels, determining a second exposure length; capturing a second image using the second exposure length, wherein the second image includes y′ pixels that correspond to the y improperly-exposed pixels in the first image; and combining at least some of the x properly-exposed pixels from the first image with at least some of the y′ pixels from the second image to form a composite image.