The technology described in this document can be embodied in a method that includes receiving during a first time period, information from a first sensor representing a target illuminated by a first illumination source radiating in a first wavelength range, and information from a second sensor representing the target illuminated by a second illumination source radiating in a second wavelength range. The method also includes receiving during a second time period, information from the first sensor representing the target illuminated by the second illumination source radiating in the first wavelength range, and information from the second sensor representing reflected light received from the target illuminated by the first illumination source radiating in the second wavelength range. The method also includes generating a representation of the image in which effects due to the first and second illumination sources are enhanced over effects due to ambient light sources.