Pulsed illumination signal modulation control & adjustment method and system

One aspect of the invention is a method for signal modulation adjustment. The method comprises illuminating a reference target and a region of film with a first light source for a first time interval. The method further comprises capturing image data from the film in response to a first amount of light reflected from the film with a first sensor for a first integration time. The method also comprises approximately simultaneously producing a first reference output in response to a first amount of light reflected from the reference target in a field of view of a reference sensor. More particularly, the method further comprises adjusting the data in response to the reference output. In a further embodiment, the method comprises adjusting an output illumination level of the first light source in response to the first reference output before a next time interval.