Circuitry to control reflective optical sensors is provided that reduces false detections due to ambient light without compromising the performance of the optical sensors to detect dark materials. A reflective optical sensor includes an emitter LED and photo-detector arranged to receive light from the LED that is reflected by an object being detected. A first input of a comparator is coupled to the output of the photo-detector. A second input of the comparator is coupled to the output of the photo-detector through a filtering circuit. The filtering circuit operates to filter the detector's output and adaptively adjust the trigger threshold of the comparator, thereby enabling the photo-detector to be sensitive enough to detect dark mail pieces, i.e., those mail pieces that are minimally reflective, while being immune to repeated false triggers due to excessive ambient light.