Abstract: A position detection system can utilize multiple optical responses to a detection scene, such as by using multiple different patterns of light for imaging a given detection scene. The multiple patterns can include a first pattern containing image data that can be used to separate reflected light from retroreflected light in a second pattern of light. This can be used to reduce errors, such as false detections due to directly-reflected light, and/or can be used for identification of objects in the touch detection scene when the objects themselves are optically configured to appear differently in different patterns of light.