The CNTR sensor combines small spot size and fast response to achieve high-speed contrast detection capable of detecting a wide variety of marks and objects. The CNTR effectively detects contrast differences between many colors on various surfaces over a range of 50 grayscale levels. The modulated white light source in the CNTR is focused on a 2.5 to 3 mm spot and directed toward a target. The diffused light returning to the sensor is measured. When the level is equal to or exceeds the threshold the discrete output changes state. Due to the fast response of the sensor, it is suitable for use in high-speed applications. The sensor provides a discrete output that automatically configures NPN and PNP. A PLC or a computer can be used to monitor the status of the discrete output signal.