A system and method for determining a state of a traffic signal. In one embodiment, a traffic signal state detector includes a lens, a color sensor, and a processor. The color sensor is configured to identify a plurality of colors of light directed to the color sensor by the lens, and a field of view of the color sensor is restricted based on dimensions of a traffic signal. The processor is coupled to the color sensor. The processor is configured to determine a color of light emitted by the traffic signal based on the colors of light identified by the color sensor.