There is herein described a light output control method for a controlling a lighting device by a motion of an object near an environment, the lighting device comprising a video sensor and a light-emitting unit, the light output control method comprising steps of emitting an infrared light onto at least a part of the object and at least a part of the environment, collecting the infrared light reflected by at least the part of the object and at least the part the environment as a two-dimensional depth data sequence of the video sensor, computing the motion of the object by utilizing the two-dimensional depth data sequence, and controlling the light-emitting unit to change an attribute of the output light if the motion of the object complies with a predetermined condition.