An image detecting method, comprising: controlling a synchronizing controller to transmit a first activating signal to a light source controller; controlling the light source controller to control at least one light source to generate a predetermined radiating pattern, and controlling the light source controller to transmit back a first responding signal to the synchronizing controller when the light source controller receives the first activating signal; and controlling an image sensor to start an image detecting when the synchronizing controller receives the first responding signal.
展开▼