Gesture sensing device and method of sensing three-dimensional gestures

A three-dimensional image sensing device includes a light source, a sensing module, and a signal processing module. The sensing module includes a pixel array, a control unit, and a light source driver. The light source generates flashing light with K times alternating current frequency or a predetermined frequency. The pixel array samples the flashing light to generate a sampling result. The control unit executes an image processing on the sampling result to generate a spectrum corresponding to the sampling result. The light source driver drives the light source according to the K times alternating current frequency or the predetermined frequency. The signal processing module generates and outputs the K times alternating current frequency according to the spectrum, or outputs the predetermined frequency to the light source driver, and generates depth information according to a plurality of first images when the light source is turned on and a plurality of second images when the light source is turned off incl