The present disclosure provides a switch, which includes a first input port, a second input port, an output port and a control circuit. The output port outputs image data received by the first input port. The control circuit receives a first electrical characteristic and a second electrical characteristic from the first input port and the second input port respectively, and changes a third electrical characteristic of the output port when the second electrical characteristic is different from the first electrical characteristic, and then the output port outputs image data received by the second input port.