1. A method for detecting the movement of an image sensor according to a first, second, third, and fourth frame, captured sequentially by the image sensor, comprising the following steps: selecting a first captured image region in the first frame; selecting a first corresponding region to match the first captured image region in the second frame, wherein the first corresponding region shifts in a predetermined direction relative to the first captured image region; selecting a second captured image region in the third frame, wherein the second captured image region shifts in a direction opposite to the predetermined direction relative to the first captured image region; selecting a second corresponding region to match the second captured image region in the fourth frame; and determining the movement of the image sensor according to the second captured image region and the second corresponding region.