An image capturing device includes an image capturing module, an image processing module coupled to the image capturing module, a comparing module, and an activating module. The image capturing module is capable of capturing images of an object including a pair of sequential pre-images and a final image of the object. The image processing module is capable of determining a movement of the object in the pair of sequential pre-images. The comparing module determines whether the movement of the object is within the range of a pre-determined movement tolerance stored in the comparing module and is capable of outputting a first trigger signal if the movement of the object is within the range of the pre-determined movement tolerance. The activating module receives the first trigger signal and activates the image capturing module to capture the final image of the object according to the first trigger signal.