1. A scanner, comprising: a processor; a scanning scope determining module having a scanning scope determining unit, coupled to the processor and determining a scanning scope; a scanning unit coupled to the processor and scanning an object to obtain an image file; and a storing unit coupled to the processor and storing the image file; wherein the scanning scope determining module further comprises a sensing element sensing the scanning scope determining unit so as to implement a real-time image auto-cutting function; and wherein the real-time image auto-cutting function processes the image file according to the scanning scope determined by the scanning scope determining unit when the scanning unit is scanning the object.