1. An auto-focusing method comprising: creating focus values for an image, each focus value corresponding to a distance between a lens and a subject, and generating a focus graph of the focus values; comparing the focus graph with at least one of a point light source reference graph and a non-point light source reference graph; determining whether the focus graph corresponds to a point light source reference graph or a non-point light source reference graph based on comparison result; if the focus graph corresponds to the point light source reference graph, determining a minimum point on the focus graph as a focus value of a focused image; and if the focus graph corresponds to the non-point light source reference graph, determining a maximum point on the focus graph as the focus value of the focused image.