1. A method for image auto-selection comprising the steps of: providing a characteristic value database stored in a storage unit of a computer system, wherein the characteristic value database stores at least a predetermined characteristic value; capturing, using an image capturing unit of the computer system, a plurality of images in a predetermined period; obtaining, using a processing unit of the computer system, a first characteristic value of each of the images, respectively, and calculating a first distance of each of the images according to the first characteristic value of each of the images and the predetermined characteristic value; obtaining, using the processing unit, a second characteristic value from each of the images, respectively, calculating a second distance of each of the images according to the second characteristic value of each of the images and each predetermined characteristic value, calculating a third distance of each of the images according to the first distance and the second distance; and selecting, using the processing unit, at least an image from the images according to the third distance of each of the images.