An image scanning method includes pre-scanning a first document to generate a first original image according to the first document; adjusting parameter settings of the first original image to generate and store a plurality of pre-view images corresponding to different sets of parameters; pre-scanning a second document to generate a second original image according to the second document; and scanning the second document to generate a plurality of scanning images according to the different sets of parameters of the pre-view images. The parameter settings of the first original image include brightness, shadow, and contrast settings.