1. An image calibrating method for stitching adjacent images, the image calibrating method comprising: calculating contrast values of a plurality of images; comparing the contrast values to set the image with maximal contrast value as a reference image, wherein the other images of the plurality of images are defined as target images; calculating probability distribution information of the reference image and the target images respectively; and obtaining a transform function according to the probability distribution information of the reference image and the target images for pixel adjustment of the target images.