1. An image processing device, for receiving a plurality of second-resolution images generated by enlarging a plurality of first-resolution images, wherein one of the second-resolution images is a target image and the rest second-resolution images are a plurality of non-selected images; the image processing device comprising: an image correcting module, estimating a plurality of local motions and a plurality of global motions of the non-selected images relative to the target image, and performing a plurality of motion corrections on the non-selected images so as to generate a plurality of corrected images; an object-motion detection module, coupled to the image correcting module, and judging whether or not the difference between each of the local motions and the corresponding global motion is greater than a threshold value so as to generate a plurality of object-motion indicators; and an image blending module, coupled to the object-motion detection module, and performing an arithmetic operation on each pixel of the target image and each pixel of the corrected images according to the object-motion indicators so as to generate a third-resolution image, wherein the resolution of the third-resolution image is higher than the resolution of the second-resolution images.