1. A method for improving image sharpness, comprising the following steps: (a) labeling each of pixels in an image as one of an edge/texture type and a non-edge/texture type; (b) classifying each of the pixels that are labeled as the edge/texture type as one of a border point type, a transition point type, and a peak point type; and (c) using a shrinking/expanding filter to filter the pixels of the border point type, and subsequently using a high boost filter to first filter the pixels of the peak point type and then filter the pixels of the transition point type to sharpen the image.