1. A method for thresholding a gray-scale image to produce a bitonal image, the method comprising the acts of: thresholding a first portion of gray-scale pixels of the gray-scale image based on a global threshold and edge strength information; thresholding a second portion of the gray-scale pixels based on the global threshold and local pixel information; and thresholding a third portion of the gray-scale pixels based on a local threshold.