Thresholding gray-scale images to produce bitonal images. In one example
embodiment, a method for thresholding a gray-scale image to produce a
bitonal image includes several acts. First, a first portion of gray-scale
pixels of the gray-scale image are thresholded based on a global
threshold and edge strength information. Next, a second portion of the
gray-scale pixels are thresholded based on the global threshold and local
pixel information. Finally, a third portion of the gray-scale pixels are
thresholded based on a local threshold.