1. A binary image downsampling method, comprising: generating a gray-scale image from a binary image having a background and one or more foreground portions; locating skeleton pixels in the one or more foreground portions; manipulating values of certain foreground pixels in the gray-scale image such that the differences between the values of the skeleton pixels and the background pixels become more significant; downsampling the gray-scale image with the manipulated values of the certain foreground pixels; and generating a downsampled binary image from the downsampled gray-scale image.