1. A method for thresholding image data comprising the steps of: generating a histogram of an image said histogram including histogram elements representative of a count of pixel elements of said image at predetermined intensities; computing a median of distribution of the image by summing the histogram elements until a half sum of a total of all pixels is reached; computing extremes of said distribution; determining the skew of said distribution from the relative position of said median with respect to said extremes to determine the color of the image background; determining a width of distribution of image background and defining an edge between background and foreground regions of the image by determining a point located between the median and the background extreme to be at a distance equal to half the distance between the median and the foreground color extreme, the edge point being used as a base for calculating a sequence of threshold levels; and determining said sequence of threshold levels in a foreground region of said histogram by establishing a plurality of points differentially spaced along the distance between said edge point and said foreground color extreme.