1. A method comprising: (a) computing color ratios from red, green and blue (R,G,B) values for a first pixel; (b) determining if the color ratios are out of a range by comparing the ratios to maximum and minimum values; (c) if the color ratios are out of the range, skipping the first pixel and performing (a) and (b) for a second pixel; (d) if the color ratios are in range, quantizing the color ratios to fixed point integers; (e) looking up the fixed point integers in a table to find a cluster index; (f) determining if the cluster index is zero; (g) if the cluster index is zero, performing (a) and (b) for the second pixel; and (h) if the cluster index is greater than zero, incrementing color ratio sums associated with the cluster index and incrementing a number of pixels associated with the cluster index.