On connected filters in color image processing

A standard approach to extending gray-scale filters to color is the use of gray-scale filters on each of the red, green, and blue bands separately. This RGB component method, when applied to connected filters, causes the introduction of new colors into the image, which could lead to incorrect classification or analysis. We develop a method of applying connected filters to color images using rotation in the hue band of the hue-saturation-value (HSV) color space. The rotation shifts the discontinuity in hue such that the distance to the nearest k-means cluster mean is maximized and the histogram value is simultaneously minimized. When applied to the sample image set, the error from the RGB component approach is of the order of 10 times greater than that of our hue rotation approach. Additionally, our approach yields qualitatively improved images, with fewer new colors introduced than the RGB component method. (C) 2004 SPIE and IST.