Color image processing was used to classify the impurities in nylon 66 that fluoresce when exposed to ultraviolet light. The hue value determined from digitized color images was found to correlate well to the color of the fluorescence as seen by the naked eye. Digital image processing is advantageous over visual observation because it removes the subjectivity from the classification process, and is a relatively simple and inexpensive method compared to other spectroscopic techniques. The hue values of the impurities may provide a quantitative data base that could lead to process improvements.