TRAFFIC SIGNAL LIGHT DETECTION THROUGH SUNGLARE FILTERS OF DIFFERENT Q FACTORS

Recent guides for use of sunglare protection filters have introduced t he concept of Q factors as a measure of colour appearance distortion i n viewing traffic signal lights. The adoption of Q factor values was a pparently arbitrary and not firmly based on experimental data. The man ner in which changes in Q factor affect colour perception and detectio n of signal lights has been measured and shows that detection threshol ds vary with the Q factor in a manner that can only partly be explaine d, but that is not independent of the colour of the signal as assumed in the guides. (C) 1997 John Wiley & Sons, Inc.