Psychophysicalexperimentsinspire a more complete analysis of the effect of quantization on a modified version of the histogram indexing method of object recognition. We derivean equationthat describeshow the amount of quantization and number of featureskept affectsrecognitionaccuracy. The equation shows that quantizationfrom 224colors to 15 colors has a negligible effect on accuracy. A simulation shows that large numbers of objects cause a corresponding decrease in accuracy, but that keeping more features can increase the accuracy even for massive quantization. An object recognitionexperimentwith real data shows dramaticallybetter results when quantization is used, indicating that massive color quantizationcan providesome invariance to lightingconditions.
Signe Redfield, John G. Harris