Color Models for Outdoor Machine Vision

This study develops models for illumination and surface reflectance for use in outdoor color vision, and in particular for predicting the color of surfaces under outdoor conditions. Existing daylight and reflectance models have limitations that reduce their applicability in outdoor contexts. This work makes three specific contributions: (i) an explanation of why the current standard CIE daylight model cannot be used to predict the color of light incident on outdoor surfaces, (ii) a model (table) of the measured color of daylight for a broad range of sky conditions, and (iii) a simplified adaptation of the dichromatic reflectance model for use with the developed daylight model. A series of experiments measure the accuracy of the daylight and reflectance models, and their applicability to outdoor color vision applications, by predicting the colors of surfaces in real images. c © 2001 Elsevier Science (USA)