Abstract
The physical property, expressing the state of stained outdoor road paved with ceramic tiles in valious settings from a visual point of view, was clarified. In other words, it was found that there was a strong correlation between the psychological scale created through a sensory test for measuring the degree of perceived stains and the changes of optical conditions from a virgin state to a stained state (average color difference and the maximum color difference which show an unevenness of apparent stains). In addition, from the relation between the evaluating scale for measuring the degree of stains and the above-mentioned physical property, a method of evaluation for the state of stains was expressed.
