Uniformity of appearance is a critical fabric property. Variation in color between and within fabric lots is a major problem whose control is complex, encompassing all stages of manufacturing, from fiber extrusion to fabric finishing. The visual evaluation currently used in fabric inspection for color variations is unsatisfactory, particularly in the characterization of the defect. To investigate this problem, researchers surveyed the responses of observers to color defects using standard psychophysical methods. In the survey, the observers were tested for variations in their perception of a stripe depending on its width and for the types of features observed in parallel arrays of stripes with known random variances of luminance or luminous reflectance. The researchers established the minimal conditions for finding a Cornsweet-Craik-O'Brien illusion in an array of yarns. 29 refs.