Abstract
In order to consider visual inspection utilizing peripheral vision, this paper examines the differences of defects that affect the defects detection. As the features of defects, the size, lightness and color are experimental factors. As the result, the smaller size of the defects shows that the defect detection is difficult. In addition, it is obtained experimentally that the difference of lightness and color between the background and defects can be evaluated by the luminance. The difference of lightness between the background and defects is smaller, the defect detection is more difficult. Moreover, the index of difficulty to detect defects is proposed by multiplying the area of the defect to the luminance contrast, the validity of the index is revealed experimentally.
