Evaluation of TFT-LCD defects based on human visual perception

In this paper, we propose an evaluation method of the TFT-LCD defect. Although several detection methods based on image processing techniques detect TFT-LCD defects, the majority of them are un-noticeable to the human eye because of the low contrast and unclear defect boundary. Therefore, to minimize the yield loss, all defects are re-inspected by visual inspector. The proposed method evaluates each defect and gives a corresponding level that objectively agrees with the assessment of a group of inspectors. The basic idea is to use the characteristics of the human visual perception in the evaluation. Crucial features of the defect were selected and the human perception degree was approximated through the regression analysis. In the process, we define the “just noticeable difference surface” (JND) and evaluate the level of defect as the distance from a defect consisting of a vector of selected features to the JND.