Detection of Local Mura Defects in TFT-LCD Using Machine Vision

Machine vision is widely used in the field of defect inspection. Mura is a typical defect of LCD panel, appearing as local lightness variation with low contrast and blurry contour, so it is hard to be inspected with traditional thresholding or edge detection methods. This paper presents a machine vision Mura inspection method based on real Gabor filter. By selecting appropriate number of filtering scale and orientation, a set of real Gabor filter are formed and applied to the LCD images with defects. Then, through images fusion, all the sub-images from different channels are fused together and as a result, the global structurally textured backgrounds are eliminated and the local defects are preserved. As expected, the final binary images show the defects out. Experiments show that this method is suitable to the inspection of many types of Mura. Furthermore, it is insensitive to the rotation of image.