TFT-LCD mura defect detection using DCT and the dual-γ piecewise exponential transform

This paper proposes a mura defect detection method that is based on the discrete cosine transform and the dual-gamma piecewise exponential transform for thin-film transistor liquid crystal display panels. First, the background of the original image with mura defects is reconstructed by means of the discrete cosine transform, and the mura image is obtained by subtracting the reconstructed image from the original image. Second, the dual-gamma piecewise exponential transform method is proposed for suppressing residual background information and improving the contrast of the image. Finally, Otsu's method is adopted to segment the muras completely. The experimental results suggest that the proposed method effectively increases the low contrast of muras by at least 14 times compared to the traditional discrete cosine transform background reconstruction method and at least 2 times compared to the polynomial fitting method. In addition, the method improves the accuracy of mura defect identification, and the detection effect is stable for various non-uniform backgrounds. These results demonstrate that the proposed method has high accuracy and robustness.