Wavelet based Uneven Illumination Compensation for Defect Detection of Flat Panel Display

S.J. Kim, N.Y. Kim, B.G. Lee, and J.J. Lee (Korea)


Defect detection, flat panel display, illumination compensation, segmentation


FPD(Flat panel displays) are becoming widely acceptable and popular as display devices growing at a rapid pace and making it a promising investment opportunity. Display quality is part of the final FPD inspection process prior to shipping. FPD devices have non-uniform background intensity, and shape and intensity of defects are very various. Due to the uneven illumination of panels it is difficult to detect the defects, Therefore this paper proposes a uneven illumination compensation method using wavelet based multi-resolution structure. This is first done by decomposing the image into multi-resolution levels and selecting some band frequency sub-bands by removing lower sub-bands and higher sub-bands corresponding to low varying signal and high frequency random noise, respectively, resulting in flat background images in reconstruction. A simple binary thresholding technique is then used to separate the defective regions from the restored image. Finally, blob analysis as post processing is carried out to get rid of false defects.

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