Adaptive Surface Fitting for Inspection of FPD Devices Using Multilevel B-spline Approximation

Abstract

This paper proposes a surface fitting algorithm for inspection of flat panel display(FPD) based on multilevel B-spline approximation(MBA). FPD devices have non-uniform background, and shape and intensity of defects are very various. MBA is useful algorithm for surface fitting but it is sensitive to number of control lattices. As level increases, details of original image can be reconstructed. To detect defect, defective area must not be well-reconstructed. In this paper, we propose a level decision method of MBA for FPD. After process of each level, we decide whether stop to increase level of MBA or not with simple distance measure. Experimental result shows that our proposed method makes to detect defects easy.

Defect Detection of TFT-LCD Image Using Adapted Contrast Sensitivity Function and Wavelet Transform

“…Hence, to help separates the Muras, we must flatten the background signal, reduce the random noise and enlarge the Mura signal. The most effective and useful approach to facilitating Mura segmentation is backgroundsignal flattening using polynomial approximation (PA) [4] or B-splines [5]. PA or B-splines seek the best-fitting surface or the plane that best describes the shape of the signal at a minimum mean-square-error point.…”

Sequential Defect Detection According to Defect Possibility in TFT-LCD Panel Image

“…획득된 TFT-LCD 패널 영상은 BLU(Back Light Unit)로 인한 불균일한 휘도 분포와 여러 가지 환경적인 요인으로 잡음 성분이 혼재되어 있다. 이러한 불균일한 휘도 분포와 잡음 성분은 TFT-LCD 결함 검 출에서 과검출이나 미검출의 요인으로 작용하여 결함 검출의 견실성을 보장할 수 없다 [5] . 특히 한도 결함의 경우 배경과 결함의 휘도차가 매우 작기 때문에 일반적 인 임계화 방법으로 결함을 신뢰성 있게 검출하는데 어 려움이 있다.…”

Segmentation of Defective Regions based on Logical Discernment and Multiple Windows for Inspection of TFT-LCD Panels

“…기존 연구되어온 공간영역 상에서 분할방법으로 는 배경잡음을 제거하거나 결함을 강조하기 위한 영 역 성장 기법 [4][5][6], 배경신호를 평활화하는 B-스프 라인 기법 [7,8], 다항식 근사 기법 [9], MMTF(Modified Modulation Transfer Function)기법 [10]…”