ウェーブレット変換によるプリント基板検査のためのECT画像処理

概要

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This paper presents an image processing method utilizing the wavelet transform (WT) for the inspection of printed circuit board (PCB) by using eddy-current testing (ECT) technique. First, undesired components in the ECT image, which degrade the precision of the defect-detection, are removed through two types of filtering operations (based on frequency and amplitude, respectively) utilizing discrete WT. Considering that the ECT measurement is carried out horizontally, the proposed method applies WT only along that direction. Then, to estimate the existence and position of the defect, a correlation-based comparison is made between two images: the one is derived from a reference PCB (nondefect) and the other is from the tested object. The effectiveness compared with conventional approach and problem of the proposed method is investigated through examples of disconnection models.
2001-03-10