Directional Filter Bank for NDE Image Segmentation

This paper introduces a Directional Filter Bank (DFB) for segmentation of C-Scan images from fiber-reinforced composites. The DFB is a two-channel decomposition employing the Quincunx sampling matrix and the Diamond Half Band filter pair. The incident ultrasonic field on a fiber-reinforced composite is backscattered by the fibers leading to the appearance of a characteristic pattern (oriented along the fiber direction) in the C-Scan image. The fiber pattern can cloud the defects, such as delaminations etc, thus making their detection difficult. The DFB is a sub-band coding technique that has been applied to segment the fiber pattern from the defect features in the C-Scan image of the composite