A system for detection of internal log defects by computer analysis of axial CT images

The paper presents a system for detection of some important internal log defects via analysis of axial CT images. Two major procedures are used. The first is the segmentation of a single computer tomography (CT) image slice which extracts defect-like regions from the image slice, the second is correlation analysis of the defect-like regions across CT image slices. The segmentation algorithm for a single CT image is basically a complex form of multiple thresholding that exploits both the prior knowledge of wood structure and gray value characteristics of the image. The defect-like region extraction algorithm first locates the pith, groups the pixels in the segmented image on the basis of their connectivity and classifies each region as either a defect-like region or a defect-free region using shape, orientation and morphological features. Each defect-like region is classified as a defect or non-defect via correlation analysis across corresponding defect-like regions in neighboring CT image slices.