INTERNAL INSPECTION METHOD FOR HOLLOW PATH

PROBLEM TO BE SOLVED: To enable judgment of whether the inside is abnormal or not by fuzzy reasoning from a measured data of feature quantities such as area or circumferential length as measured from a binary coded image by receiving light reflected irregularly even in a bent hollow path accurately. SOLUTION: In an inspection to determine whether the inside of an object 1 to be inspected is abnormal or not having a bent hollow path 4, diffusing light Lb is projected from an inlet of a path 4. The light passed being reflected irregularly through the path 4 is received by a specified image pickup means 9 on a two-dimensional plane at an outlet of the path to take an image. Then, the image taken is binary coded to extract a binary coded image involved in the inspection while the binary-coded image undergoes an image processing to measure feature quantities of the image. The goodness of fit of a measured data obtained for the normal data is judged by fuzzy reasoning to examine whether the inside of the hollow path 4 is abnormal or not.