PURPOSE: To rapidly, accurately execute identification of a defect, decision of a class, etc., by continuously processing an image signal on a surface of a material to be inspected to detect a malfunction, and selecting only the signal indicating the malfunction from an image memory to be processed.
CONSTITUTION: A malfunction detector 32 processes an image signal representing a surface of a material 10 (hot rolled steel plate) to be inspected and amplified by an amplifier 26 and fed by a band-pass filter to remove an illuminating irregularity and noise component, differentiates the signal to intensify a signal representing the malfunction, compares it with a predetermined threshold value, and sends a signal representing a position and an amplitude of the malfunction to an image transmitter 34. The transmitter 34 extracts only data representing the malfunction from the image data of an image memory 30, and sends it to an image processor 36. The processor 36 decides whether the malfunction of the surface of the plate 10 is a defect or not based on the data and decides, if it is the defect, its type, class and whether the same defect is continuously periodically detected or not, and displays a decided result on a CRT 38.
SONOBE OSAMU
MARUYAMA SATOSHI
DANKI RIYOUICHI
MORIYA SUSUMU
YOKOO MASAKAZU
