| 摘要 |
PURPOSE:To detect a defect highly precisely without being affected by a processing by smoothing characteristic data, by estimating a change in a characteristic due to a processing applied to a material to be inspected, and by detecting the change on the basis of a differential between the estimated change and original data. CONSTITUTION:A density signal picked up by a TV camera 61 is inputted to an image processing unit 3 and a monitor TV 8 by a switching unit 7. When the camera 61 picks up an image of the surface of a steel plate having a flaw, the unit 3 prepares a differential image by using said image and a smoothed image and further subjects the differential image to binary-coding, so that a binary-coded image be obtained. Accordingly, data corresponding only to a flaw varying at a high frequency are obtained from the differential image, and by subjecting these data to binary-coding, data specifying the position of the flaw in a sub-scanning direction are obtained. By detecting a change in the physical characteristic of a material to be inspected, in this way, a defect can be detected highly precisely without being affected by a processing applied to the material to be inspected. |
