Patent ID: 8737682

Claim:
A pipe thickness measuring device comprising: a luminance profile obtaining unit which obtains luminance profiles in a direction crossing a pipe to be measured from radiographic images of the pipe; an outer diameter point detecting unit which detects outer diameter points of the pipe based on the obtained luminance profiles; a region setting unit which sets a predeteimined region inside two of the outer diameter points of the pipe detected by the outer diameter point detecting unit; and an inner diameter point detecting unit which detects inner diameter points of the pipe based on a luminance profile corresponding to the set predetermined region from among the luminance profiles obtained by the luminance profile obtaining unit, wherein the outer diameter point detecting unit includes a normalizing unit which normalizes the luminance profile obtained by the luminance profile obtaining unit, a first order differential profile calculating unit which calculates a first order differential profile by first order differentiating the normalized luminance profile, a noise removing unit which removes noise components from the first order differential profile, a second order differential profile calculating unit which calculates a second order differential profile by differentiating the first order differential profile from which the noise components are removed, a zero cross region setting unit which detects a zero cross point of the calculated second order differential profile and sets a zero cross region near the zero cross point, an approximate curve calculating unit which calculates an approximate curve by approximating a second order differential profile of the set zero cross region with a predetermined function, and a detecting unit which detects the outer diameter points each based on a zero cross point of the calculated approximate curve.