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Digital image acquisition for x-ray image processing
In this article some basic aspects of the hardware and software adaption hu real time image analysis of weld radiographs are discussed and an optimized image analysis strategy is presented. 40147
Hedengren, K.H.; McCary, R.O.; Young, J.D.
Use of imaging techniques for eddy current NDE Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A+ pp. 357-366. Edited by D . D . T h o m p s o n and D.E.Chimenti, Plenum Press, 1988. New stringent inspection requirements, imposed by the United States Government, demand detection and/or characterization of very small surface fatigue cracks in rotating parts of aircraft engines. These requirements cannot be met using the traditional approach to eddy current testing. The work described in this paper is aimed at finding surface penetrating fatigue cracks on the order of Ill mils long by 5 mils deep. To accomplish this goal, eddy current NDT is addressed from a systems point of view, based on creation of images. Image processing techniques are used to improve probability of detection of small flaws and to extract quantitative information. Images also are used to evaluate system performance and to characterize eddy current probes. 40132
Zheng, Y.; Basart, J.P.
NDE X-ray modeling and adaptive fltering considering correlated noise Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 813-820. Edited by D.D. T h o m p s o n and D . E Chimenti, Plenum Press, 1988. In this work, an adaptive Kalman filtering technique is developed to remove noise fluctuation caused by film-grain noise, quantum fluctuation, and film dirt of industrial-radiographic X-ray images. With this technique, knowledge of a radiographic X-ray image forming mechanism is employed to obtain AutoRegressive (AR) models of an image. The AR representation of an image is written in a state-space form and then incorporated into a Kalman filter that enhances an image by optimally separating a noise-free image process from a noise process. Since the image model of this technique closely represents a real image, a better estimation of an image can be obtained than that of many other methods. Since the recursive property of the Kalman filter is an advantage; the execution speed of this method is fast. The computation time is comparable to that of many simple smoothing algorithms. 40129
Bell, Z.W.
Evaluation of thresholding heuristics useful for automated fiimless radiography Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 739-746. Edited by D.D. T h o m p s o n and D.E. Chimenti, Plenum Press, 1988. In developing a filmless radiographic inspection system an automatic evaluation process will incorporate the heuristics used by human radiographers to evaluate exposed film. Brightness (gray-level in a digital radiograph) and texture are two of the cues used by humans to separate regions-of-interest from the background in an image. Defects appear as areas on the film whose optical density differs from some reference value. The human radiographer uses gray-level thresholding and some spatial averaging to discriminate between background and defect on a film. Both processes are readily applied to digital radiographs by using an image processor, 40126
Russell, S.F.
Digital image acquisition for x-ray image processing Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 713-722. Edited by D.D. T h o m p s o n and D.E. Chimenti, Plenum Press, 1988. Digital image analysis applied to the x-ray inspection of weldments and castings is becoming a practical and reasonable-cost technology. The image analysis research being conducted by the Center for NDE at Iowa State University is focussed on developing image processing algorithms that will improve the visual quality of x-ray images. The subsequent noise reduction and contrast enhancement make the images easier to analyze and help reduce operator fatigue. Although real-time x-ray image acquisition and analysis is the ultimate goal of much of the industry, the need still exists for digital analysis of radiographs. Because of this, the Center has decided to begin its effort using radiographs. In this paper the technical issues involved in obtaining the best possible digital images from radiographs are discussed. The goal of this paper will be to describe the process of digital image acquisition and discuss techniques that minimize these undesirable characteristics. 39921
Cotter, D.J.; Koenigsberg, W.D.; Pasto, A.E.; Bowen, L.J.
voids. A digital image processing system was used to obtain data on size. shape. and location of the voids. Failure stress was measured for the bars and then related to the stress at the flaw location by an elemental analysis. Fractography was also performed on the broken bars. The Weibull modulus of the NDE rejected samples was 3.9 compared with 13.0 for the NDE accepted samples 39918
Hentea, T.; Ellingson, W.A.; Roberts, R.A.; Kriz, R.J.
Deblurring of conventional tomography images with applications to the NDE of advanced ceramics Ceramic Engineering and Science Proceedings, Vol. 9, Nos. 9-10, pp. 1471-1481 (1988). 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2, Sep.-Oct. 1988. Low-cost X-ray tomographic imaging methods may be useful for detecting defects in structural ceramics. Conventional film-based tomography systems, although potentially inexpensive, produce images that are affected by blurring caused by the structure of the object above and below the tomographic plane of interest, The blur can be removed by using digital image processing techniques. Three methods for deblurring images of ceramic specimens will be discussed, inverse filtering, iterative approximation, and multiplane approximation. 39916
Xu, S.B.; Lu, W.X.
Surface reconstruction of 3D objects in computerized tomography Computer Vision, Graphics and Image Processing, Vol. 44, No. 3, pp. 27(/-278 (Dec. 1988) This paper deals with the problem of surface reconstruction of 3- dimensional boundaries in a family of slice images in computerized tomography (CT). Its mathematical formulation is first given, in which it is considered as a problem of functional minimization. Next, the corresponding Euler partial differential equation is derived and it is then solved by the finite difference method. Numerical solution can be found by using the iterative method. 39910
Lindegaard-Andersen, A.; Vedel, T.; Jeppesen. L.; Gottlieb,
B. Film-based X-ray tomography combined with digital image processing: investigation of an ancient pattern-welded sword N D T International, Vol. 21, No. 6, pp. 407-410 (Dec. 1988) Film-based X-ray tomography and digital image processing have been used to investigate an inhomogeneous object of non-circular cross-section. The feasibility of using digital image processing to compensate for the poor contrast resolution inherent in film-based tomography has been demonstrated. 39854
West, G.A.W.; Ellis, T.J.; Finkelstein, L.
Image processing and understanding for automatic inspection Transactions of the Institute of Measurement and Control, Vol. 10, No. 5, pp. 265-272 (Oct.-Dec. 19881 This paper reviews the techniques and methodologies that have been proposed for industrial applications of image processing. The application considered here is related to its use in automatic inspection, where techniques for the detection and identification of manufacturing defects are used to support decisions for product quality control. It describes fundamental principles and techniques that have become apparent over the past 20 years giving examples mainly from research performed at the Measurement and Instrumentation Centre. 39755
lkeda, Y.; Sakai, H.; Ohkubo, K.; Matsumoto, G.
Neutron computed tomography with a high-speed image processor Materials Evaluation, Vol. 46, No. l l , pp. 1471-1476 (Oct. 1988) Neutron computed tomography (NCT) using real-time neutron radiography and an electronic image-processing technique is described in this paper. A high-speed image processor, TOSPIX-II, was used for image inputting and reconstruction. Including pre-and post-image processing, 1.0 mm resolution of CT images was obtained with 50 to 100 projection data, and the required computing time for reconstruction was about 20 rain. It was recognized that by further improvement of the neutron television system and use of some higher-grade central processing unit (CPU), the resolution will be greatly improved and the requirement for CPU time will be reduced. 39748
Olsen, R.
More than just a pretty picture: real-time X-ray image enhancement in the electronics industry Materials Evaluation, Vol. 46, No. 11, pp. 1403-1408 (Oct. 1988) Real time X-radiographic systems are now available to the electronics industry at much reduced cost and with sufficient power, adequate resolution and image processing capabilities. Productivity and effectiveness can both be improved using this technique and pseudocolour can be used to enhance contrast and identify defects more easily and so improve non destructive testing. The capabilities and modus operandi of one commercially +wailable system is described.
Working Group of Commission V of the International Institute of Welding (IlW)
Improving the reliability of high-performance ceramics using nondestructive evaluation
39742
Ceramic Engineering and Science Proceedings, Vol. 9, Nos. 9-10, pp. 1503-1516 (1988). 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2, Sep.-Oct. 1988. Results are presented from a program to improve the reliability of advanced silicon nitride ceramics through the use of nondestructive evaluation. A large quantity of silicon nitride test bars was inspected by mierofocus radiography. In total, 76 bars were rejected because they contained major naturally occurring
X-ray real-time imaging (radioscopy) for weld inspection: IIW 4th progress report
170
British Journal of Nondestructive Testing, Vol. 30, No+ 6, pp. 400-402 (Nov. 1988) Automated image interpretation in X-ray real-time inspection of welds is a complex field of pattern recognition. Real-time conditions and system characteristics require a powerful hardware configuration and special image
NDT International June 1990
Hedengren, K.H.; McCary, R.O.; Young, J.D.
Use of imaging techniques for eddy current NDE Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A+ pp. 357-366. Edited by D . D . T h o m p s o n and D.E.Chimenti, Plenum Press, 1988. New stringent inspection requirements, imposed by the United States Government, demand detection and/or characterization of very small surface fatigue cracks in rotating parts of aircraft engines. These requirements cannot be met using the traditional approach to eddy current testing. The work described in this paper is aimed at finding surface penetrating fatigue cracks on the order of Ill mils long by 5 mils deep. To accomplish this goal, eddy current NDT is addressed from a systems point of view, based on creation of images. Image processing techniques are used to improve probability of detection of small flaws and to extract quantitative information. Images also are used to evaluate system performance and to characterize eddy current probes. 40132
Zheng, Y.; Basart, J.P.
NDE X-ray modeling and adaptive fltering considering correlated noise Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 813-820. Edited by D.D. T h o m p s o n and D . E Chimenti, Plenum Press, 1988. In this work, an adaptive Kalman filtering technique is developed to remove noise fluctuation caused by film-grain noise, quantum fluctuation, and film dirt of industrial-radiographic X-ray images. With this technique, knowledge of a radiographic X-ray image forming mechanism is employed to obtain AutoRegressive (AR) models of an image. The AR representation of an image is written in a state-space form and then incorporated into a Kalman filter that enhances an image by optimally separating a noise-free image process from a noise process. Since the image model of this technique closely represents a real image, a better estimation of an image can be obtained than that of many other methods. Since the recursive property of the Kalman filter is an advantage; the execution speed of this method is fast. The computation time is comparable to that of many simple smoothing algorithms. 40129
Bell, Z.W.
Evaluation of thresholding heuristics useful for automated fiimless radiography Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 739-746. Edited by D.D. T h o m p s o n and D.E. Chimenti, Plenum Press, 1988. In developing a filmless radiographic inspection system an automatic evaluation process will incorporate the heuristics used by human radiographers to evaluate exposed film. Brightness (gray-level in a digital radiograph) and texture are two of the cues used by humans to separate regions-of-interest from the background in an image. Defects appear as areas on the film whose optical density differs from some reference value. The human radiographer uses gray-level thresholding and some spatial averaging to discriminate between background and defect on a film. Both processes are readily applied to digital radiographs by using an image processor, 40126
Russell, S.F.
Digital image acquisition for x-ray image processing Review of Progress in Quantitative Nondestructive Evaluation, Williamsburg, Virginia (United States), 22-26 Jun. 1987. Vol. 7A, pp. 713-722. Edited by D.D. T h o m p s o n and D.E. Chimenti, Plenum Press, 1988. Digital image analysis applied to the x-ray inspection of weldments and castings is becoming a practical and reasonable-cost technology. The image analysis research being conducted by the Center for NDE at Iowa State University is focussed on developing image processing algorithms that will improve the visual quality of x-ray images. The subsequent noise reduction and contrast enhancement make the images easier to analyze and help reduce operator fatigue. Although real-time x-ray image acquisition and analysis is the ultimate goal of much of the industry, the need still exists for digital analysis of radiographs. Because of this, the Center has decided to begin its effort using radiographs. In this paper the technical issues involved in obtaining the best possible digital images from radiographs are discussed. The goal of this paper will be to describe the process of digital image acquisition and discuss techniques that minimize these undesirable characteristics. 39921
Cotter, D.J.; Koenigsberg, W.D.; Pasto, A.E.; Bowen, L.J.
voids. A digital image processing system was used to obtain data on size. shape. and location of the voids. Failure stress was measured for the bars and then related to the stress at the flaw location by an elemental analysis. Fractography was also performed on the broken bars. The Weibull modulus of the NDE rejected samples was 3.9 compared with 13.0 for the NDE accepted samples 39918
Hentea, T.; Ellingson, W.A.; Roberts, R.A.; Kriz, R.J.
Deblurring of conventional tomography images with applications to the NDE of advanced ceramics Ceramic Engineering and Science Proceedings, Vol. 9, Nos. 9-10, pp. 1471-1481 (1988). 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2, Sep.-Oct. 1988. Low-cost X-ray tomographic imaging methods may be useful for detecting defects in structural ceramics. Conventional film-based tomography systems, although potentially inexpensive, produce images that are affected by blurring caused by the structure of the object above and below the tomographic plane of interest, The blur can be removed by using digital image processing techniques. Three methods for deblurring images of ceramic specimens will be discussed, inverse filtering, iterative approximation, and multiplane approximation. 39916
Xu, S.B.; Lu, W.X.
Surface reconstruction of 3D objects in computerized tomography Computer Vision, Graphics and Image Processing, Vol. 44, No. 3, pp. 27(/-278 (Dec. 1988) This paper deals with the problem of surface reconstruction of 3- dimensional boundaries in a family of slice images in computerized tomography (CT). Its mathematical formulation is first given, in which it is considered as a problem of functional minimization. Next, the corresponding Euler partial differential equation is derived and it is then solved by the finite difference method. Numerical solution can be found by using the iterative method. 39910
Lindegaard-Andersen, A.; Vedel, T.; Jeppesen. L.; Gottlieb,
B. Film-based X-ray tomography combined with digital image processing: investigation of an ancient pattern-welded sword N D T International, Vol. 21, No. 6, pp. 407-410 (Dec. 1988) Film-based X-ray tomography and digital image processing have been used to investigate an inhomogeneous object of non-circular cross-section. The feasibility of using digital image processing to compensate for the poor contrast resolution inherent in film-based tomography has been demonstrated. 39854
West, G.A.W.; Ellis, T.J.; Finkelstein, L.
Image processing and understanding for automatic inspection Transactions of the Institute of Measurement and Control, Vol. 10, No. 5, pp. 265-272 (Oct.-Dec. 19881 This paper reviews the techniques and methodologies that have been proposed for industrial applications of image processing. The application considered here is related to its use in automatic inspection, where techniques for the detection and identification of manufacturing defects are used to support decisions for product quality control. It describes fundamental principles and techniques that have become apparent over the past 20 years giving examples mainly from research performed at the Measurement and Instrumentation Centre. 39755
lkeda, Y.; Sakai, H.; Ohkubo, K.; Matsumoto, G.
Neutron computed tomography with a high-speed image processor Materials Evaluation, Vol. 46, No. l l , pp. 1471-1476 (Oct. 1988) Neutron computed tomography (NCT) using real-time neutron radiography and an electronic image-processing technique is described in this paper. A high-speed image processor, TOSPIX-II, was used for image inputting and reconstruction. Including pre-and post-image processing, 1.0 mm resolution of CT images was obtained with 50 to 100 projection data, and the required computing time for reconstruction was about 20 rain. It was recognized that by further improvement of the neutron television system and use of some higher-grade central processing unit (CPU), the resolution will be greatly improved and the requirement for CPU time will be reduced. 39748
Olsen, R.
More than just a pretty picture: real-time X-ray image enhancement in the electronics industry Materials Evaluation, Vol. 46, No. 11, pp. 1403-1408 (Oct. 1988) Real time X-radiographic systems are now available to the electronics industry at much reduced cost and with sufficient power, adequate resolution and image processing capabilities. Productivity and effectiveness can both be improved using this technique and pseudocolour can be used to enhance contrast and identify defects more easily and so improve non destructive testing. The capabilities and modus operandi of one commercially +wailable system is described.
Working Group of Commission V of the International Institute of Welding (IlW)
Improving the reliability of high-performance ceramics using nondestructive evaluation
39742
Ceramic Engineering and Science Proceedings, Vol. 9, Nos. 9-10, pp. 1503-1516 (1988). 12th Annual Conference on Composites and Advanced Ceramic Materials, Part 2 of 2, Sep.-Oct. 1988. Results are presented from a program to improve the reliability of advanced silicon nitride ceramics through the use of nondestructive evaluation. A large quantity of silicon nitride test bars was inspected by mierofocus radiography. In total, 76 bars were rejected because they contained major naturally occurring
X-ray real-time imaging (radioscopy) for weld inspection: IIW 4th progress report
170
British Journal of Nondestructive Testing, Vol. 30, No+ 6, pp. 400-402 (Nov. 1988) Automated image interpretation in X-ray real-time inspection of welds is a complex field of pattern recognition. Real-time conditions and system characteristics require a powerful hardware configuration and special image
NDT International June 1990