한국지반공학회논문집 (Journal of the Korean Geotechnical Society)

  • 제27권11호
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  • Pages.93-101
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  • 2011
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  • 1229-2427(pISSN)
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  • 2288-646X(eISSN)
한국지반공학회 (Korean Geotechnical Society)
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X-ray micro-CT 이미지 내 패임 및 동심원상 화상결함 제거를 위한 이미지 보정 기법

Image Calibration Techniques for Removing Cupping and Ring Artifacts in X-ray Micro-CT Images

  • 정연종 (연세대학교 사회환경시스템공학부) ;
  • 윤태섭 (연세대학교 사회환경시스템공학부) ;
  • 김광염 (한국건설기술연구원) ;
  • 주진현 (한국건설기술연구원)
  • 투고 : 2011.09.28
  • 심사 : 2011.11.17
  • 발행 : 2011.11.30
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초록

X-ray micro-CT를 이용한 지반재료 내부 미세구조 및 공극구조의 정밀한 이미지 처리는 종종 이미지 내에 원천적으로 포함되는 화상결함으로 인해 제약된다. 본 논문에서는 X-ray micro-CT 이미지에 가장 일반적으로 나타나는 화상결함인 패임(영상 외곽과 중심부의 명암 차이) 및 동심원상(영상 중심으로부터 방사방향으로 연속적으로 나타나는 원)을 제거할 수 있는 이미지 보정 기법을 제시한다. 결함 제거는 좌표 변환법, 정규화 및 2차원 푸리에 변환에 의한 저역 통과 필터링 기법의 순차적 적용을 통해 이루어진다. 이미지 처리 기법의 효과를 다공성 현무암의 CT 이미지에서 화상결함들을 제거하고 이진화 후 적층하여 3차원 공극 구조를 추출하는 과정을 통해 설명하였다. 패임 및 동심원상 결함을 제거한 이미지와 원본 이미지의 비교 결과 결함 제거는 대상 재료 공극률의 과대평가를 방지할 수 있으며, 따라서 화상결함의 적절한 보정은 X-ray CT의 지반재료 적용 시 필수적인 과정으로 판단된다.

High quality X-ray computed microtomography (micro-CT) imaging of internal microstructures and pore space in geomaterials is often hampered by some inherent noises embedded in the images. In this paper, we introduce image calibration techniques for removing the most common noises in X-ray micro-CT, cupping (brightness difference between the periphery and central regions) and ring artifacts (consecutive concentric circles emanating from the origin). The artifacts removal sequentially applies coordinate transformation, normalization, and low-pass filtering in 2D Fourier spectrum to raw CT-images. The applicability and performance of the techniques are showcased by describing extraction of 3D pore structures from micro-CT images of porous basalt using artifacts reductions, binarization, and volume stacking. Comparisions between calibrated and raw images indicate that the artifacts removal allows us to avoid the overestimation of porosity of imaged materials, and proper calibration of the artifacts plays a crucial role in using X-ray CT for geomaterials.

키워드

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피인용 문헌

  1. Estimation the Porosity of Pervious Concretes based on X-Ray CT and Submerged Weight vol.13, pp.4, 2013, https://doi.org/10.9798/KOSHAM.2013.13.4.077
  2. X-ray CT 이미지를 이용한 암석의 특성 평가 방안 vol.29, pp.6, 2011, https://doi.org/10.7474/tus.2019.29.6.542