• The KIPS Transactions:PartA
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• v.14A no.2
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• pp.77-84
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• 2007

The intima media thickness(IMT) of the carotid artery from B mode ultrasound images has recently been proposed as the most useful index of individual atherosclerosis and can be used to predict major cardiovascular events. Ultrasonic measurements of the IMT are conventionally obtained by manually tracing interfaces between tissue layers. The drawbacks of this method are the inter and intra observer variability and its inefficiency. In this paper, we present a multiresolution snake method combined with the dynamic programming, which overcomes the various noises and sensitivity to initialization of conventional snake. First, an image pyramid is constructed using the Gaussian pyramid that maintains global edge information with smoothing in the images, and then the boundaries are automatically detected in the lowest resolution level by minimizing a cost function based on dynamic programming. The cost function includes cost terms which are representing image features and geometrical continuity of the vessel interfaces. Since the detected boundaries are selected as initial contour of the snake for the next level, this automated approach solves the problem of the initialization. Moreover, the proposed snake improves the problem of converging th the local minima by defining the external energy based on multiple image features. In this paper, our method has been validated by computing the correlation between manual and automatic measurements. This automated detection method has obtained more accurate and reproducible results than conventional edge detection by considering multiple image features.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.11a
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• pp.385-386
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• 2009

활성 윤곽선 모델은 스네이크 모델이라고도 하며 영상에서 물체의 경계를 검출하기위한 효과적인 방법으로 사용되고 있다. 본 논문에서는 초기 윤곽선 문제와 효과적인 경계선 검출을 위해 다해상도 기반의 유전자 알고리즘을 이용한 활성 윤곽선 모델을 제안한다. 입력영상의 해상도를 영상 피마리드 기법으로 저해상도로 축소시키고 초기 윤곽선을 설정한다. 설정된 윤곽선상의 연속된 두 좌표를 유전인자로 선택하고, 유전 연산자를 적용하여 물체의 경계를 찾아간다. 경계가 검출된 저해상도 영상을 단계적으로 확대하여, 보간될 영역의 국부적 활성 윤곽선 에너지를 계산하여 최소 에너지를 갖는 위치에 새로운 윤곽선 좌표를 삽입하여 경계를 형성한다. 제안된 방법은 초기 윤곽선의 위치에 상관없이 경계선을 검출했으며, 형태가 복잡한 물체의 경우에도 효과적으로 경계선을 검출하고 계산 복잡도를 감소시켰다.