针对传统参数活动轮廓模型存在对轮廓线初始位置敏感的缺点,提出了方向气球力活动轮廓模型并应用于MRI 图像分割。该模型利用底层图像分割的结果确定外力的方向,使气球力方向始终指向目标边界,引导轮廓线变形。当轮廓线运动到目标边界附近时,在高斯势力作用下继续变形,完成图像高层分割。实验结果表明,该模型与轮廓线初始位置无关,能实现MRI 图像的自动分割。 关键词: 图像分割; 方向气球力; 活动轮廓模型; 高斯势力 Abstract: Traditional parametric active contour model is sensitive to the initial position. An improved external force for the active contour, called directional balloon force is proposed to address problem associated with initialization and is used to segment MRI images. In this model the direction of the force is decided by the results of low-level segmentation and always points to object boundary to make the contour deform. In the vicinity of object boundary, Gaussian potential force drives the contour towards boundary and high-level segmentation is implemented. The experiments of segmenting left ventricle MRI images show that this model be independent of the initial position and can segment image automatically. Key words: image segmentation; directional balloon force; active contour model; Gaussian potential force