GVF

代码说明：

  图象分割算法，这是 active contours分割中外力的选择，通常算法为基于梯度，但对于梯度不清楚的图像，可以采用此方法(image segmentation algorithm, which is active segmentation external contours of choice, usually based on the gradient algorithm, but the gradient was not clear images, we can use this method)