The Research of Using Snake Model to Extract Contours of Objects in Color Images
应用Snake模型提取彩色图象目标轮廓线的研究

In order to improve the effectiveness of Snake active model, the deformable template approach of contour-tracking algorithm, in color images, this paper mainly focuses on resolving two problems. First, to reduce the difficulty of handcrafting initial contour for Snake, the authors introduce the pretreatment procedure. They first use color-based clustering algorithm to divide an image into several regions, then use improved graph-searching algorithm to get the contour of independent regions which may be important for further recognition, and take this result as the initial contour. Second, to avoid the distortion contour produced by Snake model when applying it to tracking the contour in some color images, they redesign the external energy function of Snake. They use neighborhood pixels' Euclidean distance of the colors in weighted HSI color space, instead of grey level difference in traditional algorithms, to approximate the grads of image, and take the square of the distance as external energy function to keep the active contour staying at the place where the real contour locates. At last, comparing prototype of Snake model with the new method, authors illustrate that the improvement is considerable, especially when color images are involved.