摘要： 图像因光照、结构复杂等因素在靠近轮廓内部时存在边界强度大的重边界,采用梯度矢量流(GVF)Snake模型提取此类图像的轮廓时,初始轮廓线会错误地收敛到重边界上,称作分心问题。从GVF场力变化的角度分析迭代次数、边界强度差对分心问题的影响,发现增强GVF边缘图弱边界的强度能使弱边界附近的场力不受重边界的影响。为此,利用经典Canny算法代替传统GVF边缘图的计算方法。针对经典Canny算法丢失弱边界的不足,提出一种改进的Canny算法,将梯度方向作为补偿权重增加梯度幅值。实验结果表明,改进的Canny算法能够较好地保留弱边界,以此算法作为GVF的边缘图可有效解决分心问题,并且相比利用减少迭代次数抑制分心问题的方法具有更好的稳定性。

关键词: 梯度矢量流Snake模型, 分心问题, 重边界, 改进Canny算法, 弱边界增强

Abstract: Due to the light,complex structure and other reasons,there are inevitable heavy boundary with large boundary intensity near the target contour.Using the Gradient Vector Flow(GVF) Snake model to extract the contour of the image,the initial contour wrongly converges to the heavy boundary,and this phenomenon is called distraction.From the perspective that the GVF field force changes,the influence of the number of iterations and the intensity difference on the distraction are analyzed in detail.It is found that the enhancing intensity of GVF edge map’s weak boundary makes the field force near the weak boundary free from the affect of the heavy boundary.To this end,the edge detected by the classical Canny algorithm is used to replace the traditional GVF edge map calculation method.To solve the problem of weak boundary loss of classical Canny algorithm,an improved Canny algorithm is proposed,and the gradient direction is used as the compensation weight to increase the gradient amplitude.Experimental results show that the improved Canny algorithm can preserve the weak boundary well,and the GVF edge map based on this algorithm can effectively solve the problem of distraction.Compared with the method of reducing the number of iterations,this method has better stability.

Key words: Gradient Vector Flow(GVF) Snake model, distraction problem, heavy boundary, improved Canny algorithm, weak boundary enhancement

中图分类号: 

• TP391.4