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arXiv 1807.02137math.NAcs.NA
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基于混合平滑器的多网格算法用于变分和选择性分割模型

Multigrid Algorithm Based on Hybrid Smoothers for Variational and Selective Segmentation Models

The University of Liverpool(利物浦大学);Liverpool Heart and Chest Hospital(利物浦心脏和胸部医院)

Michael Roberts, Ke Chen, Klaus L. Irion

AI总结:

本文提出一种基于新非标准平滑器的多网格算法,用于解决变分分割模型中的非光滑系数问题,改进了传统线性平滑器的效率,通过局部傅里叶分析验证了算法的收敛性。

摘要:

图像自动分割以识别所有有意义部分是许多应用领域中最具挑战性和有用的任务之一。选择性分割旨在利用有限的用户指定信息提取一个或多个有趣的对象(而不是所有对象)。构建快速求解器仍然是两种模型类别的挑战。然而,我们的主要关注点是选择性分割。在本文中,我们开发了一种有效的多网格算法,基于新的非标准平滑器来处理非光滑系数,以解决一类变分分割模型在水平集公式中的底层偏微分方程(PDEs)。对于此类模型,非光滑性(或跳跃)是典型的,因为只有在存在边缘(跳跃)的情况下才能进行分割。与之前多网格方法相比,这些方法被证明能够产生可接受的平均平滑率,而新算法可以确保小的全局平滑率,这是收敛的充分条件。我们的速率分析通过局部傅里叶分析进行,并借此设计了相应的迭代求解器,改进了无效的线性平滑器。数值测试表明,新算法在基于竞争平滑器的多网格方法中表现更优。

英文摘要:

Automatic segmentation of an image to identify all meaningful parts is one of the most challenging as well as useful tasks in a number of application areas. This is widely studied. Selective segmentation, less studied, aims to use limited user specified information to extract one or more interesting objects (instead of all objects). Constructing a fast solver remains a challenge for both classes of model. However our primary concern is on selective segmentation. In this work, we develop an effective multigrid algorithm, based on a new non-standard smoother to deal with non-smooth coefficients, to solve the underlying partial differential equations (PDEs) of a class of variational segmentation models in the level set formulation. For such models, non-smoothness (or jumps) is typical as segmentation is only possible if edges (jumps) are present. In comparison with previous multigrid methods which were shown to produce an acceptable {\it mean} smoothing rate for related models, the new algorithm can ensure a small and {\it global} smoothing rate that is a sufficient condition for convergence. Our rate analysis is by Local Fourier Analysis and, with it, we design the corresponding iterative solver, improving on an ineffective line smoother. Numerical tests show that the new algorithm outperforms multigrid methods based on competing smoothers.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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