提出一种基于拓扑的二值分割评估方法,能判断分割结果是否保持物体连通性。
Jordan-Segmentable Masks: A Topology-Aware definition for characterizing Binary Image Segmentation
- 基于乔丹曲线定理定义可分段掩码,通过数字拓扑判断分割结构是否合理
- 当掩码补集恰好分为两个8-连通区域时,判定为拓扑有效,符合β₀=β₁=1条件
- 适用于医学图像等需保证对象整体形状和连接性的场景
图像分割在计算机视觉中至关重要。然而,现有的评价指标(无论像素级、区域级还是边界聚焦)往往难以捕捉分割结果的结构与拓扑一致性。在医疗影像或目标轮廓分割等实际场景中,边界微小误差、孔洞或碎片化预测可能导致高评分,但分割结果未能保持对象的整体形状或连通性。这暴露了传统指标的局限:无法判断预测分割是否将图像域划分为有意义的内部与外部区域。本文引入一种基于乔丹曲线定理的拓扑感知分割概念,适用于数字平面。定义了「可分段乔丹掩码」,即其结构能确保图像域被拓扑分离为两个连通部分。通过数字拓扑与同调理论分析分割掩码,提取一个4-曲线候选,利用贝蒂数验证其拓扑有效性。当该候选构成数字4-曲线且满足β₀ = β₁ = 1,或等价地,其补集恰好分为两个8-连通区域时,认为掩码为乔丹可分段。该框架提供了一种数学严谨、无需监督的结构一致性评估标准。结合数字乔丹理论与同调不变量,为需保持拓扑正确性的应用场景提供了优于标准指标的替代方案。
原文摘要 · Abstract (English)
Image segmentation plays a central role in computer vision. However, widely used evaluation metrics, whether pixel-wise, region-based, or boundary-focused, often struggle to capture the structural and topological coherence of a segmentation. In many practical scenarios, such as medical imaging or object delineation, small inaccuracies in boundary, holes, or fragmented predictions can result in high metric scores, despite the fact that the resulting masks fail to preserve the object global shape or connectivity. This highlights a limitation of conventional metrics: they are unable to assess whether a predicted segmentation partitions the image into meaningful interior and exterior regions. In this work, we introduce a topology-aware notion of segmentation based on the Jordan Curve Theorem, and adapted for use in digital planes. We define the concept of a \emph{Jordan-segmentatable mask}, which is a binary segmentation whose structure ensures a topological separation of the image domain into two connected components. We analyze segmentation masks through the lens of digital topology and homology theory, extracting a $4$-curve candidate from the mask, verifying its topological validity using Betti numbers. A mask is considered Jordan-segmentatable when this candidate forms a digital 4-curve with $β_0 = β_1 = 1$, or equivalently when its complement splits into exactly two $8$-connected components. This framework provides a mathematically rigorous, unsupervised criterion with which to assess the structural coherence of segmentation masks. By combining digital Jordan theory and homological invariants, our approach provides a valuable alternative to standard evaluation metrics, especially in applications where topological correctness must be preserved.
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