针对图像中稀有位置重建模糊问题,提出双机制增强模型对罕见区域的关注。
Rare-Aware Autoencoding: Reconstructing Spatially Imbalanced Data
- 用自熵损失提升统计罕见空间位置的权重
- 通过样本重播机制反复训练难重构样本
- 适合医学、生物等稀疏数据场景下的图像重建
自编码器在图像内容空间分布不均时面临挑战,尤其在医学、生物和物理领域,关键模式常出现在少数特定位置,而背景占主导导致重建偏向常见外观。现有方法在未标注数据中表现不佳,尤其在空间不平衡下丢失细节并产生模糊结果。本文提出两种互补策略:(i) 基于自熵的损失函数,提升统计罕见空间位置的权重;(ii) 样本传播机制,在训练中选择性重复暴露模型于难重构样本。我们在模拟数据集及三个真实世界数据集(涵盖物理、生物、天文)上验证,覆盖受控与非受控空间不平衡场景。实验表明,该方法在多种重建指标上优于基线,尤其在严重不平衡条件下效果显著。结果强调了批内数据表示的重要性,并突出罕见样本在无监督图像重建中的价值。代码与数据将公开。
原文摘要 · Abstract (English)
Autoencoders can be challenged by spatially non-uniform sampling of image content. This is common in medical imaging, biology, and physics, where informative patterns occur rarely at specific image coordinates, as background dominates these locations in most samples, biasing reconstructions toward the majority appearance. In practice, autoencoders are biased toward dominant patterns resulting in the loss of fine-grained detail and causing blurred reconstructions for rare spatial inputs especially under spatial data imbalance. We address spatial imbalance by two complementary components: (i) self-entropy-based loss that upweights statistically uncommon spatial locations and (ii) Sample Propagation, a replay mechanism that selectively re-exposes the model to hard to reconstruct samples across batches during training. We benchmark existing data balancing strategies, originally developed for supervised classification, in the unsupervised reconstruction setting. Drawing on the limitations of these approaches, our method specifically targets spatial imbalance by encouraging models to focus on statistically rare locations, improving reconstruction consistency compared to existing baselines. We validate in a simulated dataset with controlled spatial imbalance conditions, and in three, uncontrolled, diverse real-world datasets spanning physical, biological, and astronomical domains. Our approach outperforms baselines on various reconstruction metrics, particularly under spatial imbalance distributions. These results highlight the importance of data representation in a batch and emphasize rare samples in unsupervised image reconstruction. We will make all code and related data available.
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