arXiv:2607.22872cs.LGcs.CV2026-07

量化压缩会改变模型解释,不同架构表现差异大。

Same Predictions, Different Reasons: The Effect of Quantization on Model Explanations

论文配图:Same Predictions, Different Reasons: The Effect of Quantization on Model Explanations
图 1 · 摘自论文原文
  • 用梯度热力图与局部重要性分析对比精度压缩前后解释变化
  • INT8/INT4下准确率不变,但解释一致性显著下降
  • 适合对可解释性要求高的场景,如医疗、自动驾驶

后训练量化(PTQ)通过将高精度浮点权重压缩为低精度表示,成为在资源受限边缘设备部署深度学习模型的实用方案,无需重新训练。以往研究显示量化基本保持分类准确率;然而,其是否保留模型内部推理过程仍存疑问。本研究系统评估了静态PTQ对五种主流CNN架构(VGG19、ResNet18、EfficientNet-B0、DenseNet161、MobileNetV2)在INT8和INT4精度下的可解释性影响。采用结合Grad-CAM与LIME的双重解释框架,在两个二分类数据集上对比全精度与量化模型。通过皮尔逊相关系数、结构相似性指数及前20% IoU等三类指标,捕捉解释分布与结构变化,并辅以删除/插入忠实性分析。结果表明:分类准确率不能作为解释稳定性可靠指标。DenseNet161在两种精度下均保持强特征一致性;而EfficientNet-B0虽在INT8下空间注意力与准确率表现良好,但在输入级特征归因上出现显著退化。该发现对高可解释性要求应用中量化模型的可信部署具有直接影响,强调架构选择与量化策略同等重要。

原文摘要 · Abstract (English)

Post-training quantization (PTQ) has become a practical solution for deploying deep learning models on resource-constrained edge devices by compressing high-precision floating-point weights into low-precision representations without requiring retraining. Past research has demonstrated that quantization largely preserves classification accuracy; however, whether it also preserves the model's internal reasoning remains an open question. This study presents a systematic evaluation on how static PTQ affects the interpretability / explainability of five widely used CNN architectures: VGG19, ResNet18, EfficientNet-B0, DenseNet161, and MobileNetV2 at INT8 and INT4 precision. We employ a dual interpretability framework that combines Grad-CAM for spatial attention analysis with LIME for input-level feature attribution, and systematically compare full-precision and quantized models on two binary classification datasets. Interpretability is evaluated using three complementary metrics: the Pearson correlation coefficient, structural similarity index, and top-20% IoU to capture distributional and structural variations in model explanations, supplemented by deletion/insertion faithfulness analysis. The results show that classification accuracy is not a reliable indicator of interpretability stability under reduced precision. DenseNet161 maintains strong feature consistency across both precision levels, whereas EfficientNet-B0, despite achieving competitive spatial attention and classification accuracy at INT8 precision, exhibits a substantial degradation in input-level feature attribution. These findings have direct implications for the trustworthy deployment of quantized models in applications with high interpretability requirements, demonstrating that architecture selection is as important as the quantization strategy.

模型量化可解释性CNN解释一致性

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