提出双阶段方法检测隐形眼镜,提升虹膜识别准确性。
Detecting Clear Contact Lenses for Iris Recognition: A Two-Stage Mask-Guided Attention Approach

- 分两阶段检测:先用现成模型识图案镜片,再用注意力机制辨透明镜片。
- 在四个数据集上准确率达90.0%至98.8%,显著降低误识率。
- 适合关注生物特征安全与虹膜识别鲁棒性的研究人员。
本文研究透明处方隐形眼镜对虹膜识别的影响与检测问题。尽管彩色或花纹镜片已在演示攻击检测(PAD)框架下被广泛研究,但普遍使用的透明镜片因无明显纹理特征,常被忽视。我们通过商业VeriEye匹配器在四个基准数据集上验证,发现透明镜片虽轻微降低真匹配分数,却增加验证错误。为此提出双阶段检测框架:第一阶段使用现有PAD模型识别花纹镜片;第二阶段采用配备掩码引导空间注意力(MGSA)的ConvNeXt-Base模型,结合霍夫提取的解剖学感兴趣区域掩码与通道重校准机制,聚焦于角膜缘细微线索。该方法在四组数据集上整体准确率达90.0%–98.8%。此外,引入基于z-score的匹配分数校准方法,当检测到透明镜片时调整输出,使误识率(EER)下降4.1%–28.3%,证明可靠检测可直接提升虹膜验证性能。
原文摘要 · Abstract (English)
This work focuses on the impact and detection of clear contact lenses in the context of iris recognition. While the detection of cosmetic or patterned contact lenses has been extensively studied under the presentation attack detection (PAD) paradigm, clear prescription contact lenses, that are typically transparent, have received comparatively less attention despite their widespread use. Unlike patterned lenses, clear lenses introduce no salient texture artifact, making them difficult to detect and are often assumed to have no impact on iris recognition. We first examine this assumption using the commercial VeriEye matcher on four benchmark datasets and show that clear lenses marginally degrade genuine match scores and increase verification error. We then propose a two-stage contact-lens detection framework. Stage~1 uses an existing PAD model to identify patterned lenses, while Stage~2 focuses on the more challenging clear-lens versus no-lens distinction using a ConvNeXt-Base model equipped with Mask-Guided Spatial Attention (MGSA). The proposed MGSA module incorporates a Hough-derived anatomical ROI mask together with learned spatial attention and Squeeze-and-Excitation channel recalibration, allowing the network to focus on subtle limbal cues associated with clear lens wear. Across four datasets, the full pipeline consisting of both patterned and clear contact lens detection achieves between 90.0\%--98.8\% accuracy. Finally, we introduce a z-score calibration method that adjusts VeriEye match scores when a clear lens is detected in the input images. This calibration reduces EER by 4.1\%--28.3\% across datasets, demonstrating that reliable clear contact lens detection can directly improve iris verification performance.
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