目的 虹膜识别是具有发展前景的生物特征认证方式,然而现有的一些方法无法在远距离、非协作状态下捕获的低质量图像中表现出较好的性能,极大阻碍了虹膜识别在实际中的应用部署。为此,提出一种基于卷积神经网络的网络模型,使用眼周和虹膜进行有效融合,克服单一模态生物特征的局限性,增强生物特征身份认证方式的可靠性和安全性。方法 为了能够提取鲁棒性更强的辨别特征,将空间注意力机制和特征重用方法进行结合,有效减轻了在前向传播过程中梯度消失的问题。同时,引入中间融合表达层,根据不同模态低、中、高层特征信息对融合策略产生的贡献值自适应地学习相对应的权重,并通过加权组合的方式有效地融合生成鲁棒性更强的辨别特征,极大提升了虹膜识别在远距离、非协作状态下的识别性能。结果 在3个公开数据集ND-IRIS-0405(notre dame)、CASIA (Institute of Automation,Chinese Academy of Sciences)-Iris-M1-S3以及CASIA-Iris-Distance上进行测试,本文方法EER (equal error rate)值分别为0.19%,0.48%,1.33%,优于对比方法,表明了本文方法的优越性。结论 本文提出的中间融合表达层融合方法能够有效融合眼周和虹膜在不同阶段的语义信息,生成判别性更强的特征模板,提升了远距离、非协作状态下虹膜识别的性能。
Iris-periocular features-fused non-collaborative authentication
Objective Identity authentication method is in relevance with the biological characteristics of the human body， which is benefited from breakthrough of computer technology and consistent improvement of hardware computing ability in the past 20 years. The biometrics-relevant artificial intelligence（AI）technology has been developed intensively. Irisrelated features analysis is crucial for biometric authentication method. Current iris recognition technique is used to optimize short-distance and specific scenarios，but it is still challenged for the applications in the context of long-distance and non-collaborative scenarios. There are two main constraints as mentioned below：first，the iris recognition process is required for a short distance-relevant sensor-based instruction in terms of matching-completed prompts. This acquisition process is challenged for large-scale application farther. Second，current sensor-based hardware acquisition is increased as the distance between target and acquisition device. The accuracy and reliability of recognition will be lower severely because the quality of iris image-gathered is not effective. The iris recognition performance is required to be improved for long-distance and low-quality images and non-prompted scenes. To get credible identity authentication，a variety of biometrics are focused on iris recognition-assisted. Multiple modal-fused biometric information is more effective compared to single modality based identification. First，due to the heterogeneity of biological characteristics，a variety of modes of biometric recognition needs to be mutual-benefited. Second，safe authentication methods will not be guaranteed effectively when the biometric information storage encounters information leakage. To meet the needs of iris recognition in real scenario，it is necessary to generate richer biometric information in the eye area of the human face，such as the iris and eye area. Eye area-related semantic information has good recognizability for identity identification，but the eye area recognition is disturbed easily by complex background information. The iris texture features are relatively stable and iris recognition is affected less. Therefore，to get accurate and stable authentication in non-prompted and long-distance scenarios，effective fusion of the eye circumference and iris can be optimized to achieve modalities-mutual benefits and enhance the reliability and security of biometric identity authentication. Method Some of the existing methods pay more attention on the highdimensional semantic feature layer. To fuse the feature vectors of different modes，addition，multiplication and other related ways are then used. Due to great limitations，lack of certain flexibility and adaptability，the differences and the semantic characteristics of each mode are ignored at different stages. It is ineffective to combine multimode information of different stages mutually. To extract more robusted and distinctive features，the spatial attention mechanism and featurereused method are coordinated and the model-opted can be focused on the feasible iris texture area，and the problem of gradient disappearance is alleviated via propagation-forward. For fusion strategy，the introduction of intermediate fusion expression layer can be adaptively used to learn the corresponding weights according to the contribution value of low， medium and high-level feature information of different modes，and it can be fused to generate more robust and distinctive features in terms of the integrated weights，which can improve the recognition performance of iris recognition in longdistance and non-cooperative status. Result To verify the effectiveness of the proposed method，experiments are carried out and compared to three popular public datasets，called notre dame（ND）-IRIS-0405，Institute of Automation， Chinese Academy of Sciences（CASIA）-Iris-M1-S3，and CASIA-Iris-Distance. Comparative analysis is in comparison with other related state-of-the-arts methods，including false reject rate（FRR），true accept rate（TAR），and equal error rate（EER）. Lower FRR and EER values can indicate better performance，while TAR is vice versa. The test results of the three publicly available datasets can demonstrate that each EER value can be optimized and reached to 0. 19%，0. 48% and 1. 33%. Conclusion We develop a convolutional neural network（CNN）based model. The model is focused on the iris texture area in terms of the integration of efficient channel attention mechanism and feature-reused and the problem of model gradient disappearance can be alleviated to a certain extent，which is beneficial for the depth of the model and robust distinctive features. At the same time，the intermediate fusion joint expression layer is introduced and focused on characteristics of semantic features of different modes at different stages，and it can learn the corresponding weights adaptively according to the degree of contribution generated by the low，medium and high semantic features of different modes，and the iris and eye area features are fused into distinctive features more through weighted fusion，which can improve the iris recognition performance in long-distance and non-cooperative status. This method is easy to be trainable as well.