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Iris biometric systems offer non-contact authentication, particularly advantageous in controlled environments such as security checkpoints. However, challenges arise in less controlled scenarios such as standoff biometrics where captured images mostly are non-ideal including off-angle. This paper addresses the need for iris recognition models adaptable to various gaze angles by proposing a blink detection algorithm as an additional feature. The study explores different blink detection methods including involving logistic regression, random forest, and deep learning models. For the first methodology, logistic regression and a random forest model were used to classify eye images into four different blink classes. The second methodology involved labeling eye openness percentage. The ground-truth eye blink was calculated using facial landmarks detected by the MediaPipe model. For the deep learning approach, we used a pre-trained Convolutional Neural Network (CNN) model by replacing the output layer with a regression layer. Results show improved precision and recall when incorporating height and width features for the regression model. The AlexNet model achieves superior performance, reaching 90% accuracy with a 10 % error threshold. This research contributes valuable insights for developing robust iris recognition models adaptable to diverse gaze angles. 

Iris recognition is a widely used biometric technology that has high accuracy and reliability in well-controlled environments. However, the recognition accuracy can significantly degrade in non-ideal scenarios, such as off-angle iris images. To address these challenges, deep learning frameworks have been proposed to identify subjects through their off-angle iris images. Traditional CNN-based iris recognition systems train a single deep network using multiple off-angle iris image of the same subject to extract the gaze invariant features and test incoming off-angle images with this single network to classify it into same subject class. In another approach, multiple shallow networks are trained for each gaze angle that will be the experts for specific gaze angles. When testing an off-angle iris image, we first estimate the gaze angle and feed the probe image to its corresponding network for recognition. In this paper, we present an analysis of the performance of both single and multimodal deep learning frameworks to identify subjects through their off-angle iris images. Specifically, we compare the performance of a single AlexNet with multiple SqueezeNet models. SqueezeNet is a variation of the AlexNet that uses 50x fewer parameters and is optimized for devices with limited computational resources. Multi-model approach using multiple shallow networks, where each network is an expert for a specific gaze angle. Our experiments are conducted on an off-angle iris dataset consisting of 100 subjects captured at 10-degree intervals between -50 to +50 degrees. The results indicate that angles that are more distant from the trained angles have lower model accuracy than the angles that are closer to the trained gaze angle. Our findings suggest that the use of SqueezeNet, which requires fewer parameters than AlexNet, can enable iris recognition on devices with limited computational resources while maintaining accuracy. Overall, the results of this study can contribute to the development of more robust iris recognition systems that can perform well in non-ideal scenarios.