“…Moreover, feature extraction and selection methods are performed manually, which, in turn, can result in low performance if those features are not carefully picked out and, consequently, will not be very representative. Existing approaches that use deep CNN for palm vein verification and identification, including [27] [28] [29] [30], are very few and they employ fixed structures and training options for their CNN models. Moreover, studies that employ convolutional neural networks for similar applications with Bayesian optimization, such as [31] [32], use fixed structures or pretrained CNN models, and consider optimizing only the training options, such as learning rate and momentum, while ignoring the possibility of optimizing the network structure, such as the number of convolutional layers.…”