Application of Semi-Supervised Learning in Image Classification: Research on Fusion of Labeled and Unlabeled Data

Deep learning has attracted wide attention recently because of its excellent feature representation ability and end-to-end automatic learning method. Especially in clinical medical imaging diagnosis, the semi-supervised deep learning model is favored and widely used because it can make maximum use of a limited number of labeled data and combine it with a large number of unlabeled data to extract more information and knowledge from it. However, the scarcity of medical image data, the vast image size, and the instability of image quality directly affect the model’s robustness, generalization, and image classification performance. Therefore, this paper proposes a new semi-supervised learning model, which uses quadratic neurons instead of traditional neurons, aiming to use quadratic convolution instead of the conventional convolution layer to improve the feature extraction ability of the model. In addition, we introduce two Dropout layers and two fully connected layers at the end of the model to enhance the nonlinear fitting ability of the network. Experiments on two large medical public data sets - ISIC 2019 and Retinopathy OCT - show that our method can improve the model’s generalization performance and image classification accuracy.