A hybrid CNN–ViT framework for skin disease classification via feature extraction and selection
摘要
Automated classification of skin diseases using deep learning and machine learning is becoming increasingly prominent in the field of medical imaging. This study explores a hybrid framework that combines convolutional neural networks (CNNs), vision transformers (ViTs), and traditional machine learning classifiers to distinguish between three common skin conditions: Psoriasis, Eczema, and Tinea Ringworm. A curated dataset of 2,750 clinical images sourced from DermNet and the Atlas of Dermatology was used, with two dataset splits: 70:15:15 and 80:10:10 for training, validation, and testing, respectively. Feature extraction was performed using five deep learning backbones—EfficientNet-B0, ResNet50, ConvNeXt-Tiny, Swin-Tiny, and DeiT-Small. To reduce dimensionality and enhance relevance, five feature selection techniques were applied: Boruta, Chi-Square, ANOVA, recursive feature elimination (RFE), and Kruskal–Wallis (KW). The selected features were then used to train five classical machine learning classifiers: support vector machine (SVM), logistic regression (LR), k-nearest neighbors (KNN), random forest (RF), and multilayer perceptron (MLP). All experiments were repeated with three random seeds (42, 99, and 123) to ensure robustness. Among the combinations, ConvNeXt-Tiny features selected via Boruta and classified using SVM delivered the best hybrid result, achieving an accuracy of 79.78%, a notable improvement over the baseline of 74.7% ± 0.0% on the 80:10:10 split. Additionally, an end-to-end classification approach was evaluated using four backbone models—ResNet50, EfficientNet-B0, ConvNeXt-Tiny, and Swin-Tiny—also across three runs with seeds 42, 99, and 123. Among these, the Swin-Tiny model achieved the highest performance, with an accuracy of 82.1% ± 1.3%. These findings demonstrate the strength of hybrid approaches that leverage both deep learning for feature extraction and classical machine learning for classification, alongside the competitive edge of end-to-end deep learning, particularly in dermatological image analysis.