Enhancing skin lesion classification using a Tri-Path Attention Stacked Ensemble architecture with Cohen's Kappa...

Early recognition of skin lesions, including diverse abnormalities and life-threatening skin cancers, is critical for effective treatment and improved clinical outcomes. However, existing skin lesion datasets exhibit significant class imbalance, and there is no standardized guideline for optimal data augmentation strategies. This study aims to establish a robust and interpretable framework that addresses these limitations while enhancing diagnostic performance.

We propose a novel transfer learning-based framework termed Tri-Path Attention Stacked Ensemble (TASE), which integrates multiple EfficientNetV2 backbones through three distinct stacking strategies: TASE: Independent TA, TASE: Serial Stacked TA, and TASE: Parallel Stacked TA. Here, TA refers to the Triple-Attention mechanism, comprising soft attention integration, channel attention integration, and squeeze-excitation attention integration. To optimize ensemble prediction fusion, we introduce an advanced aggregation method-Cohen's Kappa Proportioned Averaging (CKPA)-which is further extended into a Multi-Layer CKPA (ML-CKPA) framework to enhance weight distribution across hierarchical model outputs. Additionally, four augmentation strategies were systematically evaluated to determine the most effective ensemble configuration.

Experimental validation on the HAM10000 dataset demonstrated that the proposed framework achieved a superior accuracy of 94.44%, outperforming several state-of-the-art methods. Grad-CAM visualizations were employed to enhance interpretability by highlighting lesion-relevant regions, thereby improving model transparency and reliability.

The proposed TASE framework delivers enhanced diagnostic accuracy while effectively mitigating challenges related to class imbalance, dataset variability, and computational efficiency. By combining hierarchical triple-attention mechanisms with multi-layer ensemble weighting, it offers a reliable and interpretable solution for early and precise skin lesion classification, supporting real-world dermatological applications and improved patient care.