TSM-Transformer: a hybrid EfficientNetV2-Lite and temporal shift model for facial expression recognition in videos
摘要
Many important applications rely on Dynamic Facial Expression Recognition (DFER), including affective computing, mental health monitoring, and human–computer interaction. The computational cost of current state-of-the-art approaches is increased and important contextual clues are lost due to their reliance on Face Detection and Alignment (FDA) preprocessing. This paper proposes a novel FDA-free hybrid DFER framework TSM-Transformer that integrates EfficientNetV2-Lite for lightweight spatial feature extraction, Temporal Shift Modules (TSM) for parameter-free local motion encoding, and a Transformer-based temporal fusion mechanism for global sequence modeling. By processing full-frame video inputs, the proposed model preserves both facial and body cues, enhancing robustness under real-world conditions with variations in lighting, occlusions, head poses, and background complexity. Experimental evaluation on a multi-class emotion dataset demonstrates that the TSM-Transformer achieves state-of-the-art performance, with 91.38% accuracy, 0.895 F1-score, and consistently high AUC values (0.92–0.97) across seven emotion categories. Notably, the model records significant gains in challenging classes such as Surprise (+ 5%) and Fear (+ 8%) over strong baselines, while maintaining real-time inference capability without computationally expensive preprocessing. Ablation studies confirm the complementary strengths of TSM and Transformer modules in capturing both micro- and macro-expression dynamics. The proposed approach offers a scalable, deployment-ready solution for DFER in unconstrained environments, with potential for extension to multimodal emotion recognition.