DIANet: A Phase-Aware Dual-Stream Network for Micro-Expression Recognition via Dynamic Images
This work addresses a domain-specific problem in psychology, security, and behavioral analysis by improving recognition of subtle facial expressions, though it is incremental as it builds on existing dynamic image methods.
The paper tackled the challenge of micro-expression recognition by proposing DIANet, a dual-stream network that uses phase-aware dynamic images to model distinct temporal phases, and it outperformed conventional single-phase methods on three benchmark datasets.
Micro-expressions are brief, involuntary facial movements that typically last less than half a second and often reveal genuine emotions. Accurately recognizing these subtle expressions is critical for applications in psychology, security, and behavioral analysis. However, micro-expression recognition (MER) remains a challenging task due to the subtle and transient nature of facial cues and the limited availability of annotated data. While dynamic image (DI) representations have been introduced to summarize temporal motion into a single frame, conventional DI-based methods often overlook the distinct characteristics of different temporal phases within a micro-expression. To address this issue, this paper proposes a novel dual-stream framework, DIANet, which leverages phase-aware dynamic images - one encoding the onset-to-apex phase and the other capturing the apex-to-offset phase. Each stream is processed by a dedicated convolutional neural network, and a cross-attention fusion module is employed to adaptively integrate features from both streams based on their contextual relevance. Extensive experiments conducted on three benchmark MER datasets (CASME-II, SAMM, and MMEW) demonstrate that the proposed method consistently outperforms conventional single-phase DI-based approaches. The results highlight the importance of modeling temporal phase information explicitly and suggest a promising direction for advancing MER.