A Collaborative Learning-based Urban Low-light Small-target Face Image Enhancement Method

Face recognition is an essential technology in intelligent transportation and security within smart cities. Nevertheless, face images taken in nighttime urban environments often suffer from low brightness, small sizes, and low resolution, which pose significant challenges for accurate face feature recognition. To address this issue, we propose the Low-light Small-target Face Enhancement (LSFE) method, a collaborative learning-based image brightness enhancement approach specifically designed for small-target faces in low-light environments. LSFE employs a multilevel feature stratification module to acquire detailed face image features at different levels, revealing hidden facial image information within the dark. In addition, we design a network combining collaborative learning and self-attention mechanisms, which effectively captures long-distance pixel dependencies in low-brightness face images and enhances their brightness in a stepwise manner. The enhanced feature maps are then fused through a branch fusion module. Experimental results demonstrate that LSFE can more effectively enhance the luminance of small-target face images in low-light scenes while retaining more visual information, compared to other existing methods.