Video Object Matting via Hierarchical Space-Time Semantic Guidance

Yumeng Wang, Bo Xu, Ziwen Li, Han Huang, Cheng Lu, Yandong Guo; Proceedings of the IEEE/CVF Winter Conference on Applications of Computer Vision (WACV), 2023, pp. 5120-5129

Different from most existing approaches that require trimap generation for each frame, we reformulate video object matting (VOM) by introducing improved semantic guidance propagation. The proposed approach can achieve a higher degree of temporal coherence between frames with only a single coarse mask as reference. In this paper, we adapt the hierarchical memory matching mechanism into the space-time baseline to build an efficient and robust framework for semantic guidance propagation and alpha prediction. To enhance the temporal smoothness, we also propose a cross-frame attention refinement (CFAR) module that can refine the feature representations across multiple adjacent frames (both historical and current frames) based on the spatio-temporal correlation among the cross-frame pixels. Extensive experiments demonstrate the effectiveness of hierarchical spatio-temporal semantic guidance and the cross-video-frame attention refinement module, and our model outperforms the state-of-the-art VOM methods. We also analyze the significance of different components in our model.