IMC-Det: Intra–Inter Modality Contrastive Learning for Video Object Detection

Video object detection is an important yet challenging task in the computer vision field. One limitation of off-the-shelf video object detection methods is that they only explore information from the visual modality, without considering the semantic knowledge of the textual modality due to the large inter-modality discrepancies, resulting in limited detection performance. In this paper, we propose a novel intra–inter modality contrastive learning network for high-performance video object detection (IMC-Det), which includes three substantial improvements over existing methods. First, we design an intra-modality contrastive learning module to pull close similar features while pushing apart dissimilar ones, enabling our IMC-Det to learn more discriminative feature representations. Second, we develop a graph relational feature aggregation module to effectively model the structural relations between features by leveraging cross-graph learning and residual graph convolution, which is conducive to performing more effective feature aggregation in the spatio-temporal domain. Third, we present an inter-modality contrastive learning module to enforce the visual features belonging to same classes to be compactly gathered around the corresponding textual semantic representations, endowing our IMC-Det with better object classification capability. We conduct extensive experiments on the challenging ImageNet VID dataset, and the experimental results demonstrate that our IMC-Det performs favorably against existing state-of-the-art methods. More remarkably, our IMC-Det achieves 85.5% mAP and 86.7% mAP with ResNet-101 and ResNeXt-101, respectively.