Direction Relation Transformer for Image Captioning

Image captioning is a challenging task that combines computer vision and natural language processing for generating a textual description of the content within an image. Recently, Transformer-based encoder-decoder architectures have shown great success in image captioning, where multi-head attention mechanism is utilized to capture the contextual interactions between object regions. However, such methods regard region features as a bag of tokens without considering the directional relationships between them, making it hard to understand the relative position between objects in the image and generate correct captions effectively. In this paper, we propose a novel Direction Relation Transformer to improve the orientation perception between visual features by incorporating the relative direction embedding into multi-head attention, termed DRT. We first generate the relative direction matrix according to the positional information of the object regions, and then explore three forms of direction-aware multi-head attention to integrate the direction embedding into Transformer architecture. We conduct experiments on challenging Microsoft COCO image captioning benchmark. The quantitative and qualitative results demonstrate that, by integrating the relative directional relation, our proposed approach achieves significant improvements over all evaluation metrics compared with baseline model, e.g., DRT improves task-specific metric CIDEr score from 129.7% to 133.2% on the offline ''Karpathy'' test split.