Bottom Up and Top Down Attention for Image Captioning and Visual Question Answering
Top down visual attention mechanisms have been used extensively in image captioning and visual question answering (VQA) to enable deeper image understanding through fine grained analysis and even multiple steps of reasoning. In this work, we propose a combined bottom up and top down attention mechanism that enables attention to be calculated at the level of objects and other salient image regions. This is the natural basis for attention to be considered. Within our approach, the bottom up mechanism (based on Faster R CNN) proposes image regions, each with an associated feature vector, while the top down mechanism determines feature weightings. Applying this approach to image captioning, our results on the MSCOCO test server establish a new state of the art for the task, achieving CIDEr SPICE BLEU 4 scores of 117.9, 21.5 and 36.9, respectively. Demonstrating the broad applicability of the method, applying the same approach to VQA we obtain first place in the 2017 VQA Challenge.
2018 IEEE/CVF Conference on Computer Vision and Pattern Recognition