Lightweight Visual Question Answering using Scene Graphs
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Visual question answering (VQA) is a challenging problem in machine perception, which requires the deep joint understanding of both visual and textual data. Recent research has advanced the automatic generation of high-quality scene graphs from images, while powerful yet elegant models like graph neural networks (GNNs) have shown a great power in reasoning over graph-structured data. In this work, we propose to bridge the gap between scene graph generation and VQA by leveraging GNNs. In particular, we design a new model called Conditional Enhanced Graph ATtention network (CE-GAT) to encode pairs of visual and semantic scene graphs with both node and edge features, which is seamlessly integrated with a textual question encoder to generate answers through questiongraph conditioning. Moreover, to alleviate the training difficulties of CE-GAT towards VQA, we enforce more useful inductive biases in the scene graphs through novel question-guided graph enriching and pruning. Finally, we evaluate the framework on one of the largest available VQA datasets (namely, GQA) with groundtruth scene graphs, achieving the accuracy of 77.87%, compared with the state of the art (namely, the neural state machine (NSM)), which gives 63.17%. Notably, by leveraging existing scene graphs, our framework is much lighter compared with end-to-end VQA methods (e.g., about 95.3% less parameters than a typical NSM).
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