Applications of Neural Attention for Modelling Long-Range Dependencies

Abstract

Dominant neural network architectures such as Convolutional Neural Networks (CNNs) and Recurrent Neural Networks (RNNs) are inherently local and require deep networks to incorporate distant information. Early work on visual attention al- lowed the modelling of non-local structures through sequences of local glimpses, and more recently, the Transformer family of networks revolutionised neural attention by using self-attention to process all inputs in parallel. This thesis explores applications of neural attention mechanisms in computer vision, focusing on modelling long-range dependencies in three domains: historical document analysis, biomedical data processing, and stereo-image compression. Moreover, it introduces new methods that use attention mechanisms to address specific challenges in these domains. A visual attention-based method for extracting text baselines from images of historical handwritten texts is presented. The proposed method relies on a network that sequentially shifts attention along text lines to determine polygon coordinates. The method allows for direct learned prediction of text baseline coordinates rather than relying on heuristics. In the biomedical domain, the thesis introduces the Flowformer model, an efficient variant of the Transformer architecture designed to process large flow cytometry samples for cancer cell detection. The proposed approach uses global attention to model samples holistically and achieves state-of- the-art performance in cancer cell identification across multiple datasets. Finally, two stereo image compression models, SASIC and ECSIC, are presented, which use cross-attention mechanisms to model the mutual information between stereo image pairs. These methods achieve state-of-the-art compression performance by efficiently capturing redundancies between images while maintaining fast runtimes. This thesis provides explicit solutions to real-world problems in document analysis, biomedical data processing, and image compression. It also demonstrates the effectiveness of neural attention in dealing with different long-range dependencies.