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Active Batch Sampling for Multi-Label Classification With Binary User Feedback
Multi-label classification is a generalization of multi-class classification, where a single data sample can have multiple labels. While deep neural networks have depicted commendable performance for multi-label learning, they require a large amount of manually annotated training data to attain good generalization capability. However, annotating a multi-label data sample requires a human oracle to consider the presence/absence of every single class individually, which is extremely laborious. Active learning algorithms automatically identify the salient and exemplar instances from large amounts of unlabeled data and are effective in reducing human annotation effort in inducing a machine learning model. In this paper, we propose a novel active learning framework for multi-label learning, which queries a batch of (image-label) pairs and for each pair, poses the question whether the queried label is present in the corresponding image; the human annotators merely need to provide a binary feedback (yes / no) in response to each query, which involves much less manual work. We pose the image and label selection as a constrained optimization problem and derive a linear programming relaxation to select a batch of (image-label) pairs, which are maximally informative to the underlying deep neural network. Our extensive empirical studies on three challenging datasets corroborate the potential of our method for real-world multi-label classification applications.