Memory-Efficient Incremental Learning Through Feature Adaptation
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In this work we introduce an approach for incremental learning, which preserves feature descriptors instead of images unlike most existing work. Keeping such low-dimensional embeddings instead of images reduces the memory footprint significantly. We assume that the model is updated incrementally for new classes as new data becomes available sequentially. This requires adapting the previously stored feature vectors to the updated feature space without having access to the corresponding images. Feature adaptation is learned with a multi-layer perceptron, which is trained on feature pairs of an image corresponding to the outputs of the original and updated network. We validate experimentally that such a transformation generalizes well to the features of the previous set of classes, and maps features to a discriminative subspace in the feature space. As a result, the classifier is optimized jointly over new and old classes without requiring old class images. Experimental results show that our method achieves state-of-the-art classification accuracy in incremental learning benchmarks, while having at least an order of magnitude lower memory footprint compared to image preserving strategies.
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