Beyond Categorical Label Representations for Image Classification

Boyuan Chen, Yu Li, Sunand Raghupathi, Hod Lipson

Keywords: Label Representation, Image Classification, Representation Learning

Abstract: We find that the way we choose to represent data labels can have a profound effect on the quality of trained models. For example, training an image classifier to regress audio labels rather than traditional categorical probabilities produces a more reliable classification. This result is surprising, considering that audio labels are more complex than simpler numerical probabilities or text. We hypothesize that high dimensional, high entropy label representations are generally more useful because they provide a stronger error signal. We support this hypothesis with evidence from various label representations including constant matrices, spectrograms, shuffled spectrograms, Gaussian mixtures, and uniform random matrices of various dimensionalities. Our experiments reveal that high dimensional, high entropy labels achieve comparable accuracy to text (categorical) labels on standard image classification tasks, but features learned through our label representations exhibit more robustness under various adversarial attacks and better effectiveness with a limited amount of training data. These results suggest that label representation may play a more important role than previously thought.

Code Of Ethics: I acknowledge that I and all co-authors of this work have read and commit to adhering to the ICLR Code of Ethics

One-sentence Summary: We study the role of label representations for standard image classification task and found high-dimensional hign-entropy labes generally lead to more robust and data-efficient networks.

Code: [ BoyuanChen/label_representations](https://github.com/BoyuanChen/label_representations)

Data: [CIFAR-10](https://paperswithcode.com/dataset/cifar-10), [CIFAR-100](https://paperswithcode.com/dataset/cifar-100)

Community Implementations: [ 1 code implementation](https://www.catalyzex.com/paper/arxiv:2104.02226/code)