  Long-tailed learning has attracted much attention recently, with the goal of
improving generalisation for tail classes. Most existing works use supervised
learning without considering the prevailing noise in the training dataset. To
move long-tailed learning towards more realistic scenarios, this work
investigates the label noise problem under long-tailed label distribution. We
first observe the negative impact of noisy labels on the performance of
existing methods, revealing the intrinsic challenges of this problem. As the
most commonly used approach to cope with noisy labels in previous literature,
we then find that the small-loss trick fails under long-tailed label
distribution. The reason is that deep neural networks cannot distinguish
correctly-labeled and mislabeled examples on tail classes. To overcome this
limitation, we establish a new prototypical noise detection method by designing
a distance-based metric that is resistant to label noise. Based on the above
findings, we propose a robust framework,~\algo, that realizes noise detection
for long-tailed learning, followed by soft pseudo-labeling via both label
smoothing and diverse label guessing. Moreover, our framework can naturally
leverage semi-supervised learning algorithms to further improve the
generalisation. Extensive experiments on benchmark and real-world datasets
demonstrate the superiority of our methods over existing baselines. In
particular, our method outperforms DivideMix by 3\% in test accuracy. Source
code will be released soon.
