Learning to classify images without explicit human annotations

Image classification problems today are often solved by first collecting examples along with candidate labels, second obtaining clean labels from workers, and third training a large, overparameterized deep neural network on the clean examples. The second, manual labeling step is often the most expensive one as it requires manually going through all examples. In this thesis we propose to i) skip the manual labeling step entirely, ii) directly train the deep neural network on the noisy candidate labels, and iii) early stop the training to avoid overfitting. With this procedure we exploit an intriguing property of overparameterized neural networks: While they are capable of perfectly fitting the noisy data, gradient descent fits clean labels faster than noisy ones. Thus, training and early stopping on noisy labels resembles training on clean labels only. Our results show that early stopping the training of standard deep networks (such as ResNet-18) on a subset of the Tiny Images dataset (which is obtained without any explicit human labels and only about half of the labels are correct), gives a significantly higher test performance than when trained on the clean CIFAR-10 training dataset (which is obtained by labeling a subset of the Tiny Images dataset). We also demonstrate that the performance gains are consistent across all the classes and are not a result of trivial or non-trivial overlaps between the datasets. In addition, our results show that the noise generated through the label collection process is not nearly as adversarial for learning as the noise generated by randomly flipping labels, which is the noise most prevalent in works demonstrating noise robustness of neural networks. We also confirm that our results continue to hold for other datasets by considering the large-scale problem of classifying a sub-set of the ImageNet with the images we obtain from Flickr, only by keyword searches and without any manual labeling.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Engineering

Grantor

Rice University

Year dc:date.issued

2020

Author dc:creator

• Yilmaz, Fatih Furkan

Advisors dc:contributor.advisor

• Heckel, Reinhard
• Veeraraghavan, Ashok

• Image classification
• Deep Neural Networks
• Early stopping
• Inductive bias
• Overparameterized models
• Learning from noisy labels

Statement dc:rights

• Copyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1911/108339

OAI identifier oai:identifier

oai:repository.rice.edu:1911/108339