stat441w18/Saliency-based Sequential Image Attention with Multiset Prediction

Presented by

1. Alice Wang

2. Robert Huang

3. Yufeng Wang

4. Renato Ferreira

5. Being Fan

6. Xiaoni Lang

7. Xukun Liu

8. Handi Gao

Introduction

We are able to achieve high performances in image classification using current techniques, however, the techniques often exhibit unexpected and unintuitive behaviour, allowing minor perturbations to cause a complete misclassification. In addition, the classifier may accurately classify the image, while completely missing the object in question (for example, classifying an image containing a polar bear correctly because of the snowy setting).

To remedy this, we can either isolate the object and its surroundings and re-evaluate whether the classifier still performs adequately, or we can apply a saliency detection method to determine the focus of the classifier, and to understand how the classifier makes its decisions.

A commonly used method for saliency detection takes an image, then recursively removes sections of the image and evaluates the impact on the accuracy of the classification. The smallest region that causes the biggest impact on the classification score makes up our saliency map. However, this iterative method is computationally intensive and thus time-consuming.

This paper proposes a new saliency detection method that uses a trained model to predict the saliency map from a single feed-forward pass. The resulting saliency detection is not only order of magnitudes faster, but benchmarks against standard saliency detection methods also show that we have produced higher quality saliency masks and achieved better localization results.