Take 5: Interpretable Image Classification with a Handful of Features

Abstract

Deep Neural Networks use thousands of mostly incomprehensible features to identify a single class, a decision no human can follow. We propose an interpretable sparse and low dimensional final decision layer in a deep neural network with measurable aspects of interpretability and demonstrate it on fine-grained image classification. We argue that a human can only understand the decision of a machine learning model, if the features are interpretable and only very few of them are used for a single decision. For that matter, the final layer has to be sparse and -to make interpreting the features feasible -low dimensional. We call a model with a Sparse Low-Dimensional Decision "SLDD-Model". We show that a SLDD-Model is easier to interpret locally and globally than a dense high-dimensional decision layer while being able to maintain competitive accuracy. Additionally, we propose a loss function that improves a model's feature diversity and accuracy. Our more interpretable SLDD-Model only uses 5 out of just 50 features per class, while maintaining 97 % to 100 % of the accuracy on four common benchmark datasets compared to the baseline model with 2048 features. Figure 1: Local explanation by our SLDD-Model: The two features used for the predicted class, emerged without additional supervision, are aligned with human interpretable attributes and localized (described in App. D) adequately. 36th Conference on Neural Information Processing Systems (NeurIPS 2022).