I Saw: A Self-Attention Weighted Method for Explanation of Visual Transformers

Abstract

Recently, visual transformers have shown promising results in tasks such as image classification, segmentation, object detection, etc. The explanation of their decision remains a challenge. This paper focuses on exploiting self-attention for an explanation. We propose a generalized interpretation of the transformers i.e model agnostic but class-specific explanations. The main principle is in the use and weighting self-attention maps of a visual transformer. To evaluate it, we use the popular hypothesis that an explanation is good if it correlates with human perception of a visual scene. Thus, the method has been evaluated against the Gaze Fixation Density Maps obtained in a psycho-visual experiment on a public database. It has been compared with other popular explainers such as Grad-Cam, LRP, Rollout, and Adaptive Relevance methods. The proposed method outperforms the best baseline by 2% in a standard Pearson Correlation Coefficient (PCC) metric.