ENACT: Entropy-based Clustering of Attention Input for Improving the Computational Performance of Object Detection Transformers

Transformers demonstrate competitive performance in terms of precision on the problem of vision-based object detection. However, they require considerable computational resources due to the quadratic size of the attention weights. In this work, we propose to cluster the transformer input on the basis of its entropy. The reason for this is that the self-information of each pixel (whose sum is the entropy), is likely to be similar among pixels corresponding to the same objects. Clustering reduces the size of data given as input to the transformer and therefore reduces training time and GPU memory usage, while at the same time preserves meaningful information to be passed through the remaining parts of the network. The proposed process is organized in a module called ENACT, that can be plugged-in any transformer architecture that consists of a multi-head self-attention computation in its encoder. We ran extensive experiments using the COCO object detection dataset, and three detection transformers. The obtained results demonstrate that in all tested cases, there is consistent reduction in the required computational resources, while the precision of the detection task is only slightly reduced. The code of the ENACT module will become available at https://github.com/GSavathrakis/ENACT