TIB: Detecting Unknown Objects via Two-Stream Information Bottleneck

Detecting diverse objects, including ones never-seen-before during training, is critical for the safe application of object detectors. To this end, a task of unsupervised out-of-distribution object detection (OOD-OD) is proposed to detect unknown objects without the reliance on an auxiliary dataset. For this task, it is important to reduce the impact of lacking unknown data for supervision and leverage in-distribution (ID) data to improve the model's discrimination. In this paper, we propose a method of Two-Stream Information Bottleneck (TIB), consisting of a standard IB and a dedicated Reverse Information Bottleneck (RIB). Specifically, after extracting the features of an ID image, we first define a standard IB network to disentangle instance representations that are beneficial for localizing and recognizing objects. Meanwhile, we present RIB to obtain simulative OOD features to alleviate the impact of lacking unknown data. Different from standard IB aiming to extract task-relevant compact representations, RIB is to obtain task-irrelevant representations by reversing the optimization objective of the standard IB. Next, to further enhance the discrimination, a mixture of information bottlenecks is designed to sufficiently capture object-related information. Experimental results on OOD-OD, open-vocabulary object detection, incremental object detection, and open-set object detection show the superiorities of our method.