This paper addresses the challenging problem of open-vocabulary object detection (OVOD) where an object detector must identify both seen and unseen classes in test images without labeled examples of the unseen classes in training. A typical approach for OVOD is to use joint text-image embeddings of CLIP to assign box proposals to their closest text label. However, this method has a critical issue: many low-quality boxes, such as over- and under-covered-object boxes, have the same similarity score as high-quality boxes since CLIP is not trained on exact object location information. To address this issue, we propose a novel method, LP-OVOD, that discards low-quality boxes by training a sigmoid linear classifier on pseudo labels retrieved from the top relevant region proposals to the novel text. Experimental results on COCO affirm the superior performance of our approach over the state of the art, achieving $\textbf{40.5}$ in $\text{AP}_{novel}$ using ResNet50 as the backbone and without external datasets or knowing novel classes during training. Our code will be available at https://github.com/VinAIResearch/LP-OVOD.

本文提出了一种解决开放词汇物体检测（OVOD）问题的方法，该方法使用共同的文本图像嵌入来为边界提案分配最接近的文本标签，并通过从前n个相关区域提案中检索伪标签来训练一个分类器以丢弃低质量的边界框，实验证明我们的方法在COCO数据集上比现有方法表现优秀，AP_novel达到了40.5。

LP-OVOD：通过线性探测的开放词汇物体检测