CountSE: Soft Exemplar Open-set Object Counting

Open-set counting is garnering increasing attention due to its capability to enumerate objects of arbitrary category. It can be generally categorized into two methodologies: text-guided zero-shot counting methods and exemplar-guided few-shot counting methods. Previous text-guided zero-shot methods only provide limited object information through text, resulting in poor performance. Besides, though exemplar-guided few-shot approaches gain better results, they rely heavily on manually annotated visual exemplars, resulting in low efficiency and high labor intensity. Therefore, we propose CountSE, which simultaneously achieves high efficiency and high performance. CountSE is a new text-guided zero-shot object counting algorithm that generates multiple precise soft exemplars at different scales to enhance counting models driven solely by semantics. Specifically, to obtain richer object information and address the diversity in object scales, we introduce Semantic-guided Exemplar Selection, a module that generates candidate soft exemplars at various scales and selects those with high similarity scores. Then, to ensure accuracy and representativeness, Clustering-based Exemplar Filtering is introduced to refine the candidate exemplars by effectively eliminating inaccurate exemplars through clustering analysis. In the text-guided zero-shot setting, CountSE outperforms all state-of-the-art methods on the FSC-147 benchmark by at least 15\%. Additionally, experiments on two other widely used datasets demonstrate that CountSE significantly outperforms all previous text-guided zero-shot counting methods and is competitive with the most advanced exemplar-guided few-shot methods. Codes will be available.