Open-vocabulary Semantic Segmentation with Frozen Vision-Language Models

Chaofan Ma (Shanghai Jiao Tong University), Yuhuan Yang (Shanghai Jiao Tong University), Yan-Feng Wang (Cooperative medianet innovation center of Shanghai Jiao Tong University), Ya Zhang (Cooperative Medianet Innovation Center, Shang hai Jiao Tong University), Weidi Xie (Shanghai Jiao Tong University)*
The 33rd British Machine Vision Conference


When trained at a sufficient scale, self-supervised learning has exhibited a notable ability to solve a wide range of visual or language understanding tasks. In this paper, we investigate simple, yet effective approaches for adapting the pre-trained foundation models to the downstream task of interest, namely, open-vocabulary semantic segmentation. To this end, we make the following contributions: (i) we introduce Fusioner, with a lightweight, transformer-based fusion module, that pairs the frozen visual representation with language concept through a handful of image segmentation data, as a consequence, the model gains the capability of zero-shot transfer to segment novel categories; (ii) without loss of generality, we experiment on a broad range of self-supervised models that have been pre-trained with different schemes, e.g. visual-only models (MoCo v3, DINO), language-only models (BERT), visual-language model (CLIP), and show that, the proposed fusion approach is effective to any pair of visual and language models, even those pre-trained on a corpus of uni-modal data; (iii) we conduct thorough ablation studies to analyze the critical components in our proposed Fusioner, while evaluating on standard benchmarks, e.g. PASCAL-5i and COCO-20i, it surpasses existing state-of-the-art models by a large margin, despite only being trained on frozen visual and language features; (iv) to measure the model's robustness on learning visual-language correspondence, we further evaluate on a synthetic dataset, named Mosaic-4, where images are constructed by mosaicking the samples from FSS-1000. Fusioner demonstrates superior performance over previous models.



author    = {Chaofan Ma and Yuhuan Yang and Yan-Feng Wang and Ya Zhang and Weidi Xie},
title     = {Open-vocabulary Semantic Segmentation with Frozen Vision-Language Models},
booktitle = {33rd British Machine Vision Conference 2022, {BMVC} 2022, London, UK, November 21-24, 2022},
publisher = {{BMVA} Press},
year      = {2022},
url       = {}

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