FG-CLIP: Fine-Grained Visual and Textual Alignment
Authors: name: Chunyu Xie, name: Bin Wang, name: Fanjing Kong, name: Jincheng Li, name: Dawei Liang, name: Gengshen Zhang, name: Dawei Leng, name: Yuhui Yin

Contrastive Language-Image Pre-training (CLIP) excels in multimodal tasks
such as image-text retrieval and zero-shot classification but struggles with
fine-grained understanding due to its focus on coarse-grained short captions.
To address this, we propose Fine-Grained CLIP (FG-CLIP), which enhances
fine-grained understanding through three key innovations. First, we leverage
large multimodal models to generate 1.6 billion long caption-image pairs for
capturing global-level semantic details. Second, a high-quality dataset is
constructed with 12 million images and 40 million region-specific bounding
boxes aligned with detailed captions to ensure precise, context-rich
representations. Third, 10 million hard fine-grained negative samples are
incorporated to improve the model's ability to distinguish subtle semantic
differences. Corresponding training methods are meticulously designed for these
data. Extensive experiments demonstrate that FG-CLIP outperforms the original
CLIP and other state-of-the-art methods across various downstream tasks,
including fine-grained understanding, open-vocabulary object detection,
image-text retrieval, and general multimodal benchmarks. These results
highlight FG-CLIP's effectiveness in capturing fine-grained image details and
improving overall model performance. The related data, code, and models are
available at https://github.com/360CVGroup/FG-CLIP.