  In this work, we propose a novel approach to densely ground visual entities
from a long caption. We leverage a large multimodal model (LMM) to extract
semantic nouns, a class-agnostic segmentation model to generate entity-level
segmentation, and the proposed multi-modal feature fusion module to associate
each semantic noun with its corresponding segmentation mask. Additionally, we
introduce a strategy of encoding entity segmentation masks into a colormap,
enabling the preservation of fine-grained predictions from features of
high-resolution masks. This approach allows us to extract visual features from
low-resolution images using the CLIP vision encoder in the LMM, which is more
computationally efficient than existing approaches that use an additional
encoder for high-resolution images. Our comprehensive experiments demonstrate
the superiority of our method, outperforming state-of-the-art techniques on
three tasks, including panoptic narrative grounding, referring expression
segmentation, and panoptic segmentation.
