PANORAMA: Panoptic Grounded Captioning via Mask Proposal Selection
Researchers introduce PANORAMA, a vision-language model grounding caption phrases in pixel masks, alongside the PanoCaps benchmark and gPQ metric.
The paper studies panoptic grounded captioning, requiring VLMs to describe foreground and background regions while grounding each phrase with pixel-level masks. The authors release PanoCaps, a human-annotated benchmark built from panoptic segmentation datasets, plus a phrase-mask matching protocol and a generalized Panoptic Quality (gPQ) metric. PANORAMA formulates grounding as selection from phrase-conditioned mask proposals generated by a pretrained segmenter, achieving the best overall grounding on PanoCaps and matching or exceeding specialized models. Code, data, and models are publicly available.
- PanoCaps offers dense captions with near-complete pixel coverage and entity-level image-text alignment.
- Phrase grounding is cast as selection from phrase-conditioned mask proposals.
- gPQ metric jointly evaluates textual and mask agreement.
- Joint training with caption generation preserves detailed, mask-consistent captions.
Full article251 words · extracted from huggingface.co · click to collapse
Intelligent systems that act in the world require image understanding that is both comprehensive and spatially grounded. Current vision-language models (VLMs) can generate fluent and detailed image captions, but reliably associating them with image pixels remains challenging. Existing methods that combine dense captioning with pixel-level grounding often produce either incomplete descriptions or inaccurate segmentation masks. We study this problem through panoptic grounded captioning, a task that requires a VLM to describe both foreground objects and background regions while grounding each referring phrase with pixel-level masks. We make three contributions. First, we introduce PanoCaps, a human-annotated benchmark constructed from panoptic segmentation datasets. It provides dense captions with near-complete pixel coverage and image-text alignments at the entity level, supporting both training and evaluation. We further propose a phrase-mask matching protocol and a generalized Panoptic Quality (gPQ) metric that jointly evaluates textual and mask agreement. Second, we formulate phrase grounding as selection from a phrase-conditioned pool of mask proposals and introduce PANORAMA, a VLM that conditions a pretrained segmenter on contextualized phrase representations to obtain candidate masks and learns to select those corresponding to each phrase. Training this interface jointly with caption generation enables PANORAMA to produce high-quality masks while allowing each phrase to refer to a single region or multiple instances. Third, PANORAMA achieves the best overall grounding on PanoCaps and matches or exceeds specialized models across several pixel-level grounding tasks. Experiments show that our method produces precise entity-level segmentations while maintaining detailed, mask-consistent captions. Code, data and models are available at https://www.di.ens.fr/willow/research/panorama/.
Text extracted automatically; images, tables and formatting may be missing. Original: https://huggingface.co/papers/2609.19143