RefCOCOg

RefCOCOg is a referring expression comprehension benchmark that evaluates spatial grounding in images. Given a natural language expression describing an object, the model must localize the correct region, evaluated by accuracy at a 0.5 IoU threshold. It features longer, more descriptive expressions than RefCOCO and RefCOCO+.

Nova 2 Omni from Amazon currently leads the RefCOCOg leaderboard with a score of 0.863 across 1 evaluated AI models.

Paper
About this benchmark

What RefCOCOg measures

RefCOCOg is a multimodal benchmark that evaluates large language models on multimodal, grounding, and vision tasks. LLM Stats tracks 1 model on this benchmark, with a maximum possible score of 1. Current average across reported models is 0.9, with the leader reaching 0.9.

Compare leaders on the best AI for multimodal, best AI for grounding and best AI for vision leaderboards.

Publication

Paper
Generation and Comprehension of Unambiguous Object Descriptions
Authors
Junhua Mao, Jonathan Huang, Alexander Toshev, Oana Camburu, and 2 others
Published

Abstract

We propose a method that can generate an unambiguous description (known as a referring expression) of a specific object or region in an image, and which can also comprehend or interpret such an expression to infer which object is being described. We show that our method outperforms previous methods that generate descriptions of objects without taking into account other potentially ambiguous objects in the scene. Our model is inspired by recent successes of deep learning methods for image captioning, but while image captioning is difficult to evaluate, our task allows for easy objective evaluation. We also present a new large-scale dataset for referring expressions, based on MS-COCO. We have released the dataset and a toolbox for visualization and evaluation, see https://github.com/mjhucla/Google_Refexp_toolbox

AmazonNova 2 Omni leads with 86.3%.

Progress Over Time

Interactive timeline showing model performance evolution on RefCOCOg

State-of-the-art frontier
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Proprietary

RefCOCOg Leaderboard

1 models
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1
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FAQ

Common questions about RefCOCOg.

What is the RefCOCOg benchmark?

RefCOCOg is a referring expression comprehension benchmark that evaluates spatial grounding in images. Given a natural language expression describing an object, the model must localize the correct region, evaluated by accuracy at a 0.5 IoU threshold. It features longer, more descriptive expressions than RefCOCO and RefCOCO+.

What is the RefCOCOg leaderboard?

The RefCOCOg leaderboard ranks 1 AI models based on their performance on this benchmark. Currently, Nova 2 Omni by Amazon leads with a score of 0.863. The average score across all models is 0.863.

What is the highest RefCOCOg score?

The highest RefCOCOg score is 0.863, achieved by Nova 2 Omni from Amazon.

How many models are evaluated on RefCOCOg?

1 models have been evaluated on the RefCOCOg benchmark, with 0 verified results and 1 self-reported results.

Where can I find the RefCOCOg paper?

The RefCOCOg paper is available at https://arxiv.org/abs/1511.02283. The paper details the methodology, dataset construction, and evaluation criteria.

What categories does RefCOCOg cover?

RefCOCOg is categorized under multimodal, grounding, and vision. The benchmark evaluates multimodal models.

How recent are the RefCOCOg leaderboard results?

The RefCOCOg leaderboard was last updated in June 2026 and currently includes 1 evaluated models.

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