VGDiffZero: Text-to-image Diffusion Models Can Be Zero-shot Visual Grounders
Xuyang Liu, Siteng Huang, Yachen Kang, Honggang Chen, Donglin Wang
TL;DR
Zero-shot visual grounding addresses object localization from natural language without task-specific annotations. This work demonstrates that pre-trained text-to-image diffusion models can be repurposed for grounding by a two-stage framework of Noise Injection and Noise Prediction, scoring proposals with $e_\text{total}=e_\text{mask}+e_\text{crop}$. The VGDiffZero approach leverages isolated global and local contexts, Faster R-CNN proposals, and CLIP text embeddings to achieve strong zero-shot results on RefCOCO, RefCOCO+, and RefCOCOg, illustrating the viability of diffusion-based vision-language models for discriminative tasks and reducing the need for costly fine-tuning.
Abstract
Large-scale text-to-image diffusion models have shown impressive capabilities for generative tasks by leveraging strong vision-language alignment from pre-training. However, most vision-language discriminative tasks require extensive fine-tuning on carefully-labeled datasets to acquire such alignment, with great cost in time and computing resources. In this work, we explore directly applying a pre-trained generative diffusion model to the challenging discriminative task of visual grounding without any fine-tuning and additional training dataset. Specifically, we propose VGDiffZero, a simple yet effective zero-shot visual grounding framework based on text-to-image diffusion models. We also design a comprehensive region-scoring method considering both global and local contexts of each isolated proposal. Extensive experiments on RefCOCO, RefCOCO+, and RefCOCOg show that VGDiffZero achieves strong performance on zero-shot visual grounding. Our code is available at https://github.com/xuyang-liu16/VGDiffZero.
