Research map / Vision-language and multimodal / CLIP and zero-shot
Retrieval-Enhanced Contrastive Vision-Text Models
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Proposes RECO, which refines frozen CLIP/LiT embeddings with cross-modal knowledge retrieved from a large external image-text memory via a single-layer transformer fusion module trained on CC12M, improving zero-shot fine-grained recognition.
Problem
Contrastive vision-text models like CLIP struggle with fine-grained entities that are rare or absent from pre-training data; zero-shot performance on fine-grained recognition is weak.
Approach
Retrieve neighbours within the same modality (image-to-image, text-to-text) from a large image-text memory, then fuse the retrieved items of the opposite modality (captions for images, images for texts) into frozen embeddings with a light one-layer transformer fusion trained with contrastive losses that align refined and original embeddings.
Key results
- RECO on CLIP-B/32 improves zero-shot Cars from 57.2 to 68.1 (+10.9), CUB from 52.8 to 63.0 (+10.2) and Flowers by +5.8.
- On OVEN, CLIP-L/14 + RECO reaches 12.3 harmonic mean vs 5.3 for CLIP-L/14 zero-shot, outperforming fine-tuned PaLI-3B and CLIP2CLIP.
- Uni-modal search with cross-modal fusion gives +9.0% average relative improvement vs +1.7% for cross-modal search.
Measured effects reported in the paper
| What was changed | Where | Measured | Effect |
|---|---|---|---|
| add RECO retrieval and fusion | CLIP-B/32 · Cars | top-1 accuracy: 57.2 -> 68.1; +10.9 | Helped |
| add RECO retrieval and fusion | CLIP-B/32 · CUB | top-1 accuracy: 52.8 -> 63.0; +10.2 | Helped |
| add RECO retrieval and fusion | CLIP-B/32 · Flowers | top-1 accuracy: +5.8 | Helped |
| add RECO retrieval and fusion | CLIP-L/14 · OVEN unseen | top-1 accuracy: 4.9 -> 13.3 | Helped |
| add RECO retrieval and fusion | CLIP-B/32 · COCO T→I | recall@1: +3.4 | Helped |
| use uni-modal rather than cross-modal search (ablation) | Transformer cross-modal fusion · Cars, CUB, Flowers, ImageNet-1k, Places365 | average relative improvement over CLIP: +1.7 % -> +9.0 % | Helped |
| use cross-modal rather than uni-modal fusion (ablation) | Transformer fusion · Cars, CUB, Flowers, ImageNet-1k, Places365 | average relative improvement over CLIP: +9.0 % -> $-$ 0.4 %; $-$ 1.9 % | Mixed |
| replace learned Transformer fusion with mean fusion (ablation) | RECO · Cars, CUB, Flowers, ImageNet-1k, Places365 | average relative improvement over CLIP: $+$ 9.0 % -> $-$ 21.7 % | Hurt |
| train fusion for both image and text branches rather than text only (ablation) | RECO · CUB | top-1 accuracy: 59.3 -> 63.0 | Helped |
| train fusion for both image and text branches rather than image only (ablation) | RECO · COCO T→I | recall@1: 31.3 -> 33.6 | Mixed |
| replace RECO with a scratch-trained MLP layer (ablation) | CLIP-B/32 · CUB | top-1 accuracy | Hurt |
| use full WebLI memory at inference after training with 1% WebLI (ablation) | RECO · CUB | top-1 accuracy | Helped |
Surprising findings
- Cross-modal search (retrieving opposite-modality neighbours directly) gives much smaller gains, and uni-modal fusion can hurt performance.
- Training an extra MLP layer on CLIP with the same data yields no gain and even degrades performance, so gains are not due to extra training.
Limitations
- Requires access to a large, rich image-text memory; best results use a large private memory (WebLI), while public LAION-400M gives smaller gains.
- Retrieval increases inference time (about 25% overhead).
Experimental setup
Datasets: Conceptual Captions 12M WebLI LAION-400M Stanford Cars CUB-200-2011 Oxford Flowers ImageNet-1k Places365 Stanford Dogs OVEN Flickr30k MS COCO
Benchmarks: Stanford Cars CUB-200-2011 Oxford Flowers ImageNet-1k Places365 Stanford Dogs OVEN Flickr30k MS COCO
Metrics: top-1 accuracy recall@1 harmonic mean
Baselines: CLIP LiT K-LITE RA-CLIP Align PaLI-17B CLIP2CLIP PaLI-3B FLAVA SuS-X
Builds on: CLIP LiT InfoNCE K-LITE RA-CLIP
Closest papers by meaning
- Building Vision-Language Models on Solid Foundations with Masked Distillation (CVPR 2024 · similarity 0.90)
- Rethinking Contrastive Loss in CLIP Post-training: A Complementary Framework with Frozen Text Encoder (NeurIPS 2026 · similarity 0.89)
- Unified Generative and Discriminative Training for Multi-modal Large Language Models (NeurIPS 2024 · similarity 0.89)
- AmorLIP: Efficient Language-Image Pretraining via Amortization (NeurIPS 2025 · similarity 0.89)
- Post-pre-training for Modality Alignment in Vision-Language Foundation Models (CVPR 2025 · similarity 0.89)
- FineCLIP: Self-distilled Region-based CLIP for Better Fine-grained Understanding (NeurIPS 2024 · similarity 0.88)
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