Person re-identification (ReID) ranks an image gallery using either an image query or a textual query. In image-to-image (I2I) ReID, viewpoint, illumination, occlusion, and background changes can make distractors appear more similar than the true match. In text-to-image (T2I) ReID, incomplete or ambiguous descriptions may omit key visual evidence. We study this problem for vision-language model (VLM) based ReID, where attributes such as clothing color and carried objects provide useful fine-grained matching cues. However, directly using attribute-prompt similarities as retrieval scores is unreliable because templated prompts can be biased, correlated, and poorly calibrated. We therefore propose PRompt-guided Attribute-based Inference-time Similarity Enhancement (PRAISE), a query-side test-time adaptation framework for VLM-based ReID. Instead of treating prompts as scores, PRAISE uses a transferable attribute-prompt bank to construct an Attribute-Conditioned Subspace (ACS): a query-dependent low-rank subspace induced by the most compatible attribute prompts. ACS provides a controlled attribute-conditioned geometry for reshaping query--gallery affinities and guiding lightweight inference-time updates without identity or attribute labels. Experiments across multiple I2I- and T2I-ReID benchmarks show that PRAISE consistently improves VLM retrieval backbones and outperforms both generic and ReID-specific TTA baselines.
Figures & tables
Figure 1: Motivation and overview of PRAISE . (a) In I2I-ReID, raw visual similarity can retrieve distractors caused by camera, pose, or background bias. (b) In T2I-ReID, incomplete text descriptions can produce partial matches that share only some mentioned attributes. (c) PRAISE addresses both cases by selecting query-relevant attribute directions, orthogonalizing them into an Attribute-Conditioned Subspace (ACS), and using this controlled subspace to reshape query-gallery affinities during test-time.
Figure 2: Similarity distributions for matching and non-matching query-gallery pairs on Market-1501. Direct prompt-profile similarity (a) is saturated for both groups, whereas ACS (b) yields clearer separation between matches and distractors.
Figure 3: Method overview. PRAISE uses attribute prompts to construct a query-specific semantic subspace that stabilizes query-side adaptation under domain shift. At test time, it performs query-side episodic TTA with a fixed source-space gallery index. Gallery and prompt-bank embeddings are computed once and kept fixed; gradients update only the query-side normalization affine parameters.
Backbone
I2IReID
T2IReID
MSMT17
Market-1501
CUHK-Pedes
RSTPReID
mAP
R1
mAP
R1
mAP
R1
mAP
R1
CLIP ViT-B/16 [ 35 ]
0 1.1 / 0 1.4
0 5.6 / 0 6.7
0 3.5 / 0 4.3
11.9 / 14.0
0 7.1 / 0 9.1
0 8.9 / 11.7
0 8.1 / 0 9.2
11.2 / 12.9
DINO.txt [ 14 ]
0 0.7 / 0 1.8
0 5.2 / 0 9.4
0 1.9 / 0 3.0
0 7.1 / 10.1
0 7.3 / 0 8.8
0 9.1 / 12.8
10.3 / 13.1
11.9 / 14.6
CLIPReID [ 26 ]
20.8 / 24.7
45.9 / 52.8
37.8 / 42.1
63.3 / 69.4
0 8.1 / 0 9.9
0 8.2 / 11.4
12.2 / 13.8
13.5 / 15.1
RDE [ qin2024noisy ]
-
-
-
-
33.5 / 38.1
36.8 / 42.8
41.2 / 46.3
54.9 / 60.9
Table 1: Effect on different backbones. Backbones evaluated on I2IReID and T2IReID datasets with PRAISE applied (score on left side of ‘ / ’ is without adaptation and score on right is after applying PRAISE ). Each dataset reports mAP and Rank-1 Accuracy (R1).
TTA Method
Type
Dataset
Time (ms) / sample
MSMT17
Market-1501
mAP
R1
mAP
R1
No-adapt (Source) [NeurIPS’24]
–
10.5
34.2
35.0
62.6
0 1.8
TENT [ wang2020tent ] [ICLR’21]
Classifier logit
0 9.2
29.8
29.3
52.7
16.2
SHOT [ 27 ] [ICML’20]
0 9.9
30.2
28.9
56.8
63.8
SAR [ 29 ] [ICLR’23]
10.0
31.1
33.2
63.3
91.4
Table 2: Comparison of TTA methods on I2IReID benchmarks using a PLIP [ 55 ] backbone. Each dataset reports mAP and Rank-1 Accuracy (R1).
TTA Method
Type
Dataset
Time (ms) / sample
CUHK-Pedes
RSTPReID
mAP
R1
mAP
R1
No-adapt (Source) [NeurIPS’24]
–
46.4
55.9
23.1
34.5
12.9
TENT [ wang2020tent ] [ICLR’21]
Classifier logit
46.4
56.2
23.3
34.2
81.8
SHOT [ 27 ] [ICML’20]
47.1
56.6
24.2
34.0
179.1
TPT [ 36 ] [NeurIPS’22]
VLM based
46.5
55.9
23.1
34.6
4193.4
Table 3: Comparison of TTA methods on T2IReID benchmarks on a PLIP [ 55 ] backbone. Each dataset reports mAP and Rank-1 Accuracy (R1).
Figure 4: Hyperparameter Sensitivity. Performance with respect to varying hyperparameters. Tested on Market-1501.
Group
Variant
I2I-ReID
T2I-ReID
mAP
R1
mAP
R1
Component Ablation
No adapt
35.0
62.6
23.1
34.5
ACS only (No-adaptation, αacs=0.1 )
35.2
61.8
23.6
34.1
Adaptation w/o ACS (αacs=0)
36.8
65.0
23.5
35.4
ACS adaptation (i.e. PRAISE )
46.5
71.1
27.6
37.6
Subspace Ablation
Shuffled prompts across queries
37.8
62.8
23.5
35.3
Table 4: Ablations. All rows use the same TopR, rank r , number of adaptation steps, and αacs , unless stated otherwise. I2I-ReID results are reported on Market-1501 and T2I-ReID results on RSTPReID.
Appendix figures & tables14 assets
Supplementary material from the paper’s appendix.
Appendix
Figure 5: Retrieval Top-1 Error-rate distribution across entropy and cosine distance. Curves computed on the Market-1501 [ 52 ] dataset for I2I-ReID and RSTPReID [ 53 ] for T2I-ReID.
Figure 6: Understanding the nature of the embedding space between a query and gallery, and a theoretical interpretation of Figure 5 where error rate is a surrogate for e(r) .
Figure 7: Prompt-bank construction pipeline. (a) A VLM is used to caption unlabeled pedestrian images and extract recurring appearance cues. These cues are grouped into semantic categories and cleaned to remove duplicate or near-identical phrases. (b) The cleaned attribute suffixes are inserted into a shared template to form the final prompt bank P={sℓ}ℓ=1L , together with a neutral prompt s0 used for prompt centering.
TTA Method
Market-1501 (Corrupted)
Gaussian Noise
Poisson Noise
Defocus Blur
Motion Blur
Brightness
mAP
R1
mAP
R1
mAP
R1
mAP
R1
mAP
R1
No-adapt (Source) [NeurIPS’24]
24.2
50.7
14.5
37.5
13.7
35.7
8.9
26.1
33.5
60.9
TENT [ wang2020tent ] [ICLR’21]
23.4
48.0
9.0
22.6
11.5
34.2
6.9
19.9
29.7
55.3
SHOT [ 27 ] [ICML’20]
23.8
51.1
15.7
36.3
13.2
33.6
1.9
4.9
28.5
55.5
SAR [ 29 ] [ICLR’23]
26.6
52.2
16.8
38.8
14.2
35.0
8.7
24.3
31.8
58.1
Appendix
Table 5: Image Corruptions and Noise. Comparison of TTA methods on I2IReID using a PLIP [ 55 ] backbone. Results are reported on Market-1501 under five corruptions (mAP / R1).
Prompt-bank source
MSMT17
Market-1501
CUHK-PEDES
RSTP-ReID
mAP
R1
mAP
R1
mAP
R1
mAP
R1
No-adapt source model
10.5
34.2
35.0
62.6
46.4
55.9
23.1
34.5
Generic prompt bank
17.8
36.3
45.9
70.1
48.7
56.1
27.1
36.1
Market-1501 mined bank
18.2
38.5
46.5
71.1
49.6
58.4
27.6
37.6
MSMT17 mined bank
18.4
39.1
46.5
70.1
49.2
57.6
26.9
37.0
CUHK-PEDES mined bank
17.9
36.5
45.4
69.7
49.4
58.1
27.6
37.5
Appendix
Table 6: Effect of attribute prompt-bank source. We evaluate PRAISE using the same fixed hyperparameters while varying only the source used to construct the attribute prompt bank. The manual bank is hand-designed, while the remaining banks are mined from the corresponding ReID datasets using the same label-free captioning and cleaning protocol. Results show that PRAISE is not tied to a specific prompt-bank source and remains stable across transferable pedestrian attribute vocabularies.
Prompt-bank variant
Market-1501
RSTP-ReID
mAP
R1
mAP
R1
No-adapt source model
35.0
62.6
23.1
34.5
Full prompt bank
46.5
71.1
27.6
37.6
w/o upper-body color
45.8
68.1
26.1
35.2
w/o lower-body color
45.9
69.3
27.0
36.9
w/o upper-body clothing
46.0
69.5
27.2
37.4
Appendix
Table 7: Attribute-category ablation. We evaluate PRAISE using the same Market-1501 mined prompt bank and fixed hyperparameters, while removing one group of attributes at a time. This isolates which attribute categories contribute most to the query-conditioned ACS geometry.
TTA Method
I2I-ReID
Train: MSMT17
Train: Market-1501
Test: MSMT17
Test: Market-1501
Test: MSMT17
Test: Market-1501
mAP
R1
mAP
R1
mAP
R1
mAP
R1
No-adapt (Source)
57.4
79.9
37.8
63.3
21.0
46.9
83.6
92.6
TENT [ wang2020tent ] [ICLR’21]
55.2
75.4
35.2
60.5
18.6
44.2
82.1
91.1
SHOT [ 27 ] [ICML’20]
49.7
68.4
32.1
57.6
14.6
41.2
80.6
89.8
Appendix
Table 8: Comparison of TTA methods on I2I-ReID benchmarks using a source-trained CLIP-ReID [ 26 ] image encoder. All methods are evaluated under the same PRAISE-compatible cosine-retrieval protocol, with fixed gallery embeddings and no target identity labels.
TTA Method
T2I-ReID
Train: CUHK-PEDES
Train: RSTP-ReID
Test: CUHK
Test: RSTP
Test: CUHK
Test: RSTP
mAP
R1
mAP
R1
mAP
R1
mAP
R1
No-adapt (Source) [NeurIPS’24]
64.2
72.7
41.2
54.9
33.5
36.8
47.9
62.1
TENT [ wang2020tent ] [ICLR’21]
64.0
72.8
41.0
53.4
33.1
36.4
47.5
62.0
SHOT [ 27 ] [ICML’20]
64.5
72.9
41.3
54.7
33.8
37.1
48.3
62.5
Appendix
Table 9: Comparison of TTA methods on T2I-ReID benchmarks using source-trained RDE [ qin2024noisy ] backbones. All methods are evaluated under the same PRAISE-compatible cosine-retrieval protocol, with fixed gallery embeddings and no target identity labels.
Figure 8: Gallery-size scalability of PRAISE on MSMT17 with PLIP. Peak GPU-memory and adaptation-latency increases are reported relative to the 1k-gallery setting. The gallery is increased from 1,000 to the full 82,161 images while retaining the default adaptation batch size of 32. Even at the full gallery, peak memory increases by only 9.0% , while amortized per-query latency increases by 15.5% .
Figure 9: Sensitivity to initial retrieval quality on Market-1501. Queries are grouped by the initial rank of the first valid cross-camera match under the frozen PLIP baseline. Bars show the percentage of queries whose first-correct rank improves, remains unchanged, or degrades after PRAISE. The line reports mean ΔRR , where positive values indicate improved retrieval.
λatt
Market-1501
RSTPReID
0.0
36.8/65.0
23.5/35.4
0.1
39.2/60.3
24.5/32.9
0.2
38.9/60.1
24.3/32.5
0.5
37.5/58.7
23.7/30.8
1.0
35.1/54.5
23.1/28.3
Appendix
Table 10: Sensitivity to the direct attribute-fusion weight λatt . Results are reported as mAP/R1.
Figure 10: NMI comparison across methods.
Figure 11: Some success and failure cases for I2I-ReID from Market-1501 [ 52 ] dataset.
Figure 12: Some success and failure cases for T2I-ReID from RSTPReID [ 53 ] dataset.
Recent vision-language models such as CLIP provide strong cross-modal alignment, but current CLIP-guided ReID pipelines rely on global features and fixed prompts. This limits their ability to capture fine-grained attribute cues and adapt to diverse appearances. We propose ALADIN, an attribute-language distillation network that distills knowledge from a frozen CLIP teacher to a lightweight ReID student. ALADIN introduces fine-grained attribute-local alignment to establish adaptive text-visual correspondence and robust representation learning. A Scene-Aware Prompt Generator produces image-specific soft prompts to facilitate adaptive alignment. Attribute-local distillation enforces consistency between textual attributes and local visual features, significantly enhancing robustness under occlusions. Furthermore, we employ cross-modal contrastive and relation distillation to preserve the inherent structural relationships among attributes. To provide precise supervision, we leverage Multimodal LLMs to generate structured attribute descriptions, which are then converted into localized attention maps via CLIP. At inference, only the student is used. Experiments on Market-1501, DukeMTMC-reID, and MSMT17 show improvements over CNN-, Transformer-, and CLIP-based methods, with better generalization and interpretability.
Wang Zhou, Boran Duan, Haojun Ai +2
Wuhan University No.299 Bayi Road, 430072, PR China
Lifelong person re-identification (LReID) aims to learn from varying domains to obtain a unified person retrieval model. Existing LReID approaches typically focus on learning from scratch or a visual classification-pretrained model, while the Vision-Language Model (VLM) has shown generalizable knowledge in a variety of tasks. Although existing methods can be directly adapted to the VLM, since they only consider global-aware learning, the fine-grained attribute knowledge is underleveraged, leading to limited acquisition and anti-forgetting capacity. To address this problem, we introduce a novel VLM-driven LReID approach named Vision-Language Attribute Disentanglement and Reinforcement (VLADR). Our key idea is to explicitly model the universally shared human attributes to improve inter-domain knowledge transfer, thereby effectively utilizing historical knowledge to reinforce new knowledge learning and alleviate forgetting. Specifically, VLADR includes a Multi-grain Text Attribute Disentanglement mechanism that mines the global and diverse local text attributes of an image. Then, an Inter-domain Cross-modal Attribute Reinforcement scheme is developed, which introduces cross-modal attribute alignment to guide visual attribute extraction and adopts inter-domain attribute alignment to achieve fine-grained knowledge transfer. Experimental results demonstrate that our VLADR outperforms the state-of-the-art methods by 1.9%-2.2% and 2.1%-2.5% on anti-forgetting and generalization capacity. Our source code is available at https://github.com/zhoujiahuan1991/CVPR2026-VLADR
Kunlun Xu, Haotong Cheng, Jiangmeng Li +2
Wangxuan Institute of Computer Technology, Peking University, Beijing, China · University of Chinese Academy of Sciences, Beijing, China · School of Artificial Intelligence and Automation, Huazhong University of Science and Technology, Wuhan, China
Generalizable image-based person re-identification (Re-ID) aims to recognize individuals across cameras in unseen domains without retraining. While visual features are sensitive to domain shifts, natural language descriptions remain consistent across domains, regardless of lighting changes and other biases. Since well-known multi-camera datasets lack textual descriptions, we update them with captions through a fine-tuned Vision-Language Model (VLM). We propose ReText, a novel method trained with textual supervision to enrich visual features with semantic cues. Besides, inspired by recent findings showing that incorporating single-camera data into training improves generalization, we also adopt this strategy. However, in contrast to such prior works, we exploit not only visual information but also the textual annotations naturally accompanying these samples. Finally, during training, ReText jointly optimizes three tasks: (1) Re-ID, (2) image-text matching, and (3) image reconstruction guided by text. Experiments demonstrate that ReText achieves strong generalization and significantly outperforms state-of-the-art methods on cross-domain Re-ID benchmarks. The expanded multi-camera datasets and VLM weights are publicly available at https://github.com/timmzak/ReText.
Timur Mamedov, Karina Kvanchiani, Anton Konushin +1
Tevian, Moscow, Russia · Lomonosov Moscow State University