One Channel to Rule Them All: Rethinking Input Representation for Visual Place Recognition

Fuente: arXiv
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Autores principales: Ismagilov, Timur, Majeed, Shakaiba, Milford, Michael, Nguyen, Tan Viet Tuyen, Ramchurn, Sarvapali D., Ehsan, Shoaib
Formato: Preprint
Publicado: 2026
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author Ismagilov, Timur
Majeed, Shakaiba
Milford, Michael
Nguyen, Tan Viet Tuyen
Ramchurn, Sarvapali D.
Ehsan, Shoaib
author_facet Ismagilov, Timur
Majeed, Shakaiba
Milford, Michael
Nguyen, Tan Viet Tuyen
Ramchurn, Sarvapali D.
Ehsan, Shoaib
contents Visual Place Recognition (VPR) is fundamental to long-term robot localization and SLAM, yet current systems overwhelmingly rely on RGB input, implicitly assuming color is necessary for global place recognition. We challenge this assumption, investigating the role of chromatic information across training regimes, model architectures and standard benchmarks under real-world appearance variation. We find that grayscale matches RGB performance generally and outperforms it under severe appearance shifts where color invariance is insufficiently learned, while color provides meaningful gains only where persistent and discriminative chromatic cues are present. Across selected benchmarks, a fully gray-trained MixVPR model achieves an average 82.4% Recall@1 compared to 81.2% for its RGB counterpart. In some cases, lightweight grayscale variants with 60% fewer parameters can outperform heavier RGB models. Grayscale further offers practical advantages in storage, bandwidth and alignment with resource-constrained systems. We conclude that for global VPR where scenes vary across illumination, weather, season and setting, color contributes minimally, and grayscale alone is sufficient for reliable place recognition.
format Preprint
id arxiv_https___arxiv_org_abs_2606_00936
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle One Channel to Rule Them All: Rethinking Input Representation for Visual Place Recognition
Ismagilov, Timur
Majeed, Shakaiba
Milford, Michael
Nguyen, Tan Viet Tuyen
Ramchurn, Sarvapali D.
Ehsan, Shoaib
Computer Vision and Pattern Recognition
Visual Place Recognition (VPR) is fundamental to long-term robot localization and SLAM, yet current systems overwhelmingly rely on RGB input, implicitly assuming color is necessary for global place recognition. We challenge this assumption, investigating the role of chromatic information across training regimes, model architectures and standard benchmarks under real-world appearance variation. We find that grayscale matches RGB performance generally and outperforms it under severe appearance shifts where color invariance is insufficiently learned, while color provides meaningful gains only where persistent and discriminative chromatic cues are present. Across selected benchmarks, a fully gray-trained MixVPR model achieves an average 82.4% Recall@1 compared to 81.2% for its RGB counterpart. In some cases, lightweight grayscale variants with 60% fewer parameters can outperform heavier RGB models. Grayscale further offers practical advantages in storage, bandwidth and alignment with resource-constrained systems. We conclude that for global VPR where scenes vary across illumination, weather, season and setting, color contributes minimally, and grayscale alone is sufficient for reliable place recognition.
title One Channel to Rule Them All: Rethinking Input Representation for Visual Place Recognition
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2606.00936