A Hypertoroidal Covering for Perfect Color Equivariance

Fuente: arXiv
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Main Authors: Yang, Yulong, Xu, Zhikun, Li, Yaojun, Allen-Blanchette, Christine
Format: Preprint
Published: 2026
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author Yang, Yulong
Xu, Zhikun
Li, Yaojun
Allen-Blanchette, Christine
author_facet Yang, Yulong
Xu, Zhikun
Li, Yaojun
Allen-Blanchette, Christine
contents When the color distribution of input images changes at inference, the performance of conventional neural network architectures drops considerably. A few researchers have begun to incorporate prior knowledge of color geometry in neural network design. These color equivariant architectures have modeled hue variation with 2D rotations, and saturation and luminance transformations as 1D translations. While this approach improves neural network robustness to color variations in a number of contexts, we find that approximating saturation and luminance (interval valued quantities) as 1D translations introduces appreciable artifacts. In this paper, we introduce a color equivariant architecture that is truly equivariant. Instead of approximating the interval with the real line, we lift values on the interval to values on the circle (a double-cover) and build equivariant representations there. Our approach resolves the approximation artifacts of previous methods, improves interpretability and generalizability, and achieves better predictive performance than conventional and equivariant baselines on tasks such as fine-grained classification and medical imaging tasks. Going beyond the context of color, we show that our proposed lifting can also extend to geometric transformations such as scale.
format Preprint
id arxiv_https___arxiv_org_abs_2603_04256
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle A Hypertoroidal Covering for Perfect Color Equivariance
Yang, Yulong
Xu, Zhikun
Li, Yaojun
Allen-Blanchette, Christine
Computer Vision and Pattern Recognition
When the color distribution of input images changes at inference, the performance of conventional neural network architectures drops considerably. A few researchers have begun to incorporate prior knowledge of color geometry in neural network design. These color equivariant architectures have modeled hue variation with 2D rotations, and saturation and luminance transformations as 1D translations. While this approach improves neural network robustness to color variations in a number of contexts, we find that approximating saturation and luminance (interval valued quantities) as 1D translations introduces appreciable artifacts. In this paper, we introduce a color equivariant architecture that is truly equivariant. Instead of approximating the interval with the real line, we lift values on the interval to values on the circle (a double-cover) and build equivariant representations there. Our approach resolves the approximation artifacts of previous methods, improves interpretability and generalizability, and achieves better predictive performance than conventional and equivariant baselines on tasks such as fine-grained classification and medical imaging tasks. Going beyond the context of color, we show that our proposed lifting can also extend to geometric transformations such as scale.
title A Hypertoroidal Covering for Perfect Color Equivariance
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2603.04256