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Main Authors: Fang, Pengcheng, Chen, Hongli, Chen, Yuxia, Sun, Tengjiao, Liu, Jiaxin, Cai, Xiaohao
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.14727
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author Fang, Pengcheng
Chen, Hongli
Chen, Yuxia
Sun, Tengjiao
Liu, Jiaxin
Cai, Xiaohao
author_facet Fang, Pengcheng
Chen, Hongli
Chen, Yuxia
Sun, Tengjiao
Liu, Jiaxin
Cai, Xiaohao
contents Spectral token mixers based on Fourier transforms provide an efficient way to model global interactions in visual feature maps. Existing designs often either apply filter-wise spectral responses along fixed channel axes, or learn adaptive frequency-indexed channel mixing without explicitly aligning the channel directions used across frequencies. We propose CHASM, a Cross-frequency Harmonized Axis-Separable Mixer, as a structured middle ground. CHASM separates what should be shared from what should remain frequency-specific: all frequencies share a learned channel eigenbasis, while each frequency retains its own positive spectral gains. The shared basis makes channel directions comparable across the spectrum, whereas the positive gains preserve local spectral adaptivity. CHASM applies this structured operator separably along the height and width axes and is used as a drop-in replacement mixer inside existing backbones. We provide a structural characterization of the shared-basis operator family and evaluate CHASM through controlled same-backbone comparisons. Across accelerated MRI reconstruction, undersampled MRI segmentation, and natural-image reconstruction, CHASM consistently improves over same-backbone spectral-mixer baselines. Ablations show that removing the shared-basis constraint weakens performance, and randomizing coherent sampling geometry substantially reduces the gain, supporting cross-frequency harmonization as a useful inductive bias for spectral token operators.
format Preprint
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CHASM: Cross-frequency Harmonized Axis-Separable Mixing for Spectral Token Operators
Fang, Pengcheng
Chen, Hongli
Chen, Yuxia
Sun, Tengjiao
Liu, Jiaxin
Cai, Xiaohao
Computer Vision and Pattern Recognition
Spectral token mixers based on Fourier transforms provide an efficient way to model global interactions in visual feature maps. Existing designs often either apply filter-wise spectral responses along fixed channel axes, or learn adaptive frequency-indexed channel mixing without explicitly aligning the channel directions used across frequencies. We propose CHASM, a Cross-frequency Harmonized Axis-Separable Mixer, as a structured middle ground. CHASM separates what should be shared from what should remain frequency-specific: all frequencies share a learned channel eigenbasis, while each frequency retains its own positive spectral gains. The shared basis makes channel directions comparable across the spectrum, whereas the positive gains preserve local spectral adaptivity. CHASM applies this structured operator separably along the height and width axes and is used as a drop-in replacement mixer inside existing backbones. We provide a structural characterization of the shared-basis operator family and evaluate CHASM through controlled same-backbone comparisons. Across accelerated MRI reconstruction, undersampled MRI segmentation, and natural-image reconstruction, CHASM consistently improves over same-backbone spectral-mixer baselines. Ablations show that removing the shared-basis constraint weakens performance, and randomizing coherent sampling geometry substantially reduces the gain, supporting cross-frequency harmonization as a useful inductive bias for spectral token operators.
title CHASM: Cross-frequency Harmonized Axis-Separable Mixing for Spectral Token Operators
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.14727