What-Where Transformer: A Slot-Centric Visual Backbone for Concurrent Representation and Localization

Fuente: arXiv
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Main Authors: Yoshihashi, Ryota, Kada, Masahiro, Ikehata, Satoshi, Kawakami, Rei, Sato, Ikuro
Format: Preprint
Published: 2026
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author Yoshihashi, Ryota
Kada, Masahiro
Ikehata, Satoshi
Kawakami, Rei
Sato, Ikuro
author_facet Yoshihashi, Ryota
Kada, Masahiro
Ikehata, Satoshi
Kawakami, Rei
Sato, Ikuro
contents Many image understanding tasks involve identifying what is present and where it appears. However, tasks that address where, such as object discovery, detection, and segmentation, are often considerably more complex than image classification, which primarily focuses on what. One possible reason is that classification-oriented backbones tend to emphasize semantic information about what, while implicitly entangling or suppressing information about where. In this work, we focus on an inductive bias termed what-where separation, which encourages models to represent object appearance and spatial location in a decomposed manner. To incorporate this bias throughout an attentive backbone in the style of Vision Transformer (ViT), we propose the What-Where Transformer (WWT). Our method introduces two key novel designs: (1) it treats tokens as representations of what and attention maps as representations of where, and processes them in concurrent feed-forward modules via a multi-stream, slot-based architecture; (2) it reuses both the final-layer tokens and attention maps for downstream tasks, and directly exposes them to gradients derived from task losses, thereby facilitating more effective and explicit learning of localization. We demonstrate that even under standard single-label classification-based supervision on ImageNet, WWT exhibits emergent multiple object discovery directly from raw attention maps, rather than via additional postprocessing such as token clustering. Furthermore, WWT achieves superior performance compared to ViT-based methods on zero-shot object discovery and weakly supervised semantic segmentation, and it is transferable to various localization setups with minimal modifications. Code will be published after acceptance.
format Preprint
id arxiv_https___arxiv_org_abs_2605_12021
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle What-Where Transformer: A Slot-Centric Visual Backbone for Concurrent Representation and Localization
Yoshihashi, Ryota
Kada, Masahiro
Ikehata, Satoshi
Kawakami, Rei
Sato, Ikuro
Computer Vision and Pattern Recognition
Many image understanding tasks involve identifying what is present and where it appears. However, tasks that address where, such as object discovery, detection, and segmentation, are often considerably more complex than image classification, which primarily focuses on what. One possible reason is that classification-oriented backbones tend to emphasize semantic information about what, while implicitly entangling or suppressing information about where. In this work, we focus on an inductive bias termed what-where separation, which encourages models to represent object appearance and spatial location in a decomposed manner. To incorporate this bias throughout an attentive backbone in the style of Vision Transformer (ViT), we propose the What-Where Transformer (WWT). Our method introduces two key novel designs: (1) it treats tokens as representations of what and attention maps as representations of where, and processes them in concurrent feed-forward modules via a multi-stream, slot-based architecture; (2) it reuses both the final-layer tokens and attention maps for downstream tasks, and directly exposes them to gradients derived from task losses, thereby facilitating more effective and explicit learning of localization. We demonstrate that even under standard single-label classification-based supervision on ImageNet, WWT exhibits emergent multiple object discovery directly from raw attention maps, rather than via additional postprocessing such as token clustering. Furthermore, WWT achieves superior performance compared to ViT-based methods on zero-shot object discovery and weakly supervised semantic segmentation, and it is transferable to various localization setups with minimal modifications. Code will be published after acceptance.
title What-Where Transformer: A Slot-Centric Visual Backbone for Concurrent Representation and Localization
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2605.12021