Multi-scale Image Super Resolution with a Single Auto-Regressive Model

Fuente: arXiv
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Main Authors: Sanchez, Enrique, Hadji, Isma, Bulat, Adrian, Tzelepis, Christos, Martinez, Brais, Tzimiropoulos, Georgios
Format: Preprint
Published: 2025
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author Sanchez, Enrique
Hadji, Isma
Bulat, Adrian
Tzelepis, Christos
Martinez, Brais
Tzimiropoulos, Georgios
author_facet Sanchez, Enrique
Hadji, Isma
Bulat, Adrian
Tzelepis, Christos
Martinez, Brais
Tzimiropoulos, Georgios
contents In this paper we tackle Image Super Resolution (ISR), using recent advances in Visual Auto-Regressive (VAR) modeling. VAR iteratively estimates the residual in latent space between gradually increasing image scales, a process referred to as next-scale prediction. Thus, the strong priors learned during pre-training align well with the downstream task (ISR). To our knowledge, only VARSR has exploited this synergy so far, showing promising results. However, due to the limitations of existing residual quantizers, VARSR works only at a fixed resolution, i.e. it fails to map intermediate outputs to the corresponding image scales. Additionally, it relies on a 1B transformer architecture (VAR-d24), and leverages a large-scale private dataset to achieve state-of-the-art results. We address these limitations through two novel components: a) a Hierarchical Image Tokenization approach with a multi-scale image tokenizer that progressively represents images at different scales while simultaneously enforcing token overlap across scales, and b) a Direct Preference Optimization (DPO) regularization term that, relying solely on the LR and HR tokenizations, encourages the transformer to produce the latter over the former. To the best of our knowledge, this is the first time a quantizer is trained to force semantically consistent residuals at different scales, and the first time that preference-based optimization is used to train a VAR. Using these two components, our model can denoise the LR image and super-resolve at half and full target upscale factors in a single forward pass. Additionally, we achieve \textit{state-of-the-art results on ISR}, while using a small model (300M params vs ~1B params of VARSR), and without using external training data.
format Preprint
id arxiv_https___arxiv_org_abs_2506_04990
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Multi-scale Image Super Resolution with a Single Auto-Regressive Model
Sanchez, Enrique
Hadji, Isma
Bulat, Adrian
Tzelepis, Christos
Martinez, Brais
Tzimiropoulos, Georgios
Computer Vision and Pattern Recognition
In this paper we tackle Image Super Resolution (ISR), using recent advances in Visual Auto-Regressive (VAR) modeling. VAR iteratively estimates the residual in latent space between gradually increasing image scales, a process referred to as next-scale prediction. Thus, the strong priors learned during pre-training align well with the downstream task (ISR). To our knowledge, only VARSR has exploited this synergy so far, showing promising results. However, due to the limitations of existing residual quantizers, VARSR works only at a fixed resolution, i.e. it fails to map intermediate outputs to the corresponding image scales. Additionally, it relies on a 1B transformer architecture (VAR-d24), and leverages a large-scale private dataset to achieve state-of-the-art results. We address these limitations through two novel components: a) a Hierarchical Image Tokenization approach with a multi-scale image tokenizer that progressively represents images at different scales while simultaneously enforcing token overlap across scales, and b) a Direct Preference Optimization (DPO) regularization term that, relying solely on the LR and HR tokenizations, encourages the transformer to produce the latter over the former. To the best of our knowledge, this is the first time a quantizer is trained to force semantically consistent residuals at different scales, and the first time that preference-based optimization is used to train a VAR. Using these two components, our model can denoise the LR image and super-resolve at half and full target upscale factors in a single forward pass. Additionally, we achieve \textit{state-of-the-art results on ISR}, while using a small model (300M params vs ~1B params of VARSR), and without using external training data.
title Multi-scale Image Super Resolution with a Single Auto-Regressive Model
topic Computer Vision and Pattern Recognition
url https://arxiv.org/abs/2506.04990