Research map / Image generation / Super-resolution
NSARM: Next-Scale Autoregressive Modeling for Robust Real-World Image Super-Resolution
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Proposes NSARM, a pure autoregressive Real-ISR model that builds on the pre-trained 8B Infinity bitwise next-scale model by replacing its first seven scales with a transformation network's output from the LR image, trained in two stages, to improve robustness and speed.
Problem
Real-world image super-resolution with diffusion-based methods suffers from over-enhancement, hallucinations, and failure cases across varying inputs, while existing AR Real-ISR methods are slow or limited by discrete codebooks.
Approach
Use the LR image to directly generate the preliminary coarse scales of a bitwise next-scale AR model (via a lightweight transformation network), then fully fine-tune the whole Infinity model with its original bitwise cross-entropy objective, so the generation pathway starts from the LR content.
Key results
- On RP60 at 512x512, NSARM achieves the best CLIPIQA (0.8564), MUSIQ (73.95) and TOPIQ (0.7615) averages among compared methods, with lowest TOPIQ variance (0.0021).
- NSARM reports 1.2 s inference at 1024x1024 versus 11.7-13 s for SUPIR and SeeSR, and 380 s for PURE at 512x512; total parameters are 8,760M, the largest in the comparison.
- In a 12-participant user study, NSARM received 55.6% of first-choice votes (267 of 480), with VARSR second at 14%.
Surprising findings
- On full-reference metrics NSARM trails SD-based methods substantially on DRealSR and RealSR (e.g., PSNR 26.66 vs 28.88 for PiSA-SR on DRealSR), attributed to bitwise quantization reducing pixel fidelity.
- Prompt choice has only marginal effect on NSARM; a fixed generic prompt performs nearly as well as LLaVA-generated captions.
Limitations
- Bitwise generation reduces pixel-level fidelity compared with continuous-space methods, with weaker PSNR/SSIM/LPIPS.
- Fixed output size of 1024x1024 from the base Infinity model; patch-based inference or resizing needed for other sizes.
- Very large parameter count (8.76B) with no speed or size advantage over lightweight methods.
Experimental setup
Datasets: Unsplash (1M images) DIV2K Validation (100 crops, test) RealSR DRealSR RP60
Benchmarks: DIV2K DRealSR RealSR RP60
Metrics: PSNR SSIM LPIPS NIQE MANIQA MUSIQ CLIPIQA TOPIQ variance Deficient/Poor/Collapse failure counts
Baselines: SeeSR SUPIR OSEDiff PiSA-SR PURE VARSR
Builds on: Infinity VAR VARSR PURE binary spherical quantization
Closest papers by meaning
- Visual Autoregressive Modeling for Image Super-Resolution (ICML 2025 · similarity 0.91)
- Noise-Started One-Step Image Super-Resolution via LR-Conditioned SplitMeanFlow and GAN Refinement (NeurIPS 2026 · similarity 0.90)
- Visual Autoregressive Modeling: Scalable Image Generation via Next-Scale Prediction (NeurIPS 2024 · similarity 0.89)
- TSD-SR: One-Step Diffusion with Target Score Distillation for Real-World Image Super-Resolution (CVPR 2025 · similarity 0.89)
- HMAR: Efficient Hierarchical Masked Auto-Regressive Image Generation (CVPR 2025 · similarity 0.89)
- SinSR: Diffusion-Based Image Super-Resolution in a Single Step (CVPR 2024 · similarity 0.89)
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