Diffusion-based Real-World Image Super-Resolution (Real-ISR) achieves impressive perceptual quality but suffers from high computational costs due to iterative sampling. While recent distillation approaches leveraging large-scale Text-to-Image (T2I) priors have enabled one-step generation, they are typically hindered by prohibitive parameter counts and the inherent capability bounds imposed by teacher models. As a lightweight alternative, Consistency Models offer efficient inference but struggle with two critical limitations: the accumulation of consistency drift inherent to transitive training, and a phenomenon we term "Geometric Decoupling" - where the generative trajectory achieves pixel-wise alignment yet fails to preserve structural coherence. To address these challenges, we propose GTASR (Geometric Trajectory Alignment Super-Resolution), a simple yet effective consistency training paradigm for Real-ISR. Specifically, we introduce a Trajectory Alignment (TA) strategy to rectify the tangent vector field via full-path projection, and a Dual-Reference Structural Rectification (DRSR) mechanism to enforce strict structural constraints. Extensive experiments verify that GTASR delivers superior performance over representative baselines while maintaining minimal latency. The code and model will be released at https://github.com/Blazedengcy/GTASR.
Figures & tables
Figure 1: The pipeline of the proposed GTASR. We employ a two-stage training scheme. In Stage I, we train the online model fθ using the standard LCT , augmented by our proposed LTA , where the reference parameters θ− are updated at every step using the stop-gradient online parameters. In Stage II, we address geometric decoupling by introducing a target model fθ′ initialized with the pre-trained weights from Stage I, with its parameters updated via periodic synchronization to ensure temporal alignment. We feed the intermediate states x^t′ and xt′ into fθ′ to obtain the trajectory endpoints ( x0fake and x0real ), which are directly utilized for LDTM while their structure maps extracted via the Sobel operator are utilized for the proposed DRSR objectives ( LStab and LRect ). Finally, the gradients derived from LCT , LDTM , LStab , and LRect are backpropagated to fθ to jointly enhance perceptual realism and structural integrity.
Figure 2: Visual analysis of consistency across timesteps. (Left) Baseline CT suffers from severe trajectory drift and detail loss as t increases, particularly in the eye region. (Right) After introducing TA strategy effectively preserves sharp features even at large time steps.
Figure 3: Visual comparison of different strategies. (a) The baseline LCT fails to model fine details effectively. (b) Integrating LTP with LCT guides the reconstruction direction; however, the metallic grille remains overly blurred and lacks definition. (c) Ours restores intricate mesh textures with superior clarity.
Figure 4: Visualization of Geometric Decoupling. Evaluated on 3,000 ImageNet-Test images, the Baseline (blue) achieves positional convergence (low y-axis error) but fails to maintain structural stability (high x-axis variance). In contrast, GTASR (red) minimizes errors on both metrics, effectively resolving the decoupling.
Datasets
Methods
PSNR ↑
SSIM ↑
LPIPS ↓
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
ImageNet-Test
BSRGAN
24.42
0.6585
0.2585
0.5812
54.70
0.3866
6.08
3.90
0.6078
Real-ESRGAN
24.04
0.6650
0.2540
0.5234
52.54
0.3671
6.07
3.83
0.5545
StableSR-200
20.73
0.4650
0.3927
0.6263
56.85
0.4272
8.32
3.49
0.5818
ResShift-15
24.95
0.6741
0.2377
0.5823
53.11
0.4168
6.90
3.45
0.5877
ResShift-4
25.02
0.6833
0.2074
0.5993
52.10
0.3888
7.33
3.40
0.5679
SinSR-1
24.70
0.6635
0.2187
0.6079
53.53
0.4152
6.29
3.58
0.5950
Table 1: Quantitative comparison on ImageNet-Test and RealSR. The best and second-best results are highlighted in bold and underline .
Figure 5: Visual comparisons of different methods on two synthetic examples of the ImageNet-Test dataset.
Methods
RealLQ250
RealSet65
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
BSRGAN
0.5690
63.51
0.3514
4.54
3.31
0.5386
0.6162
65.58
0.3888
4.58
3.72
0.5809
Real-ESRGAN
0.5435
62.52
0.3565
4.13
3.34
0.5079
0.5990
63.22
0.3893
4.41
3.60
0.5365
StableSR-200
0.4001
48.83
0.2694
5.84
2.46
0.4405
0.4492
48.75
0.3098
5.74
2.91
0.4644
ResShift-15
0.6006
58.92
0.3898
6.29
3.11
0.4939
0.6496
61.16
0.4079
6.16
3.34
0.5397
ResShift-4
0.5835
56.20
0.3480
7.34
2.80
0.4420
0.6274
59.39
0.3621
6.74
3.16
0.4951
Table 2: Quantitative results of models on two real-world datasets. The best and second best results are highlighted in bold and underline .
Figure 6: Visual comparisons of different methods on two examples of real-world datasets. Please zoom in for more details.
Methods
Runtime (s) ↓
LPIPS ↓
MANIQA ↑
CLIPIQA ↑
TOPIQ ↑
StableSR-200
11.21
0.3927
0.4272
0.6263
0.5818
ResShift-15
0.93
0.2377
0.4168
0.5823
0.5877
UPSR-5
0.35
0.2464
0.4695
0.6149
0.6491
SinSR-1
0.12
0.2187
0.4152
0.6079
0.5950
CTMSR-1
0.08
0.1969
0.4857
0.6912
0.6793
GTASR-1 (Ours)
0.08
0.1916
0.5826
0.7475
0.7423
Table 3: Computational efficiency and performance comparison. We report Runtime for 128×128 input on a single RTX 4090 GPU and present perceptual metrics evaluated on ImageNet-Test.
Method
PSNR ↑
LPIPS ↓
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
LIQE ↑
TOPIQ ↑
w/o LTA
24.65
0.2073
0.6060
55.38
0.3830
3.86
0.5939
w/ LTA
25.05
0.1856
0.6291
58.40
0.4457
4.05
0.6433
Table 4: Ablation study of the Stage-I training objectives on ImageNet-Test.
LDTM
LStab
LRect
PSNR ↑
LPIPS ↓
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
LIQE ↑
TOPIQ ↑
✓
24.76
0.2019
0.6965
58.91
0.5070
3.77
0.6863
✓
✓
24.00
0.1929
0.7351
63.43
0.5676
4.42
0.7349
✓
✓
24.62
0.2000
0.7040
60.41
0.5403
3.89
0.6953
✓
✓
✓
24.01
0.1916
0.7475
65.09
0.5826
4.47
0.7423
Table 5: Ablation study of the Stage-II training objectives on ImageNet-Test.
Appendix figures & tables11 assets
Supplementary material from the paper’s appendix.
Appendix
Methods
Runtime (s) ↓
Params (M) ↓
LPIPS ↓
MUSIQ ↑
MANIQA ↑
CLIPIQA ↑
LIQE ↑
TOPIQ ↑
StableSR-200
11.21
1928
0.3927
56.85
0.4272
0.6263
3.49
0.5818
ResShift-15
0.93
174
0.2377
53.11
0.4168
0.5823
3.45
0.5877
ResShift-4
0.37
174
0.2074
52.10
0.3888
0.5993
3.40
0.5679
UPSR-5
0.35
122
0.2464
59.20
0.4695
0.6149
4.00
0.6491
SinSR-1
0.12
174
0.2187
53.53
0.4152
0.6079
3.58
0.5950
CTMSR-1
0.08
172
0.1969
60.17
0.4857
0.6912
4.08
0.6793
Appendix
Table 6: Computational efficiency and performance comparison. We report Runtime and Parameters (Params) measured with an input size of 128×128 on a single RTX 4090 GPU. We also present perceptual metrics evaluated on ImageNet-Test . Bold and underlined indicate the best and second-best performance, respectively.
Methods
Runtime (s) ↓
Params (M) ↓
PSNR ↑
SSIM ↑
LPIPS ↓
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
AddSR-4
0.70
2280
24.23
0.7032
0.3141
0.5127
62.64
0.4116
6.19
3.38
0.5535
OSEDiff-1
0.43
1775
25.15
0.7341
0.2921
0.6682
69.08
0.4717
5.64
4.06
0.6253
GTASR-1 (Ours)
0.08
172
25.92
0.7471
0.3041
0.6962
67.31
0.4930
5.33
3.70
0.6780
Appendix
Table 7: Quantitative comparison on RealSR with center-cropped 128×128 LR inputs. The best and second-best results are highlighted in bold and underline (”-N” behind the method name represents the number of inference steps).
Methods
RealLQ250
RealSet65
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
AddSR-4
0.5732
64.40
0.3681
4.44
3.26
0.5486
0.5917
63.77
0.3903
5.22
3.49
0.5586
OSEDiff-1
0.6722
69.556
0.4250
3.98
3.90
0.6075
0.7041
68.65
0.4699
4.79
4.08
0.6137
GTASR-1 (Ours)
0.7355
70.90
0.4870
4.32
3.79
0.7047
0.7491
69.49
0.4989
4.45
3.97
0.6937
Appendix
Table 8: Quantitative results of models on two real-world datasets. The best and second best results are highlighted in bold and underline .
LCT
LTA
LDTM
LStab
LRect
PSNR ↑
SSIM ↑
LPIPS ↓
CLIPIQA ↑
MUSIQ ↑
MANIQA ↑
NIQE ↓
LIQE ↑
TOPIQ ↑
✓
✓
✓
✓
24.24
0.6540
0.2040
0.7036
61.94
0.4770
5.87
4.20
0.7036
✓
✓
✓
✓
✓
24.01
0.6520
0.1916
0.7475
65.09
0.5826
5.83
4.47
0.7423
Appendix
Table 9: Impact of the Trajectory Alignment (TA) strategy on restoration quality on ImageNet-Test. The best and second best results are highlighted in bold and underline .
Figure 7: Visual comparison of different methods on a synthetic dataset. Please zoom in for more details.
Figure 8: Visual comparison of different methods on a synthetic dataset. Please zoom in for more details.
Figure 9: Visual comparison of different methods on a synthetic dataset. Please zoom in for more details.
Figure 10: Visual comparison of different methods on a synthetic dataset. Please zoom in for more details.
Figure 11: Visual comparison of different methods on real-world datasets. Please zoom in for more details.
Figure 12: Visual comparison of different methods on real-world datasets. Please zoom in for more details.
Figure 13: Visual comparison of different methods on real-world datasets. Please zoom in for more details.