This repository is for MSNLN introduced in the following paper

Sowon Kim, Hanhoon Park*, "Image super-resolution using multi-scale non-local attention", Journal of Electronic Imaging 32(1), 013043 (24 February 2023), [Paper]

The code is built on EDSR (PyTorch) and CSNLN, tested on window 10 environment (Python3.6.5, PyTorch_1.7.1) with GeForce RTX 2080 Ti GPU.

1. Introduction
2. Train
3. Test
4. Results
5. Citation
6. Acknowledgements

Since the deep learning-based methods were proposed, compared with traditional methods, they use large-scale external image priors for SISR. However, still most existing deep convoultion-based SISR works have ignored the long-range feature-wise similarities in natural images. Cross-Scale Non-Local Network (CSNLN) overcomes these problems by capturing recurring small patches in different scale and achieved considerable performance gain. Inspired by CSNLN, we proposed Multi-Scale Non-Local Netowrk (MSNLN). MSNLN adopts the benefits of CSNLN but unlike CSNLN, it is made to capture similarities within the same size of small patches. Experimental results demonstrate that proposed MSNLN shows superior performance over prior CSNLN by multiple SISR benchmarks.

The proposed MSNLN architecture. SEM structure in CSNLN, it fuses features learned from a Cross-Scale Non-Local (CS-NL) attention, with others from In-Scale Non-Local (IS-NL) and the local paths. SEM structure in MSNLN, it fuses features learned from a proposed Multi-Scale Non-Local (MS-NL) attention and the local paths.

1. Download DIV2K training data (800 training + 100 validtion images) from DIV2K dataset or SNU_CVLab.

2. Specify '--dir_data' based on the HR and LR images path.

Code is based on EDSR and CSNLN. For more information, please refer to EDSR(PyTorch) or CSNLN.

```
# Example X2 SR
python3 main.py --chop --batch_size 4 --model MSNLN_631_3 --scale 2 --patch_size 64 --save MSNLN_631_3_x2 --n_feats 128 --depth 12 --data_train DIV2K --save_models
```

Pre-traind models can be downloaded from ...

```
# No self-ensemble: MSNLN
# Example X2 SR
python3 main.py --model MSNLN_631_3 --data_test Set5+Set14+B100+Urban100 --data_range 801-900 --scale 2 --n_feats 128 --depth 12 --pre_train ./experiment/MSNLN_631_3_x2/model/model_best.pt --save_results --test_only --chop
```

Here we provide demo test samples. Since Set5 dataset is consisted of 5 images, we randomly extracted 10 images from B100, Detroit, Manga109. You can check that demo datasets PSNR average is over 37dB.

```
# No self-ensemble: MSNLN
# Example X2 SR
# Sample test datasets: Set5, B100, Manga109, Detroit
python3 main.py --model MSNLN_631_3 --data_test Set5+B100+Detroit+Manga109 --data_range 801-900 --scale 2 --n_feats 128 --depth 12 --pre_train ./experiment/MSNLN_631_3_x2/model/model_best.pt --save_results --test_only --chop
```

Making model...
Loading model from ./experiment/MSNLN_631_3_x2/model/model_best.pt
Total params: 3.68M

Evaluation:
100%|█████████████████████████████████████████████| 5/5 [00:47<00:00, 10.11s/it]
[Set5 x2] PSNR: 37.248 (Best: 37.248 @epoch 1)
Forward: 47.14s
100%|███████████████████████████████████████████| 10/10 [02:17<00:00, 13.71s/it]
[B100 x2] PSNR: 35.923 (Best: 35.923 @epoch 1)
Forward: 137.43s
100%|███████████████████████████████████████████| 10/10 [15:42<00:00, 94.19s/it]
[Manga109 x2] PSNR: 39.715 (Best: 39.715 @epoch 1)
Forward: 942.34s
100%|███████████████████████████████████████████| 10/10 [03:49<00:00, 22.85s/it]
[Detroit x2] PSNR: 41.345 (Best: 41.345 @epoch 1)
Forward: 229.33s

If you find the code helpful in your resarch or work, please cite the following papers.

@article{kim2023image,
  title={Image super-resolution using multi-scale non-local attention},
  author={Kim, Sowon and Park, Hanhoon},
  journal={Journal of Electronic Imaging},
  volume={32},
  number={1},
  pages={013043},
  year={2023},
  publisher={SPIE}
}

This code is built on EDSR (PyTorch) and CSNLN. We thank the authors for sharing their codes.