Retinexformer

 

 

Introduction

This is a baseline and toolbox for low-light image enhancement. This repo supports over 15 benchmarks and extremely high-resolution (up to 4000x6000) low-light enhancement. Our method Retinexformer won the second place in the NTIRE 2024 Challenge on Low Light Enhancement 🏆. Later works based on our Retinexformer won the NTIRE 2025 Low-light Image Enhancement Challenge 🏆 and NTIRE 2026 Efficient Low-light Image Enhancement Challenge 🏆. If you find this repo useful, please give it a star ⭐ and consider citing our paper. Thank you.

Awards

News

• 2026.11.07 : Release our models on HuggingFace 🤗
• 2026.05.23 : The winner solution of NTIRE 2026 Efficient Low-light Image Enhancement Challenge is based on our Retinexformer. Congraduation to them. Feel free to check the challenge report 🏆
• 2025.06.05 : The winner solution of NTIRE 2025 Low-light Image Enhancement Challenge is based on our Retinexformer. Congraduation to them. Feel free to check the challenge report and their challenge paper 🏆
• 2025.02.10 : NTIRE 2025 Low-light Image Enhancement Challenge has started. Welcome to use our Retinexformer and MST to participate in this challenge. 😄
• 2024.09.15 : An enhanced version of Retinexformer (ECCV 2024) has been released at this repo. Feel free to check and use it. 🤗
• 2024.08.07 : We share the code that can draw our teaser figure (the bar comparison) here. Feel free to use it in your research :smile:
• 2024.07.03 : We share more results of compared baseline methods to help your research. Feel free to download them from Google Drive or Baidu Disk :smile:
• 2024.07.01 : An enhanced version of Retinexformer has been accepted by ECCV 2024. Code will be released. Stay tuned. 🚀
• 2024.05.12 : RetinexMamba based on our Retinexformer framework and this repo has been released. The first Mamba work on low-light enhancement. Thanks to the efforts of the authors.
• 2024.03.22 : We release distributed data parallel (DDP) and mix-precision training strategies to help you train larger models. We release self-ensemble testing strategy to help you derive better results. In addition, we also release an adaptive split-and-test testing strategy for high-resolution up to 4000x6000 low-light image enhancement. Feel free to use them. 🚀
• 2024.03.21 : Our methods Retinexformer and MST++ (NTIRE 2022 Spectral Reconstruction Challenge Winner) ranked top-2 in the NTIRE 2024 Challenge on Low Light Enhancement. Code, pre-trained weights, training logs, and enhancement results have been released in this repo. Feel free to use them! 🚀
• 2024.02.15 : NTIRE 2024 Challenge on Low Light Enhancement begins. Welcome to use our Retinexformer or MST++ (NTIRE 2022 Spectral Reconstruction Challenge Winner) to participate in this challenge! :trophy:
• 2023.11.03 : The test setting of KinD, LLFlow, and recent diffusion models and the corresponding results on LOL are provided. Please note that we do not suggest this test setting because it uses the mean of the ground truth to obtain better results. But, if you want to follow KinD, LLFlow, and recent diffusion-based works for fair comparison, it is your choice to use this test setting. Please refer to the Testing part for details.
• 2023.11.02 : Retinexformer is added to the Awesome-Transformer-Attention collection. 💫
• 2023.10.20 : Params and FLOPS evaluating function is provided. Feel free to check and use it.
• 2023.10.12 : Retinexformer is added to the ICCV-2023-paper collection. 🚀
• 2023.10.10 : Retinexformer is added to the low-level-vision-paper-record collection. ⭐
• 2023.10.06 : Retinexformer is added to the awesome-low-light-image-enhancement collection. :tada:
• 2023.09.20 : Some results on ExDark nighttime object detection are released.
• 2023.09.20 : Code, models, results, and training logs have been released. Feel free to use them. ⭐
• 2023.07.14 : Our paper has been accepted by ICCV 2023. Code and Models will be released. :rocket:

Results

• Results on LOL-v1, LOL-v2-real, LOL-v2-synthetic, SID, SMID, SDSD-in, SDSD-out, and MIT Adobe FiveK datasets can be downloaded from Baidu Disk (code: cyh2) or Google Drive

• Results on LOL-v1, LOL-v2-real, and LOL-v2-synthetic datasets with the same test setting as KinD, LLFlow, and recent diffusion models can be downloaded from Baidu Disk (code: cyh2) or Google Drive.

• Results on the NTIRE 2024 low-light enhancement dataset can be downloaded from Baidu Disk (code: cyh2) or Google Drive

• Results on LIME, NPE, MEF, DICM, and VV datasets can be downloaded from Baidu Disk (code: cyh2) or Google Drive

• Results on ExDark nighttime object detection can be downloaded from Baidu Disk (code: cyh2) or Google Drive. Please use this repo to run experiments on the ExDark dataset

• Results of some compared baseline methods are shared on Google Drive and Baidu Disk

Metric	LOL-v1	LOL-v2-real	LOL-v2-synthetic
PSNR	27.18	27.71	29.04
SSIM	0.850	0.856	0.939

Please note that we do not suggest this test setting because it uses the mean of the ground truth to obtain better results. But, if you want to follow KinD, LLFlow, and recent diffusion-based works, it is your choice to use this test setting. Please refer to the Testing part for details.

Method	Retinexformer	MST++	Ensemble
PSNR	24.61	24.59	25.30
SSIM	0.85	0.85	0.85

Feel free to check the Codalab leaderboard. Our method ranks second.

Gallery

NTIRE - dev - 2000x3000	NTIRE - challenge - 4000x6000

 

1. Create Environment

We suggest you use pytorch 1.11 to re-implement the results in our ICCV 2023 paper and pytorch 2 to re-implement the results in NTIRE 2024 Challenge because pytorch 2 can save more memory in mix-precision training.

1.1 Install the environment with Pytorch 1.11

• Make Conda Environment

conda create -n Retinexformer python=3.7
conda activate Retinexformer

• Install Dependencies

conda install pytorch=1.11 torchvision cudatoolkit=11.3 -c pytorch

pip install matplotlib scikit-learn scikit-image opencv-python yacs joblib natsort h5py tqdm tensorboard

pip install einops gdown addict future lmdb numpy pyyaml requests scipy yapf lpips

• Install BasicSR

python setup.py develop --no_cuda_ext

1.2 Install the environment with Pytorch 2

• Make Conda Environment

conda create -n torch2 python=3.9 -y
conda activate torch2

• Install Dependencies

conda install pytorch torchvision torchaudio pytorch-cuda=11.8 -c pytorch -c nvidia

pip install matplotlib scikit-learn scikit-image opencv-python yacs joblib natsort h5py tqdm tensorboard

pip install einops gdown addict future lmdb numpy pyyaml requests scipy yapf lpips thop timm

• Install BasicSR

python setup.py develop --no_cuda_ext

 

2. Prepare Dataset

Download the following datasets:

LOL-v1 Baidu Disk (code: cyh2), Google Drive

LOL-v2 Baidu Disk (code: cyh2), Google Drive

SID Baidu Disk (code: gplv), Google Drive

SMID Baidu Disk (code: btux), Google Drive

SDSD-indoor Baidu Disk (code: jo1v), Google Drive

SDSD-outdoor Baidu Disk (code: uibk), Google Drive

MIT-Adobe FiveK Baidu Disk (code:cyh2), Google Drive, Official

NTIRE 2024 Baidu Disk (code:cyh2), Google Drive links for training input, training GT, and mini-val set.

Note:

(1) Please use bandizip to jointly unzip the .zip and .z01 files of SMID, SDSD-indoor, and SDSD-outdoor

(2) Please process the raw images of the MIT Adobe FiveK dataset following the sRGB output mode or directly download and use the sRGB image pairs processed by us in the Baidu Disk (code:cyh2) and Google Drive

(3) Please download the text_list.txt from Google Drive or Baidu Disk (code: ggbh) and then put it into the folder data/SMID/SMID_Long_np/

    |--data   
    |    |--LOLv1
    |    |    |--Train
    |    |    |    |--input
    |    |    |    |    |--100.png
    |    |    |    |    |--101.png
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--100.png
    |    |    |    |    |--101.png
    |    |    |    |     ...
    |    |    |--Test
    |    |    |    |--input
    |    |    |    |    |--111.png
    |    |    |    |    |--146.png
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--111.png
    |    |    |    |    |--146.png
    |    |    |    |     ...
    |    |--LOLv2
    |    |    |--Real_captured
    |    |    |    |--Train
    |    |    |    |    |--Low
    |    |    |    |    |    |--00001.png
    |    |    |    |    |    |--00002.png
    |    |    |    |    |     ...
    |    |    |    |    |--Normal
    |    |    |    |    |    |--00001.png
    |    |    |    |    |    |--00002.png
    |    |    |    |    |     ...
    |    |    |    |--Test
    |    |    |    |    |--Low
    |    |    |    |    |    |--00690.png
    |    |    |    |    |    |--00691.png
    |    |    |    |    |     ...
    |    |    |    |    |--Normal
    |    |    |    |    |    |--00690.png
    |    |    |    |    |    |--00691.png
    |    |    |    |    |     ...
    |    |    |--Synthetic
    |    |    |    |--Train
    |    |    |    |    |--Low
    |    |    |    |    |   |--r000da54ft.png
    |    |    |    |    |   |--r02e1abe2t.png
    |    |    |    |    |    ...
    |    |    |    |    |--Normal
    |    |    |    |    |   |--r000da54ft.png
    |    |    |    |    |   |--r02e1abe2t.png
    |    |    |    |    |    ...
    |    |    |    |--Test
    |    |    |    |    |--Low
    |    |    |    |    |   |--r00816405t.png
    |    |    |    |    |   |--r02189767t.png
    |    |    |    |    |    ...
    |    |    |    |    |--Normal
    |    |    |    |    |   |--r00816405t.png
    |    |    |    |    |   |--r02189767t.png
    |    |    |    |    |    ...
    |    |--SDSD
    |    |    |--indoor_static_np
    |    |    |    |--input
    |    |    |    |    |--pair1
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |    |--pair2
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |     ...
    |    |    |    |--GT
    |    |    |    |    |--pair1
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |    |--pair2
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |     ...
    |    |    |--outdoor_static_np
    |    |    |    |--input
    |    |    |    |    |--MVI_0898
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |    |--MVI_0918
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |     ...
    |    |    |    |--GT
    |    |    |    |    |--MVI_0898
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |    |--MVI_0918
    |    |    |    |    |   |--0001.npy
    |    |    |    |    |   |--0002.npy
    |    |    |    |    |    ...
    |    |    |    |     ...
    |    |--SID
    |    |    |--short_sid2
    |    |    |    |--00001
    |    |    |    |    |--00001_00_0.04s.npy
    |    |    |    |    |--00001_00_0.1s.npy
    |    |    |    |    |--00001_01_0.04s.npy
    |    |    |    |    |--00001_01_0.1s.npy
    |    |    |    |     ...
    |    |    |    |--00002
    |    |    |    |    |--00002_00_0.04s.npy
    |    |    |    |    |--00002_00_0.1s.npy
    |    |    |    |    |--00002_01_0.04s.npy
    |    |    |    |    |--00002_01_0.1s.npy
    |    |    |    |     ...
    |    |    |     ...
    |    |    |--long_sid2
    |    |    |    |--00001
    |    |    |    |    |--00001_00_0.04s.npy
    |    |    |    |    |--00001_00_0.1s.npy
    |    |    |    |    |--00001_01_0.04s.npy
    |    |    |    |    |--00001_01_0.1s.npy
    |    |    |    |     ...
    |    |    |    |--00002
    |    |    |    |    |--00002_00_0.04s.npy
    |    |    |    |    |--00002_00_0.1s.npy
    |    |    |    |    |--00002_01_0.04s.npy
    |    |    |    |    |--00002_01_0.1s.npy
    |    |    |    |     ...
    |    |    |     ...
    |    |--SMID
    |    |    |--SMID_LQ_np
    |    |    |    |--0001
    |    |    |    |    |--0001.npy
    |    |    |    |    |--0002.npy
    |    |    |    |     ...
    |    |    |    |--0002
    |    |    |    |    |--0001.npy
    |    |    |    |    |--0002.npy
    |    |    |    |     ...
    |    |    |     ...
    |    |    |--SMID_Long_np
    |    |    |    |--text_list.txt
    |    |    |    |--0001
    |    |    |    |    |--0001.npy
    |    |    |    |    |--0002.npy
    |    |    |    |     ...
    |    |    |    |--0002
    |    |    |    |    |--0001.npy
    |    |    |    |    |--0002.npy
    |    |    |    |     ...
    |    |    |     ...
    |    |--FiveK
    |    |    |--train
    |    |    |    |--input
    |    |    |    |    |--a0099-kme_264.jpg
    |    |    |    |    |--a0101-kme_610.jpg
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--a0099-kme_264.jpg
    |    |    |    |    |--a0101-kme_610.jpg
    |    |    |    |     ...
    |    |    |--test
    |    |    |    |--input
    |    |    |    |    |--a4574-DSC_0038.jpg
    |    |    |    |    |--a4576-DSC_0217.jpg
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--a4574-DSC_0038.jpg
    |    |    |    |    |--a4576-DSC_0217.jpg
    |    |    |    |     ...
    |    |--NTIRE
    |    |    |--train
    |    |    |    |--input
    |    |    |    |    |--1.png
    |    |    |    |    |--3.png
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--1.png
    |    |    |    |    |--3.png
    |    |    |    |     ...
    |    |    |--minival
    |    |    |    |--input
    |    |    |    |    |--1.png
    |    |    |    |    |--31.png
    |    |    |    |     ...
    |    |    |    |--target
    |    |    |    |    |--1.png
    |    |    |    |    |--31.png
    |    |    |    |     ...

We also provide download links for LIME, NPE, MEF, DICM, and VV datasets that have no ground truth:

Baidu Disk (code: cyh2) or Google Drive

 

3. Testing

Download our models from Hugging Face directly into pretrained_weights:

pip install -U huggingface_hub
hf download CaiYuanhao/Retinexformer --include "*.pth" --local-dir pretrained_weights

Download our models from Baidu Disk (code: cyh2) or Google Drive. Put them in folder pretrained_weights

# activate the environment
conda activate Retinexformer

# LOL-v1
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v1.yml --weights pretrained_weights/LOL_v1.pth --dataset LOL_v1

# LOL-v2-real
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v2_real.yml --weights pretrained_weights/LOL_v2_real.pth --dataset LOL_v2_real

# LOL-v2-synthetic
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v2_synthetic.yml --weights pretrained_weights/LOL_v2_synthetic.pth --dataset LOL_v2_synthetic

# SID
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_SID.yml --weights pretrained_weights/SID.pth --dataset SID

# SMID
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_SMID.yml --weights pretrained_weights/SMID.pth --dataset SMID

# SDSD-indoor
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_SDSD_indoor.yml --weights pretrained_weights/SDSD_indoor.pth --dataset SDSD_indoor

# SDSD-outdoor
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_SDSD_outdoor.yml --weights pretrained_weights/SDSD_outdoor.pth --dataset SDSD_outdoor

# FiveK
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_FiveK.yml --weights pretrained_weights/FiveK.pth --dataset FiveK

# NTIRE
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_NTIRE.yml --weights pretrained_weights/NTIRE.pth --dataset NTIRE --self_ensemble

# MST_Plus_Plus trained with 4 GPUs on NTIRE 
python3 Enhancement/test_from_dataset.py --opt Options/MST_Plus_Plus_NTIRE_4x1800.yml --weights pretrained_weights/MST_Plus_Plus_4x1800.pth --dataset NTIRE --self_ensemble

# MST_Plus_Plus trained with 8 GPUs on NTIRE 
python3 Enhancement/test_from_dataset.py --opt Options/MST_Plus_Plus_NTIRE_8x1150.yml --weights pretrained_weights/MST_Plus_Plus_8x1150.pth --dataset NTIRE --self_ensemble

• Self-ensemble testing strategy

We add the self-ensemble strategy in the testing code to derive better results. Just add a --self_ensemble action at the end of the above test command to use it.

• The same test setting as LLFlow, KinD, and recent diffusion models

We provide the same test setting as LLFlow, KinD, and recent diffusion models. Please note that we do not suggest this test setting because it uses the mean of ground truth to enhance the output of the model. But if you want to follow this test setting, just add a --GT_mean action at the end of the above test command as

# LOL-v1
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v1.yml --weights pretrained_weights/LOL_v1.pth --dataset LOL_v1 --GT_mean

# LOL-v2-real
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v2_real.yml --weights pretrained_weights/LOL_v2_real.pth --dataset LOL_v2_real --GT_mean

# LOL-v2-synthetic
python3 Enhancement/test_from_dataset.py --opt Options/RetinexFormer_LOL_v2_synthetic.yml --weights pretrained_weights/LOL_v2_synthetic.pth --dataset LOL_v2_synthetic --GT_mean

• Evaluating the Params and FLOPS of models

We have provided a function my_summary() in Enhancement/utils.py, please use this function to evaluate the parameters and computational complexity of the models, especially the Transformers as

from utils import my_summary
my_summary(RetinexFormer(), 256, 256, 3, 1)

 

4. Training

Feel free to check our training logs from Baidu Disk (code: cyh2) or Google Drive

We suggest you use the environment with pytorch 2 to train our model on the NTIRE 2024 dataset and the environment with pytorch 1.11 to train our model on other datasets.

# activate the enviroment
conda activate Retinexformer

# LOL-v1
python3 basicsr/train.py --opt Options/RetinexFormer_LOL_v1.yml

# LOL-v2-real
python3 basicsr/train.py --opt Options/RetinexFormer_LOL_v2_real.yml

# LOL-v2-synthetic
python3 basicsr/train.py --opt Options/RetinexFormer_LOL_v2_synthetic.yml

# SID
python3 basicsr/train.py --opt Options/RetinexFormer_SID.yml

# SMID
python3 basicsr/train.py --opt Options/RetinexFormer_SMID.yml

# SDSD-indoor
python3 basicsr/train.py --opt Options/RetinexFormer_SDSD_indoor.yml

# SDSD-outdoor
python3 basicsr/train.py --opt Options/RetinexFormer_SDSD_outdoor.yml

# FiveK
python3 basicsr/train.py --opt Options/RetinexFormer_FiveK.yml

Train our Retinexformer and MST++ with the distributed data parallel (DDP) strategy of pytorch on the NTIRE 2024 Low-Light Enhancement dataset. Please note that we use the mix-precision strategy in the training process, which is controlled by the bool hyperparameter use_amp in the config file.

# activate the enviroment
conda activate torch2

# Train Retinexformer with 8 GPUs on NTIRE
bash train_multigpu.sh Options/RetinexFormer_NTIRE.yml 0,1,2,3,4,5,6,7 4321

# Train MST++ with 4 GPUs on NTIRE
bash train_multigpu.sh Options/RetinexFormer_NTIRE_4x1800.yml 0,1,2,3,4,5,6,7 4329

# Train MST++ with 8 GPUs on NTIRE
bash train_multigpu.sh Options/MST_Plus_Plus_NTIRE_8x1150.yml 0,1,2,3,4,5,6,7 4343

 

5. Citation

@InProceedings{Cai_2023_ICCV,
    author    = {Cai, Yuanhao and Bian, Hao and Lin, Jing and Wang, Haoqian and Timofte, Radu and Zhang, Yulun},
    title     = {Retinexformer: One-stage Retinex-based Transformer for Low-light Image Enhancement},
    booktitle = {Proceedings of the IEEE/CVF International Conference on Computer Vision (ICCV)},
    month     = {October},
    year      = {2023},
    pages     = {12504-12513}
}

@inproceedings{retinexformer,
  title={Retinexformer: One-stage Retinex-based Transformer for Low-light Image Enhancement},
  author={Yuanhao Cai and Hao Bian and Jing Lin and Haoqian Wang and Radu Timofte and Yulun Zhang},
  booktitle={ICCV},
  year={2023}
}


# MST++
@inproceedings{mst,
  title={Mask-guided Spectral-wise Transformer for Efficient Hyperspectral Image Reconstruction},
  author={Yuanhao Cai and Jing Lin and Xiaowan Hu and Haoqian Wang and Xin Yuan and Yulun Zhang and Radu Timofte and Luc Van Gool},
  booktitle={CVPR},
  year={2022}
}