CycleGAN and pix2pix in PyTorch

Udpate in 2025: we recently updated the code to support Python 3.11 and PyTorch 2.4. It also supports DDP for single-machine multiple-GPU training. (Please use torchrun --nproc_per_node=4 train.py ...)

New: Please check out img2img-turbo repo that includes both pix2pix-turbo and CycleGAN-Turbo. Our new one-step image-to-image translation methods can support both paired and unpaired training and produce better results by leveraging the pre-trained StableDiffusion-Turbo model. The inference time for 512x512 image is 0.29 sec on A6000 and 0.11 sec on A100.

Please check out contrastive-unpaired-translation (CUT), our new unpaired image-to-image translation model that enables fast and memory-efficient training.

We provide PyTorch implementations for both unpaired and paired image-to-image translation.

The code was written by Jun-Yan Zhu and Taesung Park, and supported by Tongzhou Wang.

This PyTorch implementation produces results comparable to or better than our original Torch software. If you would like to reproduce the same results as in the papers, check out the original CycleGAN Torch and pix2pix Torch code in Lua/Torch.

Note: The current software works well with PyTorch 2.4+. Check out the older branch that supports PyTorch 0.1-0.3.

You may find useful information in training/test tips and frequently asked questions. To implement custom models and datasets, check out our templates. To help users better understand and adapt our codebase, we provide an overview of the code structure of this repository.

CycleGAN: Project | Paper | Torch | Tensorflow Core Tutorial | PyTorch Colab

Pix2pix: Project | Paper | Torch | Tensorflow Core Tutorial | PyTorch Colab

EdgesCats Demo | pix2pix-tensorflow | by Christopher Hesse

If you use this code for your research, please cite:

Unpaired Image-to-Image Translation using Cycle-Consistent Adversarial Networks.

Jun-Yan Zhu*, Taesung Park*, Phillip Isola, Alexei A. Efros. In ICCV 2017. (* equal contributions) [Bibtex]

Image-to-Image Translation with Conditional Adversarial Networks.

Phillip Isola, Jun-Yan Zhu, Tinghui Zhou, Alexei A. Efros. In CVPR 2017. [Bibtex]

Talks and Course

pix2pix slides: keynote | pdf, CycleGAN slides: pptx | pdf

CycleGAN course assignment code and handout designed by Prof. Roger Grosse for CSC321 "Intro to Neural Networks and Machine Learning" at University of Toronto. Please contact the instructor if you would like to adopt it in your course.

Colab Notebook

TensorFlow Core CycleGAN Tutorial: Google Colab | Code

TensorFlow Core pix2pix Tutorial: Google Colab | Code

PyTorch Colab notebook: CycleGAN and pix2pix

ZeroCostDL4Mic Colab notebook: CycleGAN and pix2pix

Other implementations

CycleGAN

[Tensorflow] (by Harry Yang), [Tensorflow] (by Archit Rathore), [Tensorflow] (by Van Huy), [Tensorflow] (by Xiaowei Hu), [Tensorflow2] (by Zhenliang He), [TensorLayer1.0] (by luoxier), [TensorLayer2.0] (by zsdonghao), [Chainer] (by Yanghua Jin), [Minimal PyTorch] (by yunjey), [Mxnet] (by Ldpe2G), [lasagne/Keras] (by tjwei), [Keras] (by Simon Karlsson), [OneFlow] (by Ldpe2G)

pix2pix

[Tensorflow] (by Christopher Hesse), [Tensorflow] (by Eyyüb Sariu), [Tensorflow (face2face)] (by Dat Tran), [Tensorflow (film)] (by Arthur Juliani), [Tensorflow (zi2zi)] (by Yuchen Tian), [Chainer] (by mattya), [tf/torch/keras/lasagne] (by tjwei), [Pytorch] (by taey16)

Prerequisites

• Linux or macOS
• Python 3
• CPU or NVIDIA GPU + CUDA CuDNN

Getting Started

Installation

• Clone this repo:

git clone https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix
cd pytorch-CycleGAN-and-pix2pix

• Install PyTorch and other dependencies. For Conda users, you can create a new Conda environment by

conda env create -f environment.yml

and then activate the environment by

conda activate pytorch-img2img

• For Docker users, we provide the pre-built Docker image and Dockerfile. Please refer to our Docker page.
• For Repl users, please click .

CycleGAN train/test

• Download a CycleGAN dataset (e.g. maps):

bash ./datasets/download_cyclegan_dataset.sh maps

• To log training progress and test images to W&B dashboard, set the --use_wandb flag with training script
• Train a model:

#!./scripts/train_cyclegan.sh
python train.py --dataroot ./datasets/maps --name maps_cyclegan --model cycle_gan --use_wandb

To see more intermediate results, check out ./checkpoints/maps_cyclegan/web/index.html.

• Test the model:

#!./scripts/test_cyclegan.sh
python test.py --dataroot ./datasets/maps --name maps_cyclegan --model cycle_gan

• The test results will be saved to a html file here: ./results/maps_cyclegan/latest_test/index.html.

pix2pix train/test

• Download a pix2pix dataset (e.g.facades):

bash ./datasets/download_pix2pix_dataset.sh facades

• To log training progress and test images to W&B dashboard, set the --use_wandb flag with training script
• Train a model:

#!./scripts/train_pix2pix.sh
python train.py --dataroot ./datasets/facades --name facades_pix2pix --model pix2pix --direction BtoA  --use_wandb

To see more intermediate results, check out ./checkpoints/facades_pix2pix/web/index.html.

• Test the model (bash ./scripts/test_pix2pix.sh):

#!./scripts/test_pix2pix.sh
python test.py --dataroot ./datasets/facades --name facades_pix2pix --model pix2pix --direction BtoA

• The test results will be saved to a html file here: ./results/facades_pix2pix/test_latest/index.html. You can find more scripts at scripts directory.
• To train and test pix2pix-based colorization models, please add --model colorization and --dataset_mode colorization. See our training tips for more details.

Apply a pre-trained model (CycleGAN)

• You can download a pretrained model (e.g. horse2zebra) with the following script:

bash ./scripts/download_cyclegan_model.sh horse2zebra

• The pretrained model is saved at ./checkpoints/{name}_pretrained/latest_net_G.pth. Check here for all the available CycleGAN models.
• To test the model, you also need to download the horse2zebra dataset:

bash ./datasets/download_cyclegan_dataset.sh horse2zebra

• Then generate the results using

python test.py --dataroot datasets/horse2zebra/testA --name horse2zebra_pretrained --model test --no_dropout

• The option --model test is used for generating results of CycleGAN only for one side. This option will automatically set --dataset_mode single, which only loads the images from one set. On the contrary, using --model cycle_gan requires loading and generating results in both directions, which is sometimes unnecessary. The results will be saved at ./results/. Use --results_dir {directory_path_to_save_result} to specify the results directory.

• For pix2pix and your own models, you need to explicitly specify --netG, --norm, --no_dropout to match the generator architecture of the trained model. See this FAQ for more details.

Apply a pre-trained model (pix2pix)

Download a pre-trained model with ./scripts/download_pix2pix_model.sh.

• Check here for all the available pix2pix models. For example, if you would like to download label2photo model on the Facades dataset,

bash ./scripts/download_pix2pix_model.sh facades_label2photo

• Download the pix2pix facades datasets:

bash ./datasets/download_pix2pix_dataset.sh facades

• Then generate the results using

python test.py --dataroot ./datasets/facades/ --direction BtoA --model pix2pix --name facades_label2photo_pretrained

• Note that we specified --direction BtoA as Facades dataset's A to B direction is photos to labels.

• If you would like to apply a pre-trained model to a collection of input images (rather than image pairs), please use --model test option. See ./scripts/test_single.sh for how to apply a model to Facade label maps (stored in the directory facades/testB).

• See a list of currently available models at ./scripts/download_pix2pix_model.sh

Multi-GPU training

To train a model on multiple GPUs, please use torchrun --nproc_per_node=4 train.py ... instead of python train.py .... We also need to use synchronized batchnorm by setting --norm sync_batch (or --norm sync_instance for instance normgalization). The --norm batch is not compatible with DDP.

Docker

We provide the pre-built Docker image and Dockerfile that can run this code repo. See docker.

Datasets

Download pix2pix/CycleGAN