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StyleGAN2 — Official TensorFlow Implementation

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Analyzing and Improving the Image Quality of StyleGAN
Tero Karras, Samuli Laine, Miika Aittala, Janne Hellsten, Jaakko Lehtinen, Timo Aila


Abstract: The style-based GAN architecture (StyleGAN) yields state-of-the-art results in data-driven unconditional generative image modeling. We expose and analyze several of its characteristic artifacts, and propose changes in both model architecture and training methods to address them. In particular, we redesign generator normalization, revisit progressive growing, and regularize the generator to encourage good conditioning in the mapping from latent vectors to images. In addition to improving image quality, this path length regularizer yields the additional benefit that the generator becomes significantly easier to invert. This makes it possible to reliably detect if an image is generated by a particular network. We furthermore visualize how well the generator utilizes its output resolution, and identify a capacity problem, motivating us to train larger models for additional quality improvements. Overall, our improved model redefines the state of the art in unconditional image modeling, both in terms of existing distribution quality metrics as well as perceived image quality.

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Additional material  
StyleGAN2 Main Google Drive folder
├  stylegan2-paper.pdf High-quality version of the paper
├  stylegan2-video.mp4 High-quality version of the video
├  images Example images produced using our method
│  ├  curated-images Hand-picked images showcasing our results
│  └  100k-generated-images Random images with and without truncation
├  videos Individual clips of the video as high-quality MP4
└  networks Pre-trained networks
   ├  stylegan2-ffhq-config-f.pkl StyleGAN2 for FFHQ dataset at 1024×1024
   ├  stylegan2-car-config-f.pkl StyleGAN2 for LSUN Car dataset at 512×384
   ├  stylegan2-cat-config-f.pkl StyleGAN2 for LSUN Cat dataset at 256×256
   ├  stylegan2-church-config-f.pkl StyleGAN2 for LSUN Church dataset at 256×256
   ├  stylegan2-horse-config-f.pkl StyleGAN2 for LSUN Horse dataset at 256×256
   └ ⋯ Other training configurations used in the paper


  • Both Linux and Windows are supported. Linux is recommended for performance and compatibility reasons.
  • 64-bit Python 3.6 installation. We recommend Anaconda3 with numpy 1.14.3 or newer.
  • We recommend TensorFlow 1.14, which we used for all experiments in the paper, but TensorFlow 1.15 is also supported on Linux. TensorFlow 2.x is not supported.
  • On Windows you need to use TensorFlow 1.14, as the standard 1.15 installation does not include necessary C++ headers.
  • One or more high-end NVIDIA GPUs, NVIDIA drivers, CUDA 10.0 toolkit and cuDNN 7.5. To reproduce the results reported in the paper, you need an NVIDIA GPU with at least 16 GB of DRAM.
  • Docker users: use the provided Dockerfile to build an image with the required library dependencies.

StyleGAN2 relies on custom TensorFlow ops that are compiled on the fly using NVCC. To test that your NVCC installation is working correctly, run:

nvcc -o test_nvcc -run
| CPU says hello.
| GPU says hello.

On Windows, the compilation requires Microsoft Visual Studio to be in PATH. We recommend installing Visual Studio Community Edition and adding into PATH using "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Auxiliary\Build\vcvars64.bat".

Using pre-trained networks

Pre-trained networks are stored as *.pkl files on the StyleGAN2 Google Drive folder. Below, you can either reference them directly using the syntax gdrive:networks/<filename>.pkl, or download them manually and reference by filename.

# Generate uncurated ffhq images (matches paper Figure 12)
python generate-images --network=gdrive:networks/stylegan2-ffhq-config-f.pkl \
  --seeds=6600-6625 --truncation-psi=0.5

# Generate curated ffhq images (matches paper Figure 11)
python generate-images --network=gdrive:networks/stylegan2-ffhq-config-f.pkl \
  --seeds=66,230,389,1518 --truncation-psi=1.0

# Generate uncurated car images
python generate-images --network=gdrive:networks/stylegan2-car-config-f.pkl \
  --seeds=6000-6025 --truncation-psi=0.5

# Example of style mixing (matches the corresponding video clip)
python style-mixing-example --network=gdrive:networks/stylegan2-ffhq-config-f.pkl \
  --row-seeds=85,100,75,458,1500 --col-seeds=55,821,1789,293 --truncation-psi=1.0

The results are placed in results/<RUNNING_ID>/*.png. You can change the location with --result-dir. For example, --result-dir=~/my-stylegan2-results.

You can import the networks in your own Python code using pickle.load(). For this to work, you need to include the dnnlib source directory in PYTHONPATH and create a default TensorFlow session by calling dnnlib.tflib.init_tf(). See and for examples.

Preparing datasets

Datasets are stored as multi-resolution TFRecords, similar to the original StyleGAN. Each dataset consists of multiple *.tfrecords files stored under a common directory, e.g., ~/datasets/ffhq/ffhq-r*.tfrecords. In the following sections, the datasets are referenced using a combination of --dataset and --data-dir arguments, e.g., --dataset=ffhq --data-dir=~/datasets.

FFHQ. To download the Flickr-Faces-HQ dataset as multi-resolution TFRecords, run:

pushd ~
git clone
cd ffhq-dataset
python --tfrecords
python display ~/ffhq-dataset/tfrecords/ffhq

LSUN. Download the desired LSUN categories in LMDB format from the LSUN project page. To convert the data to multi-resolution TFRecords, run:

python create_lsun_wide ~/datasets/car ~/lsun/car_lmdb --width=512 --height=384
python create_lsun ~/datasets/cat ~/lsun/cat_lmdb --resolution=256
python create_lsun ~/datasets/church ~/lsun/church_outdoor_train_lmdb --resolution=256
python create_lsun ~/datasets/horse ~/lsun/horse_lmdb --resolution=256

Custom. Create custom datasets by placing all training images under a single directory. The images must be square-shaped and they must all have the same power-of-two dimensions. To convert the images to multi-resolution TFRecords, run:

python create_from_images ~/datasets/my-custom-dataset ~/my-custom-images
python display ~/datasets/my-custom-dataset

Projecting images to latent space

To find the matching latent vectors for a set of images, run:

# Project generated images
python project-generated-images --network=gdrive:networks/stylegan2-car-config-f.pkl \

# Project real images
python project-real-images --network=gdrive:networks/stylegan2-car-config-f.pkl \
  --dataset=car --data-dir=~/datasets

Training networks

To reproduce the training runs for config F in Tables 1 and 3, run:

python --num-gpus=8 --data-dir=~/datasets --config=config-f \
  --dataset=ffhq --mirror-augment=true
python --num-gpus=8 --data-dir=~/datasets --config=config-f \
  --dataset=car --total-kimg=57000
python --num-gpus=8 --data-dir=~/datasets --config=config-f \
  --dataset=cat --total-kimg=88000
python --num-gpus=8 --data-dir=~/datasets --config=config-f \
  --dataset=church --total-kimg 88000 --gamma=100
python --num-gpus=8 --data-dir=~/datasets --config=config-f \
  --dataset=horse --total-kimg 100000 --gamma=100

For other configurations, see python --help.

We have verified that the results match the paper when training with 1, 2, 4, or 8 GPUs. Note that training FFHQ at 1024×1024 resolution requires GPU(s) with at least 16 GB of memory. The following table lists typical training times using NVIDIA DGX-1 with 8 Tesla V100 GPUs:

Configuration Resolution Total kimg 1 GPU 2 GPUs 4 GPUs 8 GPUs GPU mem
config-f 1024×1024 25000 69d 23h 36d 4h 18d 14h 9d 18h 13.3 GB
config-f 1024×1024 10000 27d 23h 14d 11h 7d 10h 3d 22h 13.3 GB
config-e 1024×1024 25000 35d 11h 18d 15h 9d 15h 5d 6h 8.6 GB
config-e 1024×1024 10000 14d 4h 7d 11h 3d 20h 2d 3h 8.6 GB
config-f 256×256 25000 32d 13h 16d 23h 8d 21h 4d 18h 6.4 GB
config-f 256×256 10000 13d 0h 6d 19h 3d 13h 1d 22h 6.4 GB

Training curves for FFHQ config F (StyleGAN2) compared to original StyleGAN using 8 GPUs:

Training curves

After training, the resulting networks can be used the same way as the official pre-trained networks:

# Generate 1000 random images without truncation
python generate-images --seeds=0-999 --truncation-psi=1.0 \

Evaluation metrics

To reproduce the numbers for config F in Tables 1 and 3, run:

python --data-dir=~/datasets --network=gdrive:networks/stylegan2-ffhq-config-f.pkl \
  --metrics=fid50k,ppl_wend --dataset=ffhq --mirror-augment=true
python --data-dir=~/datasets --network=gdrive:networks/stylegan2-car-config-f.pkl \
  --metrics=fid50k,ppl2_wend --dataset=car
python --data-dir=~/datasets --network=gdrive:networks/stylegan2-cat-config-f.pkl \
  --metrics=fid50k,ppl2_wend --dataset=cat
python --data-dir=~/datasets --network=gdrive:networks/stylegan2-church-config-f.pkl \
  --metrics=fid50k,ppl2_wend --dataset=church
python --data-dir=~/datasets --network=gdrive:networks/stylegan2-horse-config-f.pkl \
  --metrics=fid50k,ppl2_wend --dataset=horse

For other configurations, see the StyleGAN2 Google Drive folder.

Note that the metrics are evaluated using a different random seed each time, so the results will vary between runs. In the paper, we reported the average result of running each metric 10 times. The following table lists the available metrics along with their expected runtimes and random variation:

Metric FFHQ config F 1 GPU 2 GPUs 4 GPUs Description
fid50k 2.84 ± 0.03 22 min 14 min 10 min Fréchet Inception Distance
is50k 5.13 ± 0.02 23 min 14 min 8 min Inception Score
ppl_zfull 348.0 ± 3.8 41 min 22 min 14 min Perceptual Path Length in Z, full paths
ppl_wfull 126.9 ± 0.2 42 min 22 min 13 min Perceptual Path Length in W, full paths
ppl_zend 348.6 ± 3.0 41 min 22 min 14 min Perceptual Path Length in Z, path endpoints
ppl_wend 129.4 ± 0.8 40 min 23 min 13 min Perceptual Path Length in W, path endpoints
ppl2_wend 145.0 ± 0.5 41 min 23 min 14 min Perceptual Path Length without center crop
ls 154.2 / 4.27 10 hrs 6 hrs 4 hrs Linear Separability
pr50k3 0.689 / 0.492 26 min 17 min 12 min Precision and Recall

Note that some of the metrics cache dataset-specific data on the disk, and they will take somewhat longer when run for the first time.


Copyright © 2019, NVIDIA Corporation. All rights reserved.

This work is made available under the Nvidia Source Code License-NC. To view a copy of this license, visit


  title     = {Analyzing and Improving the Image Quality of {StyleGAN}},
  author    = {Tero Karras and Samuli Laine and Miika Aittala and Janne Hellsten and Jaakko Lehtinen and Timo Aila},
  booktitle = {Proc. CVPR},
  year      = {2020}


We thank Ming-Yu Liu for an early review, Timo Viitanen for his help with code release, and Tero Kuosmanen for compute infrastructure.


StyleGAN2 - Official TensorFlow Implementation







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