Progressive Growing of GANs for Improved Quality, Stability, and Variation
Tero Karras (NVIDIA), Timo Aila (NVIDIA), Samuli Laine (NVIDIA), Jaakko Lehtinen (NVIDIA and Aalto University)
Picture: Two imaginary celebrities that were dreamed up by a random number generator.
We describe a new training methodology for generative adversarial networks. The key idea is to grow both the generator and discriminator progressively: starting from a low resolution, we add new layers that model increasingly fine details as training progresses. This both speeds the training up and greatly stabilizes it, allowing us to produce images of unprecedented quality, e.g., CelebA images at 1024². We also propose a simple way to increase the variation in generated images, and achieve a record inception score of 8.80 in unsupervised CIFAR10. Additionally, we describe several implementation details that are important for discouraging unhealthy competition between the generator and discriminator. Finally, we suggest a new metric for evaluating GAN results, both in terms of image quality and variation. As an additional contribution, we construct a higher-quality version of the CelebA dataset.
All the material, including source code, is made freely available for non-commercial use under the Creative Commons CC BY-NC 4.0 license. Feel free to use any of the material in your own work, as long as you give us appropriate credit by mentioning the title and author list of our paper.
There are two different versions of the source code. The TensorFlow version is newer and more polished, and we generally recommend it as a starting point if you are looking to experiment with our technique, build upon it, or apply it to novel datasets. The original Theano version, on the other hand, is what we used to produce all the results shown in our paper. We recommend using it if – and only if – you are looking to reproduce our exact results for benchmark datasets like CIFAR-10, MNIST-RGB, and CelebA.
The main differences are summarized in the following table:
| Feature | TensorFlow version | Original Theano version |
| :-------------------------------- | :-------------------------------------------: | :-----------------------: |
| Branch | master (this branch) | original-theano-version |
| Multi-GPU support | Yes | No |
| FP16 mixed-precision support | Yes | No |
| Performance | High | Low |
| Training time for CelebA-HQ | 2 days (8 GPUs)
2 weeks (1 GPU) | 1–2 months | | Repro CelebA-HQ results | Yes – very close | Yes – identical | | Repro LSUN results | Yes – very close | Yes – identical | | Repro CIFAR-10 results | No | Yes – identical | | Repro MNIST mode recovery | No | Yes – identical | | Repro ablation study (Table 1) | No | Yes – identical | | Dataset format | TFRecords | HDF5 | | Backwards compatibility | Can import networks
trained with Theano | N/A | | Code quality | Reasonable | Somewhat messy | | Code status | In active use | No longer maintained |
All pre-trained networks found on Google Drive, as well as ones produced by the training script, are stored as Python PKL files. They can be imported using the standard
picklemechanism as long as two conditions are met: (1) The directory containing the Progressive GAN code repository must be included in the PYTHONPATH environment variable, and (2) a
tf.Session()object must have been created beforehand and set as default. Each PKL file contains 3 instances of
# Import official CelebA-HQ networks. with open('karras2018iclr-celebahq-1024x1024.pkl', 'rb') as file: G, D, Gs = pickle.load(file) # G = Instantaneous snapshot of the generator, mainly useful for resuming a previous training run. # D = Instantaneous snapshot of the discriminator, mainly useful for resuming a previous training run. # Gs = Long-term average of the generator, yielding higher-quality results than the instantaneous snapshot.
It is also possible to import networks that were produced using the Theano implementation, as long as they do not employ any features that are not natively supported by the TensorFlow version (minibatch discrimination, batch normalization, etc.). To enable Theano network import, however, you must use
misc.load_pkl()in place of
# Import Theano versions of the official CelebA-HQ networks. import misc G, D, Gs = misc.load_pkl('200-celebahq-1024x1024/network-final.pkl')
Once you have imported the networks, you can call
Gs.run()to produce a set of images for given latent vectors, or
Gs.get_output_for()to include the generator network in a larger TensorFlow expression. For further details, please consult the example script found on Google Drive. Instructions:
pip install -r requirements-pip.txt
networks/tensorflow-versionand place it in the same directory as the script.
img9.png) that match the ones found in
The Progressive GAN code repository contains a command-line tool for recreating bit-exact replicas of the datasets that we used in the paper. The tool also provides various utilities for operating on the datasets:
usage: dataset_tool.py [-h] ...
display Display images in dataset. extract Extract images from dataset. compare Compare two datasets. create_mnist Create dataset for MNIST. create_mnistrgb Create dataset for MNIST-RGB. create_cifar10 Create dataset for CIFAR-10. create_cifar100 Create dataset for CIFAR-100. create_svhn Create dataset for SVHN. create_lsun Create dataset for single LSUN category. create_celeba Create dataset for CelebA. create_celebahq Create dataset for CelebA-HQ. create_from_images Create dataset from a directory full of images. create_from_hdf5 Create dataset from legacy HDF5 archive.
Type "dataset_tool.py -h" for more information.
The datasets are represented by directories containing the same image data in several resolutions to enable efficient streaming. There is a separate
*.tfrecordsfile for each resolution, and if the dataset contains labels, they are stored in a separate file as well:
> python dataset_tool.py create_cifar10 datasets/cifar10 ~/downloads/cifar10 > ls -la datasets/cifar10 drwxr-xr-x 2 user user 7 Feb 21 10:07 . drwxrwxr-x 10 user user 62 Apr 3 15:10 .. -rw-r--r-- 1 user user 4900000 Feb 19 13:17 cifar10-r02.tfrecords -rw-r--r-- 1 user user 12350000 Feb 19 13:17 cifar10-r03.tfrecords -rw-r--r-- 1 user user 41150000 Feb 19 13:17 cifar10-r04.tfrecords -rw-r--r-- 1 user user 156350000 Feb 19 13:17 cifar10-r05.tfrecords -rw-r--r-- 1 user user 2000080 Feb 19 13:17 cifar10-rxx.labels
create_*commands take the standard version of a given dataset as input and produce the corresponding
*.tfrecordsfiles as output. Additionally, the
create_celebahqcommand requires a set of data files representing deltas with respect to the original CelebA dataset. These deltas (27.6GB) can be downloaded from
Note about module versions: Some of the dataset commands require specific versions of Python modules and system libraries (e.g. pillow, libjpeg), and they will give an error if the versions do not match. Please heed the error messages – there is no way to get the commands to work other than installing these specific versions.
Once the necessary datasets are set up, you can proceed to train your own networks. The general procedure is as follows:
config.pyto specify the dataset and training configuration by uncommenting/editing specific lines.
config.pyis configured to train a 1024x1024 network for CelebA-HQ using a single-GPU. This is expected to take about two weeks even on the highest-end NVIDIA GPUs. The key to enabling faster training is to employ multiple GPUs and/or go for a lower-resolution dataset. To this end,
config.pycontains several examples for commonly used datasets, as well as a set of "configuration presets" for multi-GPU training. All of the presets are expected to yield roughly the same image quality for CelebA-HQ, but their total training time can vary considerably:
preset-v1-1gpu: Original config that was used to produce the CelebA-HQ and LSUN results shown in the paper. Expected to take about 1 month on NVIDIA Tesla V100.
preset-v2-1gpu: Optimized config that converges considerably faster than the original one. Expected to take about 2 weeks on 1xV100.
preset-v2-2gpus: Optimized config for 2 GPUs. Takes about 1 week on 2xV100.
preset-v2-4gpus: Optimized config for 4 GPUs. Takes about 3 days on 4xV100.
preset-v2-8gpus: Optimized config for 8 GPUs. Takes about 2 days on 8xV100.
Other noteworthy config options:
fp16: Enable FP16 mixed-precision training to reduce the training times even further. The actual speedup is heavily dependent on GPU architecture and cuDNN version, and it can be expected to increase considerably in the future.
BENCHMARK: Quickly iterate through the resolutions to measure the raw training performance.
BENCHMARK0: Same as
BENCHMARK, but only use the highest resolution.
syn1024rgb: Synthetic 1024x1024 dataset consisting of just black images. Useful for benchmarking.
VERBOSE: Save image and network snapshots very frequently to facilitate debugging.
HIST: Include additional data in the TensorBoard report.
Training results can be analyzed in several ways:
fakes*.pngand reports the overall progress in
*.tfeventsfile that can be visualized in TensorBoard with
config.py, there are several pre-defined configs to launch utility scripts (
generate_*). For example:
010-pgan-celebahq-preset-v1-1gpu-fp32, and you want to generate a video of random interpolations for the latest snapshot.
run_id=10, and run
config.pyalso contains pre-defined configs to compute various quality metrics (Sliced Wasserstein distance, Fréchet inception distance, etc.) for an existing training run. The metrics are computed for each network snapshot in succession and stored in
metric-*.txtin the original result directory.