lukemelas/pytorch-pretrained-gans

Quick Start

This repository provides a standardized interface for pretrained GANs in PyTorch. You can install it with:

pip install git+https://github.com/lukemelas/pytorch-pretrained-gans

It is then easy to generate an image with a GAN:

import torch
from pytorch_pretrained_gans import make_gan

# Sample a class-conditional image from BigGAN with default resolution 256
G = make_gan(gan_type='biggan')  # -> nn.Module
y = G.sample_class(batch_size=1)  # -> torch.Size([1, 1000])
z = G.sample_latent(batch_size=1)  # -> torch.Size([1, 128])
x = G(z=z, y=y)  # -> torch.Size([1, 3, 256, 256])

Motivation

Over the past few years, great progress has been made in generative modeling using GANs. As a result, a large body of research has emerged that uses GANs and explores/interprets their latent spaces. I recently worked on a project in which I wanted to apply the same technique to a bunch of different GANs (here's the paper if you're interested). This was quite a pain because all the pretrained GANs out there are in completely different formats. So I decided to standardize them, and here's the result. I hope you find it useful.

Installation

Install with pip directly from GitHub:

pip install git+https://github.com/lukemelas/pytorch-pretrained-gans

Available GANs

The following GANs are available. If you would like to add a new GAN to the repo, please submit a pull request -- I would love to add to this list:

• BigGAN
• BigBiGAN
• StyleGAN-2-ADA
• Self-Conditioned GANs
• Many GANs from StudioGAN:
  • BigGAN (a reimplementation)
  • ContraGAN
  • SAGAN
  • SNGAN

Structure

This repo supports both conditional and unconditional GANs. The standard GAN interface is as follows:

class GeneratorWrapper(torch.nn.Module):
    """ A wrapper to put the GAN in a standard format."""

    def __init__(self, G, num_classes=None):
        super().__init__()
        self.G : nn.Module =    # GAN generator
        self.dim_z : int =      # dimensionality of latent space
        self.conditional =      # True / False

    def forward(self, z, y=None):  # y is for conditional GAN only
        x =  # ... generate image from latent with self.G
        return x  # returns image

    def sample_latent(self, batch_size, device='cpu'):
        z =  # ... samples latent vector of size self.dim_z
        return z

    def sample_class(self, batch_size, device='cpu'):
        y =  # ... samples class y (for conditional GAN only)
        return y

Each type of GAN is contained in its own folder and has a make_GAN_TYPE function. For example, make_bigbigan creates a BigBiGAN with the format of the GeneratorWrapper above.

The weights of all GANs except those in PyTorch-StudioGAN and are downloaded automatically. To download the PyTorch-StudioGAN weights, use the download.sh scripts in the corresponding folders (see the file structure below).

Code Structure

The structure of the repo is below. Each type of GAN has an __init__.py file that defines its GeneratorWrapper and its make_GAN_TYPE file.

pytorch_pretrained_gans
├── __init__.py
├── BigBiGAN
│   ├── __init__.py
│   ├── ...
│   └── weights
│       └── download.sh   # (use this to download pretrained weights)
├── BigGAN
│   ├── __init__.py   # (pretrained weights are auto-downloaded)
│   ├── ...
├── StudioGAN
│   ├── __init__.py   # (pretrained weights are auto-downloaded)
│   ├── ...
│   ├── configs
│   │   ├── ImageNet
│   │   │   ├── BigGAN2048
│   │   │   │   └── ...
│   │   │   └── download.sh  # (use this to download pretrained weights)
│   │   └── TinyImageNet
│   │       ├── ACGAN
│   │       │   └── ACGAN.json
│   │       ├── ...
│   │       └── download.sh  # (use this to download pretrained weights)
├── self_conditioned
│   ├── __init__.py   # (pretrained weights are auto-downloaded)
│   └── ...
└── stylegan2_ada_pytorch
    ├── __init__.py   # (pretrained weights are auto-downloaded)
    └── ...

GAN-Specific Details

Naturally, there are some details that are specific to certain GANs.

BigGAN: For BigGAN, you should specify a resolution with model_name. For example:

• G = make_gan(gan_type='biggan', model_name='biggan-deep-512')

StudioGAN: For StudioGAN, you should specify a model with model_name. For example:

• G = make_gan(gan_type='studiogan', model_name='SAGAN')
• G = make_gan(gan_type='studiogan', model_name='ContraGAN256')

Self-Conditioned GAN: For StudioGAN, you should specify a model (either self_conditioned or unconditional) with model_name. For example:

• G = make_gan(gan_type='selfconditionedgan', model_name='self_conditioned')

StyleGAN 2:

• StyleGAN2's sample_latent method returns w, not z, because this is usually what is desired. w has shape torch.Size([1, 18, 512]).
• StyleGAN2 is currently not implemented on CPU

Citation

Please cite the following if you use this repo in a research paper:

@inproceedings{melaskyriazi2021finding,
  author    = {Melas-Kyriazi, Luke and Rupprecht, Christian and Laina, Iro and Vedaldi, Andrea},
  title     = {Finding an Unsupervised Image Segmenter in each of your Deep Generative Models},
  booktitle = arxiv,
  year      = {2021}
}