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Detecting CNN-Generated Images [Project Page]

CNN-generated images are surprisingly easy to spot...for now
Sheng-Yu Wang, Oliver Wang, Richard Zhang, Andrew Owens, Alexei A. Efros.
In CVPR, 2020.

This repository contains models, evaluation code, and training code on datasets from our paper. If you would like to run our pretrained model on your image/dataset see (2) Quick start.

Jun 20th 2020 Update Training code and dataset released; test results on uncropped images added (recommended for best performance).

Oct 26th 2020 Update Some reported the download link for training data does not work. If this happens, please try the updated alternative links: 1 and 2

Oct 18th 2021 Update Our method gets 92% AUC on the recently released StyleGAN3 model! For more details, please visit this link.

(1) Setup

Install packages

  • Install PyTorch (
  • pip install -r requirements.txt

Download model weights

  • Run bash weights/

(2) Quick start

Run on a single image

This command runs the model on a single image, and outputs the uncalibrated prediction.

# Model weights need to be downloaded.
python -f examples/real.png -m weights/blur_jpg_prob0.5.pth
python -f examples/fake.png -m weights/blur_jpg_prob0.5.pth

Run on a dataset

This command computes AP and accuracy on a dataset. See the provided directory for an example. Put your real/fake images into the appropriate subfolders to test.

python -d examples/realfakedir -m weights/blur_jpg_prob0.5.pth

(3) Dataset


The testset evaluated in the paper can be downloaded here.

The zip file contains images from 13 CNN-based synthesis algorithms, including the 12 testsets from the paper and images downloaded from Images from each algorithm are stored in a separate folder. In each category, real images are in the 0_real folder, and synthetic images are in the 1_fake folder.

Note: ProGAN, StyleGAN, StyleGAN2, CycleGAN testset contains multiple classes, which are stored in separate subdirectories.

Training set

The training set used in the paper can be downloaded here (Try alternative links 1,2 if the previous link does not work). All images are from LSUN or generated by ProGAN, and they are separated in 20 object categories. Similarly, in each category, real images are in the 0_real folder, and synthetic images are in the 1_fake folder.

Validation set

The validation set consists of held-out ProGAN real and fake images, and can be downloaded here. The directory structure is identical to that of the training set.

Download the dataset

A script for downloading the dataset is as follows:

# Download the testset
cd dataset/test
cd ../..

# Download the training set
cd dataset/train
cd ../..

# Download the validation set
cd dataset/val
cd ../..

If the script doesn't work, an alternative will be to download the zip files manually from the above google drive links. One can place the testset, training, and validation set zip files in dataset/test, dataset/train, and dataset/val folders, respectively, and then unzip the zip files to set everything up.

(4) Train your models

We provide two example scripts to train our Blur+JPEG(0.5) and Blur+JPEG(0.1) models. We use checkpoints/[model_name]/model_epoch_best.pth as our final model.

# Train Blur+JPEG(0.5)
python --name blur_jpg_prob0.5 --blur_prob 0.5 --blur_sig 0.0,3.0 --jpg_prob 0.5 --jpg_method cv2,pil --jpg_qual 30,100 --dataroot ./dataset/ --classes airplane,bird,bicycle,boat,bottle,bus,car,cat,cow,chair,diningtable,dog,person,pottedplant,motorbike,tvmonitor,train,sheep,sofa,horse

# Train Blur+JPEG(0.1)
python --name blur_jpg_prob0.1 --blur_prob 0.1 --blur_sig 0.0,3.0 --jpg_prob 0.1 --jpg_method cv2,pil --jpg_qual 30,100 --dataroot ./dataset/ --classes airplane,bird,bicycle,boat,bottle,bus,car,cat,cow,chair,diningtable,dog,person,pottedplant,motorbike,tvmonitor,train,sheep,sofa,horse

(5) Evaluation

After the testset and the model weights are downloaded, one can evaluate the models by running:

# Run evaluation script. Model weights need to be downloaded. See for flags

Besides print-outs, the results will also be stored in a csv file in the results folder. Configurations such as the path of the dataset, model weight are in, and one can modify the evaluation by changing the configurations.

6/13/2020 Update Additionally, we tested on uncropped images, and observed better performances on most categories. To evaluate without center-cropping:

# Run evaluation script without cropping. Model weights need to be downloaded.
python --no_crop --batch_size 1

The following are the models' performances on the released set, with cropping to 224x224 (as in the paper), and without cropping.


Testset Acc (224) AP (224) Acc (No crop) AP (No crop)
ProGAN 100.0% 100.0% 100.0% 100.0%
StyleGAN 73.4% 98.5% 77.5% 99.3%
BigGAN 59.0% 88.2% 59.5% 90.4%
CycleGAN 80.8% 96.8% 84.6% 97.9%
StarGAN 81.0% 95.4% 84.7% 97.5%
GauGAN 79.3% 98.1% 82.9% 98.8%
CRN 87.6% 98.9% 97.8% 100.0%
IMLE 94.1% 99.5% 98.8% 100.0%
SITD 78.3% 92.7% 93.9% 99.6%
SAN 50.0% 63.9% 50.0% 62.8%
Deepfake 51.1% 66.3% 50.4% 63.1%
StyleGAN2 68.4% 98.0% 72.4% 99.1%
Whichfaceisreal 63.9% 88.8% 75.2% 100.0%


Testset Acc (224) AP (224) Acc (No crop) AP (No crop)
ProGAN 100.0% 100.0% 100.0% 100.0%
StyleGAN 87.1% 99.6% 90.2% 99.8%
BigGAN 70.2% 84.5% 71.2% 86.0%
CycleGAN 85.2% 93.5% 87.6% 94.9%
StarGAN 91.7% 98.2% 94.6% 99.0%
GauGAN 78.9% 89.5% 81.4% 90.8%
CRN 86.3% 98.2% 86.3% 99.8%
IMLE 86.2% 98.4% 86.3% 99.8%
SITD 90.3% 97.2% 98.1% 99.8%
SAN 50.5% 70.5% 50.0% 68.6%
Deepfake 53.5% 89.0% 50.7% 84.5%
StyleGAN2 84.4% 99.1% 86.9% 99.5%
Whichfaceisreal 83.6% 93.2% 91.6% 99.8%

(A) Acknowledgments

This repository borrows partially from the pytorch-CycleGAN-and-pix2pix, and the PyTorch torchvision models repositories.

(B) Citation, Contact

If you find this useful for your research, please consider citing this bibtex. Please contact Sheng-Yu Wang <sheng-yu_wang at berkeley dot edu> with any comments or feedback.


Code for the paper: CNN-generated images are surprisingly easy to spot... for now







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