Generative Adversarial Networks (GANs) are a class of machine learning frameworks where two neural networks contest with each other in a game. A generator network generates new data instances, while a discriminator network evaluates them for authenticity, classifying them as real or generated. This adversarial process allows the generator to improve over time and generate highly realistic samples. The document discusses GAN architectures like DCGAN and cGAN, applications for image generation, translation, and deepfakes. It also covers challenges like mode collapse and vanishing gradients.
1. Iranian Society of Machine Vision and Image Processing (ISMVIP)
Intro to Generative
Adversarial Networks (GANs)
Pegah Salehi
2020 - 17 - Dec
Email: pghsalehi@gmail.com
2. Generative Adversarial Networks (GANs)
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[https://thispersondoesnotexist.com/]
Iranian Society of Machine Vision and Image Processing (ISMVIP)
3. The GAN framework
Real Data
D
G
Fake Sample
JD
JG
𝐷(𝑥)
Real
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FakeRandom Noise
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4. The GAN framework
(1)
(2)
(3)
X 𝑑𝑎𝑡𝑎
D
Gz 𝐺(𝑧)
JD
JG
𝐷(𝑥)
Real
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6. Challenges
• Non-convergence: the model parameters oscillate,
destabilize and never converge
• Mode collapse: the generator collapses which
produces limited varieties of samples
• Diminished gradient: the discriminator gets too
successful that the generator gradient vanishes and
learns nothing
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7. Generate New Sample of Image Dataset
DCGA
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BigGA
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StyleGA
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Characteristic
animation
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11. Types of GAN Models
Architectural
Optimization
Objective Function
Optimization
Autoencoder
Conditional
Convolutional
DCGAN
CGAN, infoGAN,
ACGAN, SGAN
AAE, BiGAN, ALI,
AGE, VAE-GAN
Unrolled GAN, f-GAN, Mode-Regularized
GAN, Least-Square GAN, EBGAN,
WGAN, WGAN-GP, WGAN-LP
GenerativeAdversarialNetwork
(GAN)
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12. 32×32×128
4×4×1024
z
Decov 1
Decov 2
Decov 3
Decov 4
8×8×512
16×16×256
64×64×3
G(z)
100 Output
DCGAN
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13. X
D
Gz G z c
Real
or
Fake
C (class)
cGAN
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• Goal: Better control of the generation
• Idea: Add information about the generated sample (e.g., labels) to train the generator
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15. Pix2Pix
Fake Pair
Real
or
Fake
Input
Ground Truth (Reference)
U-net
PatchGAN
Discriminator
Generator
Generated
Tune G by computing L 1 distance
between output and ground truth.
Compute
Adversarial
Loss
Tune G
Tune D
Real Pair
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18. References
1. Salehi, Pegah, Abdolah Chalechale, and Maryam
Taghizadeh. "Generative Adversarial Networks (GANs):
An Overview of Theoretical Model, Evaluation Metrics,
and Recent Developments." arXiv preprint
arXiv:2005.13178 (2020).
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19. Thank you
for your attention...
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