Generative Adversarial Networks Ian Goodfellow Research Scientist - - PowerPoint PPT Presentation

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Generative Adversarial Networks Ian Goodfellow Research Scientist - - PowerPoint PPT Presentation

Generative Adversarial Networks Ian Goodfellow Research Scientist GPU Technology Conference San Jose, California 2016-04-05 Generative Modeling Have training examples: x p train ( x ) Want a model that can draw samples: x p


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Generative Adversarial Networks

Ian Goodfellow Research Scientist

GPU Technology Conference San Jose, California 2016-04-05

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Generative Modeling

  • Have training examples:
  • Want a model that can draw samples:
  • Want

x ∼ ptrain(x) x ∼ pmodel(x) pmodel(x) = pdata(x) (Images from Toronto Face Database)

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Example Applications

  • Image manipulation
  • Text to speech
  • Machine translation
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Modeling Priorities

x Probability Density

q∗ = argminqDKL(pkq) p(x) q∗(x)

x Probability Density

q∗ = argminqDKL(qkp) p(x) q∗(x)

Put high probability where there should be high probability Put low probability where there should be low probability (Deep Learning, Goodfellow, Bengio, and Courville 2016)

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Generative Adversarial Networks

Input noise Z Differentiable function G x sampled from model Differentiable function D D tries to

  • utput 0

x sampled from data Differentiable function D D tries to

  • utput 1

x x z

(“Generative Adversarial Networks”, Goodfellow et al 2014)

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Discriminator Strategy

D(x) = pdata(x) pdata(x) + pmodel(x)

Data distribution Model distribution

Optimal D(x) for any pdata(x) and pmodel(x) is always

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SLIDE 7

...

Poorly fit model After updating D After updating G Mixed strategy equilibrium Data distribution Model distribution

Discriminator response

Learning Process

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Generator Transformation Videos

MNIST digit dataset Toronto Face Dataset (TFD)

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Non-Convergence

(Alec Radford)

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SLIDE 10

Laplacian Pyramid

(Denton+Chintala et al 2015)

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LAPGAN Results

  • 40% of samples mistaken by humans for real photographs

(Denton+Chintala et al 2015)

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DCGAN Results

(Radford et al 2015)

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Arithmetic on Face Semantics

  • +

=

(Radford et al 2015) Man wearing glasses Man Woman Woman wearing glasses

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Mean Squared Error Ignores Small Details

Input Reconstruction

(Chelsea Finn)

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GANs Learn a Cost Function

Ground Truth MSE Adversarial

(Lotter et al, 2015) Capture predictable details regardless of scale

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Conclusion

  • Generative adversarial nets
  • Prioritize generating realistic samples over

assigning high probability to all samples

  • Learn a cost function instead of using a fixed cost

function

  • Learn that all predictable structures are important,

even if they are small or faint