Deep Advances in Generative Modeling

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Deep Advances in Generative Modeling Alec Radford @AlecRad March 5 th 2016

Transcript of Deep Advances in Generative Modeling

Page 1: Deep Advances in Generative Modeling

Deep Advances in Generative Modeling

Alec Radford@AlecRad

March 5th 2016

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Generative modelingModeling complex high dimensional data is an open problem.

Deep generative models are currently making progress here.

Various areas of study/application:

unsupervised/representation/manifold learning

generative counterparts of discriminative models

density/likelihood estimation

conditional generation

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Examples of Generative Modeling

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CNNs and RNNs

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Useful Generative Model - Skipthought [1506.06726]

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Two promising approaches

Variational Autoencoders (VAE) Kingma and Welling [1312.6114]

Generative Adversarial Networks (GAN) Goodfellow et al. [1406.2661]

encoder Z decoder x̂X

z generator x̂discriminato

r

X

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Variational Autoencoder

from Kingma and Welling [1312.6114]

● Theoretically elegant autoencoder● Straightforward to implement● Impose a prior on code space

○ regularization○ allows for sampling

● Optimizes variational lower bound on likelihood

encoder Z decoder x̂X

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Generative Adversarial Networks z x̂

discriminator

X

generator

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Generative Adversarial Networks z x̂

discriminator

X

generator

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VAE Extensions

from Kingma et al. [1406.5298]

Semi-Supervised Learning

from Gregor et al. [1502.04623]

DRAW

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GAN Extensions - LAPGAN

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Deep convolutional GANs (DCGAN) [1511.06434]

Luke Metz Soumith ChintalaAlec Radford

tl;dr add more layers

indico indico FAIR

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Deep convolutional GANs (DCGAN) [1511.06434]

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DCGAN Architecture tricks

No fully connected layers

Batch Normalization Ioffe and Szegedy [1502.03167]

Leaky Rectifier in the discriminator

Use Adam Kingma and Ba [1412.6980]

Tweak Adam hyperparameters a bit (lr=0.0002, b1=0.5)

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Really really really ridiculously good looking samples

on constrained image distributions :(

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Interpolation suggests non-overfitting behavior

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Vector arithmetic properties of generator

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Generator disentangles objects from scene?

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Discriminator learns generalizing object detectors

These are responses on validation examples!

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Results on standard supervised tasks

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Conditional DCGAN

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Conditional DCGAN (unpublished)

Sunrise over the ocean

Beautiful falls and stream

sahara desert sand dunes

Tropical rainforest brazil

Stars of the milkyway at night

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IssuesStill not completely stable

especially for deep and higher res

Unconstrained natural images

Even the biggest models underfit

Hard to evaluate

no reliable/straightforward metrics

No inference model

limits kinds of analysis

Little work on conv VAE equivalents

makes comparison difficult

Some funky stuff going on

separate data/sample batchnorm statistics

train with heuristic cost not GAN theory

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Hybridizing VAEs and GANs (best of both worlds?)

from Larsen et. al [1512.09300] from Larsen et. al [1512.09300]

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Hybridizing VAEs and GANs (best of both worlds?)

from Larsen et. al [1512.09300] from Larsen et. al [1512.09300]

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Thanks!

Questions?

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indico.io