def gumbel_sample(self, reconstr_gan):
hparams = self.hparams
is_training = hparams.mode == tf.estimator.ModeKeys.TRAIN
vocab_size = self._problem_hparams.modality["targets"].top_dimensionality
reconstr_gan = tf.nn.log_softmax(reconstr_gan)
if is_training and hparams.gumbel_temperature > 0.0:
gumbel_samples = discretization.gumbel_sample(
common_layers.shape_list(reconstr_gan))
gumbel_samples *= hparams.gumbel_noise_factor
reconstr_gan += gumbel_samples
reconstr_sample = latent_layers.multinomial_sample(
reconstr_gan, temperature=hparams.gumbel_temperature)
reconstr_gan = tf.nn.softmax(reconstr_gan / hparams.gumbel_temperature)
else:
reconstr_sample = tf.argmax(reconstr_gan, axis=-1)
reconstr_gan = tf.nn.softmax(reconstr_gan / 0.1) # Sharpen a bit.
# Use 1-hot forward, softmax backward.
reconstr_hot = tf.one_hot(reconstr_sample, vocab_size)
reconstr_gan += reconstr_hot - tf.stop_gradient(reconstr_gan)
return reconstr_gan
def pixels_from_softmax(frame_logits, pure_sampling=False,
temperature=1.0, gumbel_noise_factor=0.2):
"""Given frame_logits from a per-pixel softmax, generate colors."""
# If we're purely sampling, just sample each pixel.
if pure_sampling or temperature == 0.0:
return common_layers.sample_with_temperature(frame_logits, temperature)
# Gumbel-sample from the pixel sofmax and average by pixel values.
pixel_range = tf.to_float(tf.range(256))
for _ in range(len(frame_logits.get_shape().as_list()) - 1):
pixel_range = tf.expand_dims(pixel_range, axis=0)
frame_logits = tf.nn.log_softmax(frame_logits)
gumbel_samples = discretization.gumbel_sample(
common_layers.shape_list(frame_logits)) * gumbel_noise_factor
frame = tf.nn.softmax((frame_logits + gumbel_samples) / temperature, axis=-1)
result = tf.reduce_sum(frame * pixel_range, axis=-1)
# Round on the forward pass, not on the backward one.
return result + tf.stop_gradient(tf.round(result) - result)
def gumbel_sample(self, reconstr_gan):
hparams = self.hparams
is_training = hparams.mode == tf.estimator.ModeKeys.TRAIN
vocab_size = self._problem_hparams.modality["targets"].top_dimensionality
reconstr_gan = tf.nn.log_softmax(reconstr_gan)
if is_training and hparams.gumbel_temperature > 0.0:
gumbel_samples = discretization.gumbel_sample(
common_layers.shape_list(reconstr_gan))
gumbel_samples *= hparams.gumbel_noise_factor
reconstr_gan += gumbel_samples
reconstr_sample = latent_layers.multinomial_sample(
reconstr_gan, temperature=hparams.gumbel_temperature)
reconstr_gan = tf.nn.softmax(reconstr_gan / hparams.gumbel_temperature)
else:
reconstr_sample = tf.argmax(reconstr_gan, axis=-1)
reconstr_gan = tf.nn.softmax(reconstr_gan / 0.1) # Sharpen a bit.
# Use 1-hot forward, softmax backward.
reconstr_hot = tf.one_hot(reconstr_sample, vocab_size)
reconstr_gan += reconstr_hot - tf.stop_gradient(reconstr_gan)
return reconstr_gan
def pixels_from_softmax(frame_logits, pure_sampling=False,
temperature=1.0, gumbel_noise_factor=0.2):
"""Given frame_logits from a per-pixel softmax, generate colors."""
# If we're purely sampling, just sample each pixel.
if pure_sampling or temperature == 0.0:
return common_layers.sample_with_temperature(frame_logits, temperature)
# Gumbel-sample from the pixel sofmax and average by pixel values.
pixel_range = tf.to_float(tf.range(256))
for _ in range(len(frame_logits.get_shape().as_list()) - 1):
pixel_range = tf.expand_dims(pixel_range, axis=0)
frame_logits = tf.nn.log_softmax(frame_logits)
gumbel_samples = discretization.gumbel_sample(
common_layers.shape_list(frame_logits)) * gumbel_noise_factor
frame = tf.nn.softmax((frame_logits + gumbel_samples) / temperature, axis=-1)
result = tf.reduce_sum(frame * pixel_range, axis=-1)
# Round on the forward pass, not on the backward one.
return result + tf.stop_gradient(tf.round(result) - result)
def body(self, features):
hparams = self.hparams
is_training = hparams.mode == tf.estimator.ModeKeys.TRAIN
if hparams.mode != tf.estimator.ModeKeys.PREDICT:
labels = features["targets_raw"]
vocab_size = self._problem_hparams.target_modality.top_dimensionality
shape = common_layers.shape_list(labels)
x = tf.one_hot(labels, vocab_size)
x = self.embed(x)
target_codes = x
is1d = shape[2] == 1
self.is1d = is1d
# Run encoder.
x, encoder_layers = self.encoder(x)
# Bottleneck.
b, b_loss = self.bottleneck(x)
xb_loss = 0.0
b_shape = common_layers.shape_list(b)
self._cur_bottleneck_tensor = b
b = self.unbottleneck(b, common_layers.shape_list(x)[-1])
if not is_training:
x = b
else:
l = 2**hparams.num_hidden_layers
warm_step = int(hparams.bottleneck_warmup_steps * 0.25 * l)
nomix_p = common_layers.inverse_lin_decay(warm_step) + 0.01
if common_layers.should_generate_summaries():
tf.summary.scalar("nomix_p_bottleneck", nomix_p)
rand = tf.random_uniform(common_layers.shape_list(x))
# This is the distance between b and x. Having this as loss helps learn
# the bottleneck function, but if we back-propagated to x it would be
# minimized by just setting x=0 and b=0 -- so we don't want too much
# of the influence of this, and we stop-gradient to not zero-out x.
x_stop = tf.stop_gradient(x)
xb_loss = tf.reduce_mean(
tf.reduce_sum(tf.square(x_stop - b), axis=-1))
# To prevent this loss from exploding we clip at 1, but anneal clipping.
clip_max = 1.0 / common_layers.inverse_exp_decay(
warm_step, min_value=0.001)
xb_clip = tf.maximum(tf.stop_gradient(xb_loss), clip_max)
xb_loss *= clip_max / xb_clip
x = tf.where(tf.less(rand, nomix_p), b, x)
if hparams.gan_loss_factor != 0.0:
# Add a purely sampled batch on which we'll compute the GAN loss.
g = self.unbottleneck(self.sample(shape=b_shape),
common_layers.shape_list(x)[-1],
reuse=True)
x = tf.concat([g, x], axis=0)
encoder_layers = [
tf.concat([l, l], axis=0) for l in encoder_layers
]
else:
if self._cur_bottleneck_tensor is None:
b = self.sample()
else:
b = self._cur_bottleneck_tensor
res_size = self.hparams.hidden_size * 2**self.hparams.num_hidden_layers
res_size = min(res_size, hparams.max_hidden_size)
x = self.unbottleneck(b, res_size)
# Run decoder.
x = self.decoder(x, encoder_layers)
if hparams.mode == tf.estimator.ModeKeys.PREDICT:
return x, {"bottleneck_loss": 0.0}
# Cut to the right size and mix before returning.
res = x[:, :shape[1], :shape[2], :]
# Final dense layer.
res = tf.layers.dense(res,
self.num_channels * hparams.hidden_size,
name="res_dense")
output_shape = common_layers.shape_list(res)[:-1] + [
self.num_channels, self.hparams.hidden_size
]
res = tf.reshape(res, output_shape)
if hparams.gan_loss_factor != 0.0:
res_gan, res = tf.split(res, 2, axis=0)
# Losses.
losses = {
"bottleneck_extra": b_loss,
"bottleneck_l2": hparams.bottleneck_l2_factor * xb_loss
}
if hparams.use_vq_loss:
vq_temperature = hparams.vq_temperature / common_layers.inverse_exp_decay(
hparams.gan_codes_warmup_steps * 1.2,
min_value=hparams.vq_temperature * 2)
if hparams.mode != tf.estimator.ModeKeys.TRAIN:
vq_temperature = None
with tf.variable_scope("vq_loss"):
(reconstr, _, target_codes, code_loss,
targets_loss) = discretization.vq_loss(
res, labels, vocab_size, temperature=vq_temperature)
losses["code_loss"] = code_loss * hparams.code_loss_factor
losses["training"] = targets_loss
else:
reconstr = tf.layers.dense(res,
vocab_size,
name="autoencoder_final")
targets_loss = tf.losses.sparse_softmax_cross_entropy(
logits=reconstr, labels=labels)
losses["training"] = targets_loss
# GAN losses.
if hparams.gan_loss_factor != 0.0:
update_means_factor = common_layers.inverse_exp_decay(
hparams.gan_codes_warmup_steps, min_value=0.0001)
if hparams.use_vq_loss:
with tf.variable_scope("vq_loss", reuse=True):
update_means = tf.less(tf.random_uniform([]),
update_means_factor)
reconstr_gan, gan_codes, _, code_loss_gan, _ = discretization.vq_loss(
res_gan,
labels,
vocab_size,
do_update=update_means,
temperature=vq_temperature)
code_loss_gan *= hparams.code_loss_factor * update_means_factor
losses["code_loss_gan"] = code_loss_gan
else:
reconstr_gan = tf.layers.dense(res_gan,
vocab_size,
name="autoencoder_final",
reuse=True)
reconstr_gan = tf.nn.log_softmax(reconstr_gan)
if is_training and hparams.gumbel_temperature > 0.0:
gumbel_samples = discretization.gumbel_sample(
common_layers.shape_list(reconstr_gan))
gumbel_samples *= hparams.gumbel_noise_factor
reconstr_gan += gumbel_samples
reconstr_sample = latent_layers.multinomial_sample(
reconstr_gan, temperature=hparams.gumbel_temperature)
reconstr_gan = tf.nn.softmax(reconstr_gan /
hparams.gumbel_temperature)
else:
reconstr_sample = tf.argmax(reconstr_gan, axis=-1)
reconstr_gan = tf.nn.softmax(reconstr_gan /
0.1) # Sharpen a bit.
# Use 1-hot forward, softmax backward.
reconstr_hot = tf.one_hot(reconstr_sample, vocab_size)
reconstr_gan += reconstr_hot - tf.stop_gradient(reconstr_gan)
# Embed to codes.
gan_codes = self.embed(reconstr_gan)
# Add GAN loss if requested.
gan_loss = 0.0
if hparams.gan_loss_factor != 0.0:
self.image_summary("gan", reconstr_gan)
def discriminate(x):
return self.discriminator(x, is_training=is_training)
tc_shape = common_layers.shape_list(target_codes)
if len(tc_shape) > 4:
target_codes = tf.reshape(
target_codes,
tc_shape[:-2] + [tc_shape[-1] * tc_shape[-2]])
gan_codes = tf.reshape(
gan_codes, tc_shape[:-2] + [tc_shape[-1] * tc_shape[-2]])
gan_lr = common_layers.inverse_exp_decay(
hparams.gan_codes_warmup_steps * 1.5)
rev_grad_gan_codes = reverse_gradient(gan_codes, lr=gan_lr)
gan_loss = common_layers.sliced_gan_loss(
target_codes, rev_grad_gan_codes, discriminate,
self.hparams.num_sliced_vecs)
gan_loss *= hparams.gan_loss_factor * update_means_factor
losses["gan_loss"] = -gan_loss
self.image_summary("ae", reconstr)
logits = reconstr
return logits, losses
