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# Copyright 2023 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
# JAX implementation of VQGAN from taming-transformers https://github.com/CompVis/taming-transformers
import math
from functools import partial
from typing import Tuple
import flax
import flax.linen as nn
import jax
import jax.numpy as jnp
from flax.core.frozen_dict import FrozenDict
from ..configuration_utils import ConfigMixin, flax_register_to_config
from ..utils import BaseOutput
from .modeling_flax_utils import FlaxModelMixin
@flax.struct.dataclass
class FlaxDecoderOutput(BaseOutput):
"""
Output of decoding method.
Args:
sample (`jnp.ndarray` of shape `(batch_size, num_channels, height, width)`):
Decoded output sample of the model. Output of the last layer of the model.
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
sample: jnp.ndarray
@flax.struct.dataclass
class FlaxAutoencoderKLOutput(BaseOutput):
"""
Output of AutoencoderKL encoding method.
Args:
latent_dist (`FlaxDiagonalGaussianDistribution`):
Encoded outputs of `Encoder` represented as the mean and logvar of `FlaxDiagonalGaussianDistribution`.
`FlaxDiagonalGaussianDistribution` allows for sampling latents from the distribution.
"""
latent_dist: "FlaxDiagonalGaussianDistribution"
class FlaxUpsample2D(nn.Module):
"""
Flax implementation of 2D Upsample layer
Args:
in_channels (`int`):
Input channels
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
dtype: jnp.dtype = jnp.float32
def setup(self):
self.conv = nn.Conv(
self.in_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
def __call__(self, hidden_states):
batch, height, width, channels = hidden_states.shape
hidden_states = jax.image.resize(
hidden_states,
shape=(batch, height * 2, width * 2, channels),
method="nearest",
)
hidden_states = self.conv(hidden_states)
return hidden_states
class FlaxDownsample2D(nn.Module):
"""
Flax implementation of 2D Downsample layer
Args:
in_channels (`int`):
Input channels
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
dtype: jnp.dtype = jnp.float32
def setup(self):
self.conv = nn.Conv(
self.in_channels,
kernel_size=(3, 3),
strides=(2, 2),
padding="VALID",
dtype=self.dtype,
)
def __call__(self, hidden_states):
pad = ((0, 0), (0, 1), (0, 1), (0, 0)) # pad height and width dim
hidden_states = jnp.pad(hidden_states, pad_width=pad)
hidden_states = self.conv(hidden_states)
return hidden_states
class FlaxResnetBlock2D(nn.Module):
"""
Flax implementation of 2D Resnet Block.
Args:
in_channels (`int`):
Input channels
out_channels (`int`):
Output channels
dropout (:obj:`float`, *optional*, defaults to 0.0):
Dropout rate
groups (:obj:`int`, *optional*, defaults to `32`):
The number of groups to use for group norm.
use_nin_shortcut (:obj:`bool`, *optional*, defaults to `None`):
Whether to use `nin_shortcut`. This activates a new layer inside ResNet block
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
out_channels: int = None
dropout: float = 0.0
groups: int = 32
use_nin_shortcut: bool = None
dtype: jnp.dtype = jnp.float32
def setup(self):
out_channels = self.in_channels if self.out_channels is None else self.out_channels
self.norm1 = nn.GroupNorm(num_groups=self.groups, epsilon=1e-6)
self.conv1 = nn.Conv(
out_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
self.norm2 = nn.GroupNorm(num_groups=self.groups, epsilon=1e-6)
self.dropout_layer = nn.Dropout(self.dropout)
self.conv2 = nn.Conv(
out_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
use_nin_shortcut = self.in_channels != out_channels if self.use_nin_shortcut is None else self.use_nin_shortcut
self.conv_shortcut = None
if use_nin_shortcut:
self.conv_shortcut = nn.Conv(
out_channels,
kernel_size=(1, 1),
strides=(1, 1),
padding="VALID",
dtype=self.dtype,
)
def __call__(self, hidden_states, deterministic=True):
residual = hidden_states
hidden_states = self.norm1(hidden_states)
hidden_states = nn.swish(hidden_states)
hidden_states = self.conv1(hidden_states)
hidden_states = self.norm2(hidden_states)
hidden_states = nn.swish(hidden_states)
hidden_states = self.dropout_layer(hidden_states, deterministic)
hidden_states = self.conv2(hidden_states)
if self.conv_shortcut is not None:
residual = self.conv_shortcut(residual)
return hidden_states + residual
class FlaxAttentionBlock(nn.Module):
r"""
Flax Convolutional based multi-head attention block for diffusion-based VAE.
Parameters:
channels (:obj:`int`):
Input channels
num_head_channels (:obj:`int`, *optional*, defaults to `None`):
Number of attention heads
num_groups (:obj:`int`, *optional*, defaults to `32`):
The number of groups to use for group norm
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
channels: int
num_head_channels: int = None
num_groups: int = 32
dtype: jnp.dtype = jnp.float32
def setup(self):
self.num_heads = self.channels // self.num_head_channels if self.num_head_channels is not None else 1
dense = partial(nn.Dense, self.channels, dtype=self.dtype)
self.group_norm = nn.GroupNorm(num_groups=self.num_groups, epsilon=1e-6)
self.query, self.key, self.value = dense(), dense(), dense()
self.proj_attn = dense()
def transpose_for_scores(self, projection):
new_projection_shape = projection.shape[:-1] + (self.num_heads, -1)
# move heads to 2nd position (B, T, H * D) -> (B, T, H, D)
new_projection = projection.reshape(new_projection_shape)
# (B, T, H, D) -> (B, H, T, D)
new_projection = jnp.transpose(new_projection, (0, 2, 1, 3))
return new_projection
def __call__(self, hidden_states):
residual = hidden_states
batch, height, width, channels = hidden_states.shape
hidden_states = self.group_norm(hidden_states)
hidden_states = hidden_states.reshape((batch, height * width, channels))
query = self.query(hidden_states)
key = self.key(hidden_states)
value = self.value(hidden_states)
# transpose
query = self.transpose_for_scores(query)
key = self.transpose_for_scores(key)
value = self.transpose_for_scores(value)
# compute attentions
scale = 1 / math.sqrt(math.sqrt(self.channels / self.num_heads))
attn_weights = jnp.einsum("...qc,...kc->...qk", query * scale, key * scale)
attn_weights = nn.softmax(attn_weights, axis=-1)
# attend to values
hidden_states = jnp.einsum("...kc,...qk->...qc", value, attn_weights)
hidden_states = jnp.transpose(hidden_states, (0, 2, 1, 3))
new_hidden_states_shape = hidden_states.shape[:-2] + (self.channels,)
hidden_states = hidden_states.reshape(new_hidden_states_shape)
hidden_states = self.proj_attn(hidden_states)
hidden_states = hidden_states.reshape((batch, height, width, channels))
hidden_states = hidden_states + residual
return hidden_states
class FlaxDownEncoderBlock2D(nn.Module):
r"""
Flax Resnet blocks-based Encoder block for diffusion-based VAE.
Parameters:
in_channels (:obj:`int`):
Input channels
out_channels (:obj:`int`):
Output channels
dropout (:obj:`float`, *optional*, defaults to 0.0):
Dropout rate
num_layers (:obj:`int`, *optional*, defaults to 1):
Number of Resnet layer block
resnet_groups (:obj:`int`, *optional*, defaults to `32`):
The number of groups to use for the Resnet block group norm
add_downsample (:obj:`bool`, *optional*, defaults to `True`):
Whether to add downsample layer
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
out_channels: int
dropout: float = 0.0
num_layers: int = 1
resnet_groups: int = 32
add_downsample: bool = True
dtype: jnp.dtype = jnp.float32
def setup(self):
resnets = []
for i in range(self.num_layers):
in_channels = self.in_channels if i == 0 else self.out_channels
res_block = FlaxResnetBlock2D(
in_channels=in_channels,
out_channels=self.out_channels,
dropout=self.dropout,
groups=self.resnet_groups,
dtype=self.dtype,
)
resnets.append(res_block)
self.resnets = resnets
if self.add_downsample:
self.downsamplers_0 = FlaxDownsample2D(self.out_channels, dtype=self.dtype)
def __call__(self, hidden_states, deterministic=True):
for resnet in self.resnets:
hidden_states = resnet(hidden_states, deterministic=deterministic)
if self.add_downsample:
hidden_states = self.downsamplers_0(hidden_states)
return hidden_states
class FlaxUpDecoderBlock2D(nn.Module):
r"""
Flax Resnet blocks-based Decoder block for diffusion-based VAE.
Parameters:
in_channels (:obj:`int`):
Input channels
out_channels (:obj:`int`):
Output channels
dropout (:obj:`float`, *optional*, defaults to 0.0):
Dropout rate
num_layers (:obj:`int`, *optional*, defaults to 1):
Number of Resnet layer block
resnet_groups (:obj:`int`, *optional*, defaults to `32`):
The number of groups to use for the Resnet block group norm
add_upsample (:obj:`bool`, *optional*, defaults to `True`):
Whether to add upsample layer
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
out_channels: int
dropout: float = 0.0
num_layers: int = 1
resnet_groups: int = 32
add_upsample: bool = True
dtype: jnp.dtype = jnp.float32
def setup(self):
resnets = []
for i in range(self.num_layers):
in_channels = self.in_channels if i == 0 else self.out_channels
res_block = FlaxResnetBlock2D(
in_channels=in_channels,
out_channels=self.out_channels,
dropout=self.dropout,
groups=self.resnet_groups,
dtype=self.dtype,
)
resnets.append(res_block)
self.resnets = resnets
if self.add_upsample:
self.upsamplers_0 = FlaxUpsample2D(self.out_channels, dtype=self.dtype)
def __call__(self, hidden_states, deterministic=True):
for resnet in self.resnets:
hidden_states = resnet(hidden_states, deterministic=deterministic)
if self.add_upsample:
hidden_states = self.upsamplers_0(hidden_states)
return hidden_states
class FlaxUNetMidBlock2D(nn.Module):
r"""
Flax Unet Mid-Block module.
Parameters:
in_channels (:obj:`int`):
Input channels
dropout (:obj:`float`, *optional*, defaults to 0.0):
Dropout rate
num_layers (:obj:`int`, *optional*, defaults to 1):
Number of Resnet layer block
resnet_groups (:obj:`int`, *optional*, defaults to `32`):
The number of groups to use for the Resnet and Attention block group norm
attn_num_head_channels (:obj:`int`, *optional*, defaults to `1`):
Number of attention heads for each attention block
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int
dropout: float = 0.0
num_layers: int = 1
resnet_groups: int = 32
attn_num_head_channels: int = 1
dtype: jnp.dtype = jnp.float32
def setup(self):
resnet_groups = self.resnet_groups if self.resnet_groups is not None else min(self.in_channels // 4, 32)
# there is always at least one resnet
resnets = [
FlaxResnetBlock2D(
in_channels=self.in_channels,
out_channels=self.in_channels,
dropout=self.dropout,
groups=resnet_groups,
dtype=self.dtype,
)
]
attentions = []
for _ in range(self.num_layers):
attn_block = FlaxAttentionBlock(
channels=self.in_channels,
num_head_channels=self.attn_num_head_channels,
num_groups=resnet_groups,
dtype=self.dtype,
)
attentions.append(attn_block)
res_block = FlaxResnetBlock2D(
in_channels=self.in_channels,
out_channels=self.in_channels,
dropout=self.dropout,
groups=resnet_groups,
dtype=self.dtype,
)
resnets.append(res_block)
self.resnets = resnets
self.attentions = attentions
def __call__(self, hidden_states, deterministic=True):
hidden_states = self.resnets[0](hidden_states, deterministic=deterministic)
for attn, resnet in zip(self.attentions, self.resnets[1:]):
hidden_states = attn(hidden_states)
hidden_states = resnet(hidden_states, deterministic=deterministic)
return hidden_states
class FlaxEncoder(nn.Module):
r"""
Flax Implementation of VAE Encoder.
This model is a Flax Linen [flax.linen.Module](https://flax.readthedocs.io/en/latest/flax.linen.html#module)
subclass. Use it as a regular Flax linen Module and refer to the Flax documentation for all matter related to
general usage and behavior.
Finally, this model supports inherent JAX features such as:
- [Just-In-Time (JIT) compilation](https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit)
- [Automatic Differentiation](https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation)
- [Vectorization](https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap)
- [Parallelization](https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap)
Parameters:
in_channels (:obj:`int`, *optional*, defaults to 3):
Input channels
out_channels (:obj:`int`, *optional*, defaults to 3):
Output channels
down_block_types (:obj:`Tuple[str]`, *optional*, defaults to `(DownEncoderBlock2D)`):
DownEncoder block type
block_out_channels (:obj:`Tuple[str]`, *optional*, defaults to `(64,)`):
Tuple containing the number of output channels for each block
layers_per_block (:obj:`int`, *optional*, defaults to `2`):
Number of Resnet layer for each block
norm_num_groups (:obj:`int`, *optional*, defaults to `32`):
norm num group
act_fn (:obj:`str`, *optional*, defaults to `silu`):
Activation function
double_z (:obj:`bool`, *optional*, defaults to `False`):
Whether to double the last output channels
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
Parameters `dtype`
"""
in_channels: int = 3
out_channels: int = 3
down_block_types: Tuple[str] = ("DownEncoderBlock2D",)
block_out_channels: Tuple[int] = (64,)
layers_per_block: int = 2
norm_num_groups: int = 32
act_fn: str = "silu"
double_z: bool = False
dtype: jnp.dtype = jnp.float32
def setup(self):
block_out_channels = self.block_out_channels
# in
self.conv_in = nn.Conv(
block_out_channels[0],
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
# downsampling
down_blocks = []
output_channel = block_out_channels[0]
for i, _ in enumerate(self.down_block_types):
input_channel = output_channel
output_channel = block_out_channels[i]
is_final_block = i == len(block_out_channels) - 1
down_block = FlaxDownEncoderBlock2D(
in_channels=input_channel,
out_channels=output_channel,
num_layers=self.layers_per_block,
resnet_groups=self.norm_num_groups,
add_downsample=not is_final_block,
dtype=self.dtype,
)
down_blocks.append(down_block)
self.down_blocks = down_blocks
# middle
self.mid_block = FlaxUNetMidBlock2D(
in_channels=block_out_channels[-1],
resnet_groups=self.norm_num_groups,
attn_num_head_channels=None,
dtype=self.dtype,
)
# end
conv_out_channels = 2 * self.out_channels if self.double_z else self.out_channels
self.conv_norm_out = nn.GroupNorm(num_groups=self.norm_num_groups, epsilon=1e-6)
self.conv_out = nn.Conv(
conv_out_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
def __call__(self, sample, deterministic: bool = True):
# in
sample = self.conv_in(sample)
# downsampling
for block in self.down_blocks:
sample = block(sample, deterministic=deterministic)
# middle
sample = self.mid_block(sample, deterministic=deterministic)
# end
sample = self.conv_norm_out(sample)
sample = nn.swish(sample)
sample = self.conv_out(sample)
return sample
class FlaxDecoder(nn.Module):
r"""
Flax Implementation of VAE Decoder.
This model is a Flax Linen [flax.linen.Module](https://flax.readthedocs.io/en/latest/flax.linen.html#module)
subclass. Use it as a regular Flax linen Module and refer to the Flax documentation for all matter related to
general usage and behavior.
Finally, this model supports inherent JAX features such as:
- [Just-In-Time (JIT) compilation](https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit)
- [Automatic Differentiation](https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation)
- [Vectorization](https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap)
- [Parallelization](https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap)
Parameters:
in_channels (:obj:`int`, *optional*, defaults to 3):
Input channels
out_channels (:obj:`int`, *optional*, defaults to 3):
Output channels
up_block_types (:obj:`Tuple[str]`, *optional*, defaults to `(UpDecoderBlock2D)`):
UpDecoder block type
block_out_channels (:obj:`Tuple[str]`, *optional*, defaults to `(64,)`):
Tuple containing the number of output channels for each block
layers_per_block (:obj:`int`, *optional*, defaults to `2`):
Number of Resnet layer for each block
norm_num_groups (:obj:`int`, *optional*, defaults to `32`):
norm num group
act_fn (:obj:`str`, *optional*, defaults to `silu`):
Activation function
double_z (:obj:`bool`, *optional*, defaults to `False`):
Whether to double the last output channels
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
parameters `dtype`
"""
in_channels: int = 3
out_channels: int = 3
up_block_types: Tuple[str] = ("UpDecoderBlock2D",)
block_out_channels: int = (64,)
layers_per_block: int = 2
norm_num_groups: int = 32
act_fn: str = "silu"
dtype: jnp.dtype = jnp.float32
def setup(self):
block_out_channels = self.block_out_channels
# z to block_in
self.conv_in = nn.Conv(
block_out_channels[-1],
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
# middle
self.mid_block = FlaxUNetMidBlock2D(
in_channels=block_out_channels[-1],
resnet_groups=self.norm_num_groups,
attn_num_head_channels=None,
dtype=self.dtype,
)
# upsampling
reversed_block_out_channels = list(reversed(block_out_channels))
output_channel = reversed_block_out_channels[0]
up_blocks = []
for i, _ in enumerate(self.up_block_types):
prev_output_channel = output_channel
output_channel = reversed_block_out_channels[i]
is_final_block = i == len(block_out_channels) - 1
up_block = FlaxUpDecoderBlock2D(
in_channels=prev_output_channel,
out_channels=output_channel,
num_layers=self.layers_per_block + 1,
resnet_groups=self.norm_num_groups,
add_upsample=not is_final_block,
dtype=self.dtype,
)
up_blocks.append(up_block)
prev_output_channel = output_channel
self.up_blocks = up_blocks
# end
self.conv_norm_out = nn.GroupNorm(num_groups=self.norm_num_groups, epsilon=1e-6)
self.conv_out = nn.Conv(
self.out_channels,
kernel_size=(3, 3),
strides=(1, 1),
padding=((1, 1), (1, 1)),
dtype=self.dtype,
)
def __call__(self, sample, deterministic: bool = True):
# z to block_in
sample = self.conv_in(sample)
# middle
sample = self.mid_block(sample, deterministic=deterministic)
# upsampling
for block in self.up_blocks:
sample = block(sample, deterministic=deterministic)
sample = self.conv_norm_out(sample)
sample = nn.swish(sample)
sample = self.conv_out(sample)
return sample
class FlaxDiagonalGaussianDistribution(object):
def __init__(self, parameters, deterministic=False):
# Last axis to account for channels-last
self.mean, self.logvar = jnp.split(parameters, 2, axis=-1)
self.logvar = jnp.clip(self.logvar, -30.0, 20.0)
self.deterministic = deterministic
self.std = jnp.exp(0.5 * self.logvar)
self.var = jnp.exp(self.logvar)
if self.deterministic:
self.var = self.std = jnp.zeros_like(self.mean)
def sample(self, key):
return self.mean + self.std * jax.random.normal(key, self.mean.shape)
def kl(self, other=None):
if self.deterministic:
return jnp.array([0.0])
if other is None:
return 0.5 * jnp.sum(self.mean**2 + self.var - 1.0 - self.logvar, axis=[1, 2, 3])
return 0.5 * jnp.sum(
jnp.square(self.mean - other.mean) / other.var + self.var / other.var - 1.0 - self.logvar + other.logvar,
axis=[1, 2, 3],
)
def nll(self, sample, axis=[1, 2, 3]):
if self.deterministic:
return jnp.array([0.0])
logtwopi = jnp.log(2.0 * jnp.pi)
return 0.5 * jnp.sum(logtwopi + self.logvar + jnp.square(sample - self.mean) / self.var, axis=axis)
def mode(self):
return self.mean
@flax_register_to_config
class FlaxAutoencoderKL(nn.Module, FlaxModelMixin, ConfigMixin):
r"""
Flax Implementation of Variational Autoencoder (VAE) model with KL loss from the paper Auto-Encoding Variational
Bayes by Diederik P. Kingma and Max Welling.
This model is a Flax Linen [flax.linen.Module](https://flax.readthedocs.io/en/latest/flax.linen.html#module)
subclass. Use it as a regular Flax linen Module and refer to the Flax documentation for all matter related to
general usage and behavior.
Finally, this model supports inherent JAX features such as:
- [Just-In-Time (JIT) compilation](https://jax.readthedocs.io/en/latest/jax.html#just-in-time-compilation-jit)
- [Automatic Differentiation](https://jax.readthedocs.io/en/latest/jax.html#automatic-differentiation)
- [Vectorization](https://jax.readthedocs.io/en/latest/jax.html#vectorization-vmap)
- [Parallelization](https://jax.readthedocs.io/en/latest/jax.html#parallelization-pmap)
Parameters:
in_channels (:obj:`int`, *optional*, defaults to 3):
Input channels
out_channels (:obj:`int`, *optional*, defaults to 3):
Output channels
down_block_types (:obj:`Tuple[str]`, *optional*, defaults to `(DownEncoderBlock2D)`):
DownEncoder block type
up_block_types (:obj:`Tuple[str]`, *optional*, defaults to `(UpDecoderBlock2D)`):
UpDecoder block type
block_out_channels (:obj:`Tuple[str]`, *optional*, defaults to `(64,)`):
Tuple containing the number of output channels for each block
layers_per_block (:obj:`int`, *optional*, defaults to `2`):
Number of Resnet layer for each block
act_fn (:obj:`str`, *optional*, defaults to `silu`):
Activation function
latent_channels (:obj:`int`, *optional*, defaults to `4`):
Latent space channels
norm_num_groups (:obj:`int`, *optional*, defaults to `32`):
Norm num group
sample_size (:obj:`int`, *optional*, defaults to 32):
Sample input size
scaling_factor (`float`, *optional*, defaults to 0.18215):
The component-wise standard deviation of the trained latent space computed using the first batch of the
training set. This is used to scale the latent space to have unit variance when training the diffusion
model. The latents are scaled with the formula `z = z * scaling_factor` before being passed to the
diffusion model. When decoding, the latents are scaled back to the original scale with the formula: `z = 1
/ scaling_factor * z`. For more details, refer to sections 4.3.2 and D.1 of the [High-Resolution Image
Synthesis with Latent Diffusion Models](https://arxiv.org/abs/2112.10752) paper.
dtype (:obj:`jnp.dtype`, *optional*, defaults to jnp.float32):
parameters `dtype`
"""
in_channels: int = 3
out_channels: int = 3
down_block_types: Tuple[str] = ("DownEncoderBlock2D",)
up_block_types: Tuple[str] = ("UpDecoderBlock2D",)
block_out_channels: Tuple[int] = (64,)
layers_per_block: int = 1
act_fn: str = "silu"
latent_channels: int = 4
norm_num_groups: int = 32
sample_size: int = 32
scaling_factor: float = 0.18215
dtype: jnp.dtype = jnp.float32
def setup(self):
self.encoder = FlaxEncoder(
in_channels=self.config.in_channels,
out_channels=self.config.latent_channels,
down_block_types=self.config.down_block_types,
block_out_channels=self.config.block_out_channels,
layers_per_block=self.config.layers_per_block,
act_fn=self.config.act_fn,
norm_num_groups=self.config.norm_num_groups,
double_z=True,
dtype=self.dtype,
)
self.decoder = FlaxDecoder(
in_channels=self.config.latent_channels,
out_channels=self.config.out_channels,
up_block_types=self.config.up_block_types,
block_out_channels=self.config.block_out_channels,
layers_per_block=self.config.layers_per_block,
norm_num_groups=self.config.norm_num_groups,
act_fn=self.config.act_fn,
dtype=self.dtype,
)
self.quant_conv = nn.Conv(
2 * self.config.latent_channels,
kernel_size=(1, 1),
strides=(1, 1),
padding="VALID",
dtype=self.dtype,
)
self.post_quant_conv = nn.Conv(
self.config.latent_channels,
kernel_size=(1, 1),
strides=(1, 1),
padding="VALID",
dtype=self.dtype,
)
def init_weights(self, rng: jax.random.KeyArray) -> FrozenDict:
# init input tensors
sample_shape = (1, self.in_channels, self.sample_size, self.sample_size)
sample = jnp.zeros(sample_shape, dtype=jnp.float32)
params_rng, dropout_rng, gaussian_rng = jax.random.split(rng, 3)
rngs = {"params": params_rng, "dropout": dropout_rng, "gaussian": gaussian_rng}
return self.init(rngs, sample)["params"]
def encode(self, sample, deterministic: bool = True, return_dict: bool = True):
sample = jnp.transpose(sample, (0, 2, 3, 1))
hidden_states = self.encoder(sample, deterministic=deterministic)
moments = self.quant_conv(hidden_states)
posterior = FlaxDiagonalGaussianDistribution(moments)
if not return_dict:
return (posterior,)
return FlaxAutoencoderKLOutput(latent_dist=posterior)
def decode(self, latents, deterministic: bool = True, return_dict: bool = True):
if latents.shape[-1] != self.config.latent_channels:
latents = jnp.transpose(latents, (0, 2, 3, 1))
hidden_states = self.post_quant_conv(latents)
hidden_states = self.decoder(hidden_states, deterministic=deterministic)
hidden_states = jnp.transpose(hidden_states, (0, 3, 1, 2))
if not return_dict:
return (hidden_states,)
return FlaxDecoderOutput(sample=hidden_states)
def __call__(self, sample, sample_posterior=False, deterministic: bool = True, return_dict: bool = True):
posterior = self.encode(sample, deterministic=deterministic, return_dict=return_dict)
if sample_posterior:
rng = self.make_rng("gaussian")
hidden_states = posterior.latent_dist.sample(rng)
else:
hidden_states = posterior.latent_dist.mode()
sample = self.decode(hidden_states, return_dict=return_dict).sample
if not return_dict:
return (sample,)
return FlaxDecoderOutput(sample=sample)
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