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# Copyright 2023 Ollin Boer Bohan and 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.
from dataclasses import dataclass
from typing import Tuple, Union
import torch
from ..configuration_utils import ConfigMixin, register_to_config
from ..utils import BaseOutput, apply_forward_hook
from .modeling_utils import ModelMixin
from .vae import DecoderOutput, DecoderTiny, EncoderTiny
@dataclass
class AutoencoderTinyOutput(BaseOutput):
"""
Output of AutoencoderTiny encoding method.
Args:
latents (`torch.Tensor`): Encoded outputs of the `Encoder`.
"""
latents: torch.Tensor
class AutoencoderTiny(ModelMixin, ConfigMixin):
r"""
A tiny distilled VAE model for encoding images into latents and decoding latent representations into images.
[`AutoencoderTiny`] is a wrapper around the original implementation of `TAESD`.
This model inherits from [`ModelMixin`]. Check the superclass documentation for its generic methods implemented for
all models (such as downloading or saving).
Parameters:
in_channels (`int`, *optional*, defaults to 3): Number of channels in the input image.
out_channels (`int`, *optional*, defaults to 3): Number of channels in the output.
encoder_block_out_channels (`Tuple[int]`, *optional*, defaults to `(64, 64, 64, 64)`):
Tuple of integers representing the number of output channels for each encoder block. The length of the
tuple should be equal to the number of encoder blocks.
decoder_block_out_channels (`Tuple[int]`, *optional*, defaults to `(64, 64, 64, 64)`):
Tuple of integers representing the number of output channels for each decoder block. The length of the
tuple should be equal to the number of decoder blocks.
act_fn (`str`, *optional*, defaults to `"relu"`):
Activation function to be used throughout the model.
latent_channels (`int`, *optional*, defaults to 4):
Number of channels in the latent representation. The latent space acts as a compressed representation of
the input image.
upsampling_scaling_factor (`int`, *optional*, defaults to 2):
Scaling factor for upsampling in the decoder. It determines the size of the output image during the
upsampling process.
num_encoder_blocks (`Tuple[int]`, *optional*, defaults to `(1, 3, 3, 3)`):
Tuple of integers representing the number of encoder blocks at each stage of the encoding process. The
length of the tuple should be equal to the number of stages in the encoder. Each stage has a different
number of encoder blocks.
num_decoder_blocks (`Tuple[int]`, *optional*, defaults to `(3, 3, 3, 1)`):
Tuple of integers representing the number of decoder blocks at each stage of the decoding process. The
length of the tuple should be equal to the number of stages in the decoder. Each stage has a different
number of decoder blocks.
latent_magnitude (`float`, *optional*, defaults to 3.0):
Magnitude of the latent representation. This parameter scales the latent representation values to control
the extent of information preservation.
latent_shift (float, *optional*, defaults to 0.5):
Shift applied to the latent representation. This parameter controls the center of the latent space.
scaling_factor (`float`, *optional*, defaults to 1.0):
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. For this Autoencoder,
however, no such scaling factor was used, hence the value of 1.0 as the default.
force_upcast (`bool`, *optional*, default to `False`):
If enabled it will force the VAE to run in float32 for high image resolution pipelines, such as SD-XL. VAE
can be fine-tuned / trained to a lower range without losing too much precision, in which case
`force_upcast` can be set to `False` (see this fp16-friendly
[AutoEncoder](https://huggingface.co/madebyollin/sdxl-vae-fp16-fix)).
"""
_supports_gradient_checkpointing = True
@register_to_config
def __init__(
self,
in_channels=3,
out_channels=3,
encoder_block_out_channels: Tuple[int] = (64, 64, 64, 64),
decoder_block_out_channels: Tuple[int] = (64, 64, 64, 64),
act_fn: str = "relu",
latent_channels: int = 4,
upsampling_scaling_factor: int = 2,
num_encoder_blocks: Tuple[int] = (1, 3, 3, 3),
num_decoder_blocks: Tuple[int] = (3, 3, 3, 1),
latent_magnitude: int = 3,
latent_shift: float = 0.5,
force_upcast: float = False,
scaling_factor: float = 1.0,
):
super().__init__()
if len(encoder_block_out_channels) != len(num_encoder_blocks):
raise ValueError("`encoder_block_out_channels` should have the same length as `num_encoder_blocks`.")
if len(decoder_block_out_channels) != len(num_decoder_blocks):
raise ValueError("`decoder_block_out_channels` should have the same length as `num_decoder_blocks`.")
self.encoder = EncoderTiny(
in_channels=in_channels,
out_channels=latent_channels,
num_blocks=num_encoder_blocks,
block_out_channels=encoder_block_out_channels,
act_fn=act_fn,
)
self.decoder = DecoderTiny(
in_channels=latent_channels,
out_channels=out_channels,
num_blocks=num_decoder_blocks,
block_out_channels=decoder_block_out_channels,
upsampling_scaling_factor=upsampling_scaling_factor,
act_fn=act_fn,
)
self.latent_magnitude = latent_magnitude
self.latent_shift = latent_shift
self.scaling_factor = scaling_factor
self.use_slicing = False
self.use_tiling = False
# only relevant if vae tiling is enabled
self.spatial_scale_factor = 2**out_channels
self.tile_overlap_factor = 0.125
self.tile_sample_min_size = 512
self.tile_latent_min_size = self.tile_sample_min_size // self.spatial_scale_factor
def _set_gradient_checkpointing(self, module, value=False):
if isinstance(module, (EncoderTiny, DecoderTiny)):
module.gradient_checkpointing = value
def scale_latents(self, x):
"""raw latents -> [0, 1]"""
return x.div(2 * self.latent_magnitude).add(self.latent_shift).clamp(0, 1)
def unscale_latents(self, x):
"""[0, 1] -> raw latents"""
return x.sub(self.latent_shift).mul(2 * self.latent_magnitude)
def enable_slicing(self):
r"""
Enable sliced VAE decoding. When this option is enabled, the VAE will split the input tensor in slices to
compute decoding in several steps. This is useful to save some memory and allow larger batch sizes.
"""
self.use_slicing = True
def disable_slicing(self):
r"""
Disable sliced VAE decoding. If `enable_slicing` was previously enabled, this method will go back to computing
decoding in one step.
"""
self.use_slicing = False
def enable_tiling(self, use_tiling: bool = True):
r"""
Enable tiled VAE decoding. When this option is enabled, the VAE will split the input tensor into tiles to
compute decoding and encoding in several steps. This is useful for saving a large amount of memory and to allow
processing larger images.
"""
self.use_tiling = use_tiling
def disable_tiling(self):
r"""
Disable tiled VAE decoding. If `enable_tiling` was previously enabled, this method will go back to computing
decoding in one step.
"""
self.enable_tiling(False)
def _tiled_encode(self, x: torch.FloatTensor) -> torch.FloatTensor:
r"""Encode a batch of images using a tiled encoder.
When this option is enabled, the VAE will split the input tensor into tiles to compute encoding in several
steps. This is useful to keep memory use constant regardless of image size. To avoid tiling artifacts, the
tiles overlap and are blended together to form a smooth output.
Args:
x (`torch.FloatTensor`): Input batch of images.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.autoencoder_tiny.AutoencoderTinyOutput`] instead of a plain tuple.
Returns:
[`~models.autoencoder_tiny.AutoencoderTinyOutput`] or `tuple`:
If return_dict is True, a [`~models.autoencoder_tiny.AutoencoderTinyOutput`] is returned, otherwise a
plain `tuple` is returned.
"""
# scale of encoder output relative to input
sf = self.spatial_scale_factor
tile_size = self.tile_sample_min_size
# number of pixels to blend and to traverse between tile
blend_size = int(tile_size * self.tile_overlap_factor)
traverse_size = tile_size - blend_size
# tiles index (up/left)
ti = range(0, x.shape[-2], traverse_size)
tj = range(0, x.shape[-1], traverse_size)
# mask for blending
blend_masks = torch.stack(
torch.meshgrid([torch.arange(tile_size / sf) / (blend_size / sf - 1)] * 2, indexing="ij")
)
blend_masks = blend_masks.clamp(0, 1).to(x.device)
# output array
out = torch.zeros(x.shape[0], 4, x.shape[-2] // sf, x.shape[-1] // sf, device=x.device)
for i in ti:
for j in tj:
tile_in = x[..., i : i + tile_size, j : j + tile_size]
# tile result
tile_out = out[..., i // sf : (i + tile_size) // sf, j // sf : (j + tile_size) // sf]
tile = self.encoder(tile_in)
h, w = tile.shape[-2], tile.shape[-1]
# blend tile result into output
blend_mask_i = torch.ones_like(blend_masks[0]) if i == 0 else blend_masks[0]
blend_mask_j = torch.ones_like(blend_masks[1]) if j == 0 else blend_masks[1]
blend_mask = blend_mask_i * blend_mask_j
tile, blend_mask = tile[..., :h, :w], blend_mask[..., :h, :w]
tile_out.copy_(blend_mask * tile + (1 - blend_mask) * tile_out)
return out
def _tiled_decode(self, x: torch.FloatTensor) -> torch.FloatTensor:
r"""Encode a batch of images using a tiled encoder.
When this option is enabled, the VAE will split the input tensor into tiles to compute encoding in several
steps. This is useful to keep memory use constant regardless of image size. To avoid tiling artifacts, the
tiles overlap and are blended together to form a smooth output.
Args:
x (`torch.FloatTensor`): Input batch of images.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.autoencoder_tiny.AutoencoderTinyOutput`] instead of a plain tuple.
Returns:
[`~models.vae.DecoderOutput`] or `tuple`:
If return_dict is True, a [`~models.vae.DecoderOutput`] is returned, otherwise a plain `tuple` is
returned.
"""
# scale of decoder output relative to input
sf = self.spatial_scale_factor
tile_size = self.tile_latent_min_size
# number of pixels to blend and to traverse between tiles
blend_size = int(tile_size * self.tile_overlap_factor)
traverse_size = tile_size - blend_size
# tiles index (up/left)
ti = range(0, x.shape[-2], traverse_size)
tj = range(0, x.shape[-1], traverse_size)
# mask for blending
blend_masks = torch.stack(
torch.meshgrid([torch.arange(tile_size * sf) / (blend_size * sf - 1)] * 2, indexing="ij")
)
blend_masks = blend_masks.clamp(0, 1).to(x.device)
# output array
out = torch.zeros(x.shape[0], 3, x.shape[-2] * sf, x.shape[-1] * sf, device=x.device)
for i in ti:
for j in tj:
tile_in = x[..., i : i + tile_size, j : j + tile_size]
# tile result
tile_out = out[..., i * sf : (i + tile_size) * sf, j * sf : (j + tile_size) * sf]
tile = self.decoder(tile_in)
h, w = tile.shape[-2], tile.shape[-1]
# blend tile result into output
blend_mask_i = torch.ones_like(blend_masks[0]) if i == 0 else blend_masks[0]
blend_mask_j = torch.ones_like(blend_masks[1]) if j == 0 else blend_masks[1]
blend_mask = (blend_mask_i * blend_mask_j)[..., :h, :w]
tile_out.copy_(blend_mask * tile + (1 - blend_mask) * tile_out)
return out
@apply_forward_hook
def encode(
self, x: torch.FloatTensor, return_dict: bool = True
) -> Union[AutoencoderTinyOutput, Tuple[torch.FloatTensor]]:
if self.use_slicing and x.shape[0] > 1:
output = [self._tiled_encode(x_slice) if self.use_tiling else self.encoder(x) for x_slice in x.split(1)]
output = torch.cat(output)
else:
output = self._tiled_encode(x) if self.use_tiling else self.encoder(x)
if not return_dict:
return (output,)
return AutoencoderTinyOutput(latents=output)
@apply_forward_hook
def decode(self, x: torch.FloatTensor, return_dict: bool = True) -> Union[DecoderOutput, Tuple[torch.FloatTensor]]:
if self.use_slicing and x.shape[0] > 1:
output = [self._tiled_decode(x_slice) if self.use_tiling else self.decoder(x) for x_slice in x.split(1)]
output = torch.cat(output)
else:
output = self._tiled_decode(x) if self.use_tiling else self.decoder(x)
# Refer to the following discussion to know why this is needed.
# https://github.com/huggingface/diffusers/pull/4384#discussion_r1279401854
output = output.mul_(2).sub_(1)
if not return_dict:
return (output,)
return DecoderOutput(sample=output)
def forward(
self,
sample: torch.FloatTensor,
return_dict: bool = True,
) -> Union[DecoderOutput, Tuple[torch.FloatTensor]]:
r"""
Args:
sample (`torch.FloatTensor`): Input sample.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`DecoderOutput`] instead of a plain tuple.
"""
enc = self.encode(sample).latents
scaled_enc = self.scale_latents(enc).mul_(255).round_().byte()
unscaled_enc = self.unscale_latents(scaled_enc)
dec = self.decode(unscaled_enc)
if not return_dict:
return (dec,)
return DecoderOutput(sample=dec)