import math
from typing import Optional, Union
import torch
from torch import nn
from ...configuration_utils import ConfigMixin, register_to_config
from ...models import ModelMixin
from ...models.attention import AdaLayerNorm, FeedForward
from ...models.attention_processor import Attention
from ...models.embeddings import TimestepEmbedding, Timesteps, get_2d_sincos_pos_embed
from ...models.transformer_2d import Transformer2DModelOutput
from ...utils import logging
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
def _no_grad_trunc_normal_(tensor, mean, std, a, b):
# Cut & paste from PyTorch official master until it's in a few official releases - RW
# Method based on https://people.sc.fsu.edu/~jburkardt/presentations/truncated_normal.pdf
def norm_cdf(x):
# Computes standard normal cumulative distribution function
return (1.0 + math.erf(x / math.sqrt(2.0))) / 2.0
if (mean < a - 2 * std) or (mean > b + 2 * std):
logger.warning(
"mean is more than 2 std from [a, b] in nn.init.trunc_normal_. "
"The distribution of values may be incorrect."
)
with torch.no_grad():
# Values are generated by using a truncated uniform distribution and
# then using the inverse CDF for the normal distribution.
# Get upper and lower cdf values
l = norm_cdf((a - mean) / std)
u = norm_cdf((b - mean) / std)
# Uniformly fill tensor with values from [l, u], then translate to
# [2l-1, 2u-1].
tensor.uniform_(2 * l - 1, 2 * u - 1)
# Use inverse cdf transform for normal distribution to get truncated
# standard normal
tensor.erfinv_()
# Transform to proper mean, std
tensor.mul_(std * math.sqrt(2.0))
tensor.add_(mean)
# Clamp to ensure it's in the proper range
tensor.clamp_(min=a, max=b)
return tensor
def trunc_normal_(tensor, mean=0.0, std=1.0, a=-2.0, b=2.0):
# type: (torch.Tensor, float, float, float, float) -> torch.Tensor
r"""Fills the input Tensor with values drawn from a truncated
normal distribution. The values are effectively drawn from the normal distribution :math:`\mathcal{N}(\text{mean},
\text{std}^2)` with values outside :math:`[a, b]` redrawn until they are within the bounds. The method used for
generating the random values works best when :math:`a \leq \text{mean} \leq b`.
Args:
tensor: an n-dimensional `torch.Tensor`
mean: the mean of the normal distribution
std: the standard deviation of the normal distribution
a: the minimum cutoff value
b: the maximum cutoff value
Examples:
>>> w = torch.empty(3, 5) >>> nn.init.trunc_normal_(w)
"""
return _no_grad_trunc_normal_(tensor, mean, std, a, b)
class PatchEmbed(nn.Module):
"""2D Image to Patch Embedding"""
def __init__(
self,
height=224,
width=224,
patch_size=16,
in_channels=3,
embed_dim=768,
layer_norm=False,
flatten=True,
bias=True,
use_pos_embed=True,
):
super().__init__()
num_patches = (height // patch_size) * (width // patch_size)
self.flatten = flatten
self.layer_norm = layer_norm
self.proj = nn.Conv2d(
in_channels, embed_dim, kernel_size=(patch_size, patch_size), stride=patch_size, bias=bias
)
if layer_norm:
self.norm = nn.LayerNorm(embed_dim, elementwise_affine=False, eps=1e-6)
else:
self.norm = None
self.use_pos_embed = use_pos_embed
if self.use_pos_embed:
pos_embed = get_2d_sincos_pos_embed(embed_dim, int(num_patches**0.5))
self.register_buffer("pos_embed", torch.from_numpy(pos_embed).float().unsqueeze(0), persistent=False)
def forward(self, latent):
latent = self.proj(latent)
if self.flatten:
latent = latent.flatten(2).transpose(1, 2) # BCHW -> BNC
if self.layer_norm:
latent = self.norm(latent)
if self.use_pos_embed:
return latent + self.pos_embed
else:
return latent
class SkipBlock(nn.Module):
def __init__(self, dim: int):
super().__init__()
self.skip_linear = nn.Linear(2 * dim, dim)
# Use torch.nn.LayerNorm for now, following the original code
self.norm = nn.LayerNorm(dim)
def forward(self, x, skip):
x = self.skip_linear(torch.cat([x, skip], dim=-1))
x = self.norm(x)
return x
# Modified to support both pre-LayerNorm and post-LayerNorm configurations
# Don't support AdaLayerNormZero for now
# Modified from diffusers.models.attention.BasicTransformerBlock
class UTransformerBlock(nn.Module):
r"""
A modification of BasicTransformerBlock which supports pre-LayerNorm and post-LayerNorm configurations.
Parameters:
dim (`int`): The number of channels in the input and output.
num_attention_heads (`int`): The number of heads to use for multi-head attention.
attention_head_dim (`int`): The number of channels in each head.
dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
cross_attention_dim (`int`, *optional*): The size of the encoder_hidden_states vector for cross attention.
activation_fn (`str`, *optional*, defaults to `"geglu"`):
Activation function to be used in feed-forward.
num_embeds_ada_norm (:obj: `int`, *optional*):
The number of diffusion steps used during training. See `Transformer2DModel`.
attention_bias (:obj: `bool`, *optional*, defaults to `False`):
Configure if the attentions should contain a bias parameter.
only_cross_attention (`bool`, *optional*):
Whether to use only cross-attention layers. In this case two cross attention layers are used.
double_self_attention (`bool`, *optional*):
Whether to use two self-attention layers. In this case no cross attention layers are used.
upcast_attention (`bool`, *optional*):
Whether to upcast the query and key to float32 when performing the attention calculation.
norm_elementwise_affine (`bool`, *optional*):
Whether to use learnable per-element affine parameters during layer normalization.
norm_type (`str`, defaults to `"layer_norm"`):
The layer norm implementation to use.
pre_layer_norm (`bool`, *optional*):
Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"),
as opposed to after ("post-LayerNorm"). Note that `BasicTransformerBlock` uses pre-LayerNorm, e.g.
`pre_layer_norm = True`.
final_dropout (`bool`, *optional*):
Whether to use a final Dropout layer after the feedforward network.
"""
def __init__(
self,
dim: int,
num_attention_heads: int,
attention_head_dim: int,
dropout=0.0,
cross_attention_dim: Optional[int] = None,
activation_fn: str = "geglu",
num_embeds_ada_norm: Optional[int] = None,
attention_bias: bool = False,
only_cross_attention: bool = False,
double_self_attention: bool = False,
upcast_attention: bool = False,
norm_elementwise_affine: bool = True,
norm_type: str = "layer_norm",
pre_layer_norm: bool = True,
final_dropout: bool = False,
):
super().__init__()
self.only_cross_attention = only_cross_attention
self.use_ada_layer_norm = (num_embeds_ada_norm is not None) and norm_type == "ada_norm"
self.pre_layer_norm = pre_layer_norm
if norm_type in ("ada_norm", "ada_norm_zero") and num_embeds_ada_norm is None:
raise ValueError(
f"`norm_type` is set to {norm_type}, but `num_embeds_ada_norm` is not defined. Please make sure to"
f" define `num_embeds_ada_norm` if setting `norm_type` to {norm_type}."
)
# 1. Self-Attn
self.attn1 = Attention(
query_dim=dim,
heads=num_attention_heads,
dim_head=attention_head_dim,
dropout=dropout,
bias=attention_bias,
cross_attention_dim=cross_attention_dim if only_cross_attention else None,
upcast_attention=upcast_attention,
)
# 2. Cross-Attn
if cross_attention_dim is not None or double_self_attention:
self.attn2 = Attention(
query_dim=dim,
cross_attention_dim=cross_attention_dim if not double_self_attention else None,
heads=num_attention_heads,
dim_head=attention_head_dim,
dropout=dropout,
bias=attention_bias,
upcast_attention=upcast_attention,
) # is self-attn if encoder_hidden_states is none
else:
self.attn2 = None
if self.use_ada_layer_norm:
self.norm1 = AdaLayerNorm(dim, num_embeds_ada_norm)
else:
self.norm1 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
if cross_attention_dim is not None or double_self_attention:
# We currently only use AdaLayerNormZero for self attention where there will only be one attention block.
# I.e. the number of returned modulation chunks from AdaLayerZero would not make sense if returned during
# the second cross attention block.
self.norm2 = (
AdaLayerNorm(dim, num_embeds_ada_norm)
if self.use_ada_layer_norm
else nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
)
else:
self.norm2 = None
# 3. Feed-forward
self.norm3 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
self.ff = FeedForward(dim, dropout=dropout, activation_fn=activation_fn, final_dropout=final_dropout)
def forward(
self,
hidden_states,
attention_mask=None,
encoder_hidden_states=None,
encoder_attention_mask=None,
timestep=None,
cross_attention_kwargs=None,
class_labels=None,
):
# Pre-LayerNorm
if self.pre_layer_norm:
if self.use_ada_layer_norm:
norm_hidden_states = self.norm1(hidden_states, timestep)
else:
norm_hidden_states = self.norm1(hidden_states)
else:
norm_hidden_states = hidden_states
# 1. Self-Attention
cross_attention_kwargs = cross_attention_kwargs if cross_attention_kwargs is not None else {}
attn_output = self.attn1(
norm_hidden_states,
encoder_hidden_states=encoder_hidden_states if self.only_cross_attention else None,
attention_mask=attention_mask,
**cross_attention_kwargs,
)
# Post-LayerNorm
if not self.pre_layer_norm:
if self.use_ada_layer_norm:
attn_output = self.norm1(attn_output, timestep)
else:
attn_output = self.norm1(attn_output)
hidden_states = attn_output + hidden_states
if self.attn2 is not None:
# Pre-LayerNorm
if self.pre_layer_norm:
norm_hidden_states = (
self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states)
)
else:
norm_hidden_states = hidden_states
# TODO (Birch-San): Here we should prepare the encoder_attention mask correctly
# prepare attention mask here
# 2. Cross-Attention
attn_output = self.attn2(
norm_hidden_states,
encoder_hidden_states=encoder_hidden_states,
attention_mask=encoder_attention_mask,
**cross_attention_kwargs,
)
# Post-LayerNorm
if not self.pre_layer_norm:
attn_output = self.norm2(attn_output, timestep) if self.use_ada_layer_norm else self.norm2(attn_output)
hidden_states = attn_output + hidden_states
# 3. Feed-forward
# Pre-LayerNorm
if self.pre_layer_norm:
norm_hidden_states = self.norm3(hidden_states)
else:
norm_hidden_states = hidden_states
ff_output = self.ff(norm_hidden_states)
# Post-LayerNorm
if not self.pre_layer_norm:
ff_output = self.norm3(ff_output)
hidden_states = ff_output + hidden_states
return hidden_states
# Like UTransformerBlock except with LayerNorms on the residual backbone of the block
# Modified from diffusers.models.attention.BasicTransformerBlock
class UniDiffuserBlock(nn.Module):
r"""
A modification of BasicTransformerBlock which supports pre-LayerNorm and post-LayerNorm configurations and puts the
LayerNorms on the residual backbone of the block. This matches the transformer block in the [original UniDiffuser
implementation](https://github.com/thu-ml/unidiffuser/blob/main/libs/uvit_multi_post_ln_v1.py#L104).
Parameters:
dim (`int`): The number of channels in the input and output.
num_attention_heads (`int`): The number of heads to use for multi-head attention.
attention_head_dim (`int`): The number of channels in each head.
dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
cross_attention_dim (`int`, *optional*): The size of the encoder_hidden_states vector for cross attention.
activation_fn (`str`, *optional*, defaults to `"geglu"`):
Activation function to be used in feed-forward.
num_embeds_ada_norm (:obj: `int`, *optional*):
The number of diffusion steps used during training. See `Transformer2DModel`.
attention_bias (:obj: `bool`, *optional*, defaults to `False`):
Configure if the attentions should contain a bias parameter.
only_cross_attention (`bool`, *optional*):
Whether to use only cross-attention layers. In this case two cross attention layers are used.
double_self_attention (`bool`, *optional*):
Whether to use two self-attention layers. In this case no cross attention layers are used.
upcast_attention (`bool`, *optional*):
Whether to upcast the query and key to float() when performing the attention calculation.
norm_elementwise_affine (`bool`, *optional*):
Whether to use learnable per-element affine parameters during layer normalization.
norm_type (`str`, defaults to `"layer_norm"`):
The layer norm implementation to use.
pre_layer_norm (`bool`, *optional*):
Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"),
as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm
(`pre_layer_norm = False`).
final_dropout (`bool`, *optional*):
Whether to use a final Dropout layer after the feedforward network.
"""
def __init__(
self,
dim: int,
num_attention_heads: int,
attention_head_dim: int,
dropout=0.0,
cross_attention_dim: Optional[int] = None,
activation_fn: str = "geglu",
num_embeds_ada_norm: Optional[int] = None,
attention_bias: bool = False,
only_cross_attention: bool = False,
double_self_attention: bool = False,
upcast_attention: bool = False,
norm_elementwise_affine: bool = True,
norm_type: str = "layer_norm",
pre_layer_norm: bool = False,
final_dropout: bool = True,
):
super().__init__()
self.only_cross_attention = only_cross_attention
self.use_ada_layer_norm = (num_embeds_ada_norm is not None) and norm_type == "ada_norm"
self.pre_layer_norm = pre_layer_norm
if norm_type in ("ada_norm", "ada_norm_zero") and num_embeds_ada_norm is None:
raise ValueError(
f"`norm_type` is set to {norm_type}, but `num_embeds_ada_norm` is not defined. Please make sure to"
f" define `num_embeds_ada_norm` if setting `norm_type` to {norm_type}."
)
# 1. Self-Attn
self.attn1 = Attention(
query_dim=dim,
heads=num_attention_heads,
dim_head=attention_head_dim,
dropout=dropout,
bias=attention_bias,
cross_attention_dim=cross_attention_dim if only_cross_attention else None,
upcast_attention=upcast_attention,
)
# 2. Cross-Attn
if cross_attention_dim is not None or double_self_attention:
self.attn2 = Attention(
query_dim=dim,
cross_attention_dim=cross_attention_dim if not double_self_attention else None,
heads=num_attention_heads,
dim_head=attention_head_dim,
dropout=dropout,
bias=attention_bias,
upcast_attention=upcast_attention,
) # is self-attn if encoder_hidden_states is none
else:
self.attn2 = None
if self.use_ada_layer_norm:
self.norm1 = AdaLayerNorm(dim, num_embeds_ada_norm)
else:
self.norm1 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
if cross_attention_dim is not None or double_self_attention:
# We currently only use AdaLayerNormZero for self attention where there will only be one attention block.
# I.e. the number of returned modulation chunks from AdaLayerZero would not make sense if returned during
# the second cross attention block.
self.norm2 = (
AdaLayerNorm(dim, num_embeds_ada_norm)
if self.use_ada_layer_norm
else nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
)
else:
self.norm2 = None
# 3. Feed-forward
self.norm3 = nn.LayerNorm(dim, elementwise_affine=norm_elementwise_affine)
self.ff = FeedForward(dim, dropout=dropout, activation_fn=activation_fn, final_dropout=final_dropout)
def forward(
self,
hidden_states,
attention_mask=None,
encoder_hidden_states=None,
encoder_attention_mask=None,
timestep=None,
cross_attention_kwargs=None,
class_labels=None,
):
# Following the diffusers transformer block implementation, put the LayerNorm on the
# residual backbone
# Pre-LayerNorm
if self.pre_layer_norm:
if self.use_ada_layer_norm:
hidden_states = self.norm1(hidden_states, timestep)
else:
hidden_states = self.norm1(hidden_states)
# 1. Self-Attention
cross_attention_kwargs = cross_attention_kwargs if cross_attention_kwargs is not None else {}
attn_output = self.attn1(
hidden_states,
encoder_hidden_states=encoder_hidden_states if self.only_cross_attention else None,
attention_mask=attention_mask,
**cross_attention_kwargs,
)
hidden_states = attn_output + hidden_states
# Following the diffusers transformer block implementation, put the LayerNorm on the
# residual backbone
# Post-LayerNorm
if not self.pre_layer_norm:
if self.use_ada_layer_norm:
hidden_states = self.norm1(hidden_states, timestep)
else:
hidden_states = self.norm1(hidden_states)
if self.attn2 is not None:
# Pre-LayerNorm
if self.pre_layer_norm:
hidden_states = (
self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states)
)
# TODO (Birch-San): Here we should prepare the encoder_attention mask correctly
# prepare attention mask here
# 2. Cross-Attention
attn_output = self.attn2(
hidden_states,
encoder_hidden_states=encoder_hidden_states,
attention_mask=encoder_attention_mask,
**cross_attention_kwargs,
)
hidden_states = attn_output + hidden_states
# Post-LayerNorm
if not self.pre_layer_norm:
hidden_states = (
self.norm2(hidden_states, timestep) if self.use_ada_layer_norm else self.norm2(hidden_states)
)
# 3. Feed-forward
# Pre-LayerNorm
if self.pre_layer_norm:
hidden_states = self.norm3(hidden_states)
ff_output = self.ff(hidden_states)
hidden_states = ff_output + hidden_states
# Post-LayerNorm
if not self.pre_layer_norm:
hidden_states = self.norm3(hidden_states)
return hidden_states
# Modified from diffusers.models.transformer_2d.Transformer2DModel
# Modify the transformer block structure to be U-Net like following U-ViT
# Only supports patch-style input and torch.nn.LayerNorm currently
# https://github.com/baofff/U-ViT
class UTransformer2DModel(ModelMixin, ConfigMixin):
"""
Transformer model based on the [U-ViT](https://github.com/baofff/U-ViT) architecture for image-like data. Compared
to [`Transformer2DModel`], this model has skip connections between transformer blocks in a "U"-shaped fashion,
similar to a U-Net. Supports only continuous (actual embeddings) inputs, which are embedded via a [`PatchEmbed`]
layer and then reshaped to (b, t, d).
Parameters:
num_attention_heads (`int`, *optional*, defaults to 16): The number of heads to use for multi-head attention.
attention_head_dim (`int`, *optional*, defaults to 88): The number of channels in each head.
in_channels (`int`, *optional*):
Pass if the input is continuous. The number of channels in the input.
out_channels (`int`, *optional*):
The number of output channels; if `None`, defaults to `in_channels`.
num_layers (`int`, *optional*, defaults to 1): The number of layers of Transformer blocks to use.
dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
norm_num_groups (`int`, *optional*, defaults to `32`):
The number of groups to use when performing Group Normalization.
cross_attention_dim (`int`, *optional*): The number of encoder_hidden_states dimensions to use.
attention_bias (`bool`, *optional*):
Configure if the TransformerBlocks' attention should contain a bias parameter.
sample_size (`int`, *optional*): Pass if the input is discrete. The width of the latent images.
Note that this is fixed at training time as it is used for learning a number of position embeddings. See
`ImagePositionalEmbeddings`.
num_vector_embeds (`int`, *optional*):
Pass if the input is discrete. The number of classes of the vector embeddings of the latent pixels.
Includes the class for the masked latent pixel.
patch_size (`int`, *optional*, defaults to 2):
The patch size to use in the patch embedding.
activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward.
num_embeds_ada_norm ( `int`, *optional*): Pass if at least one of the norm_layers is `AdaLayerNorm`.
The number of diffusion steps used during training. Note that this is fixed at training time as it is used
to learn a number of embeddings that are added to the hidden states. During inference, you can denoise for
up to but not more than steps than `num_embeds_ada_norm`.
use_linear_projection (int, *optional*): TODO: Not used
only_cross_attention (`bool`, *optional*):
Whether to use only cross-attention layers. In this case two cross attention layers are used in each
transformer block.
upcast_attention (`bool`, *optional*):
Whether to upcast the query and key to float() when performing the attention calculation.
norm_type (`str`, *optional*, defaults to `"layer_norm"`):
The Layer Normalization implementation to use. Defaults to `torch.nn.LayerNorm`.
block_type (`str`, *optional*, defaults to `"unidiffuser"`):
The transformer block implementation to use. If `"unidiffuser"`, has the LayerNorms on the residual
backbone of each transformer block; otherwise has them in the attention/feedforward branches (the standard
behavior in `diffusers`.)
pre_layer_norm (`bool`, *optional*):
Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"),
as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm
(`pre_layer_norm = False`).
norm_elementwise_affine (`bool`, *optional*):
Whether to use learnable per-element affine parameters during layer normalization.
use_patch_pos_embed (`bool`, *optional*):
Whether to use position embeddings inside the patch embedding layer (`PatchEmbed`).
final_dropout (`bool`, *optional*):
Whether to use a final Dropout layer after the feedforward network.
"""
@register_to_config
def __init__(
self,
num_attention_heads: int = 16,
attention_head_dim: int = 88,
in_channels: Optional[int] = None,
out_channels: Optional[int] = None,
num_layers: int = 1,
dropout: float = 0.0,
norm_num_groups: int = 32,
cross_attention_dim: Optional[int] = None,
attention_bias: bool = False,
sample_size: Optional[int] = None,
num_vector_embeds: Optional[int] = None,
patch_size: Optional[int] = 2,
activation_fn: str = "geglu",
num_embeds_ada_norm: Optional[int] = None,
use_linear_projection: bool = False,
only_cross_attention: bool = False,
upcast_attention: bool = False,
norm_type: str = "layer_norm",
block_type: str = "unidiffuser",
pre_layer_norm: bool = False,
norm_elementwise_affine: bool = True,
use_patch_pos_embed=False,
ff_final_dropout: bool = False,
):
super().__init__()
self.use_linear_projection = use_linear_projection
self.num_attention_heads = num_attention_heads
self.attention_head_dim = attention_head_dim
inner_dim = num_attention_heads * attention_head_dim
# 1. Input
# Only support patch input of shape (batch_size, num_channels, height, width) for now
assert in_channels is not None and patch_size is not None, "Patch input requires in_channels and patch_size."
assert sample_size is not None, "UTransformer2DModel over patched input must provide sample_size"
# 2. Define input layers
self.height = sample_size
self.width = sample_size
self.patch_size = patch_size
self.pos_embed = PatchEmbed(
height=sample_size,
width=sample_size,
patch_size=patch_size,
in_channels=in_channels,
embed_dim=inner_dim,
use_pos_embed=use_patch_pos_embed,
)
# 3. Define transformers blocks
# Modify this to have in_blocks ("downsample" blocks, even though we don't actually downsample), a mid_block,
# and out_blocks ("upsample" blocks). Like a U-Net, there are skip connections from in_blocks to out_blocks in
# a "U"-shaped fashion (e.g. first in_block to last out_block, etc.).
# Quick hack to make the transformer block type configurable
if block_type == "unidiffuser":
block_cls = UniDiffuserBlock
else:
block_cls = UTransformerBlock
self.transformer_in_blocks = nn.ModuleList(
[
block_cls(
inner_dim,
num_attention_heads,
attention_head_dim,
dropout=dropout,
cross_attention_dim=cross_attention_dim,
activation_fn=activation_fn,
num_embeds_ada_norm=num_embeds_ada_norm,
attention_bias=attention_bias,
only_cross_attention=only_cross_attention,
upcast_attention=upcast_attention,
norm_type=norm_type,
pre_layer_norm=pre_layer_norm,
norm_elementwise_affine=norm_elementwise_affine,
final_dropout=ff_final_dropout,
)
for d in range(num_layers // 2)
]
)
self.transformer_mid_block = block_cls(
inner_dim,
num_attention_heads,
attention_head_dim,
dropout=dropout,
cross_attention_dim=cross_attention_dim,
activation_fn=activation_fn,
num_embeds_ada_norm=num_embeds_ada_norm,
attention_bias=attention_bias,
only_cross_attention=only_cross_attention,
upcast_attention=upcast_attention,
norm_type=norm_type,
pre_layer_norm=pre_layer_norm,
norm_elementwise_affine=norm_elementwise_affine,
final_dropout=ff_final_dropout,
)
# For each skip connection, we use a SkipBlock (concatenation + Linear + LayerNorm) to process the inputs
# before each transformer out_block.
self.transformer_out_blocks = nn.ModuleList(
[
nn.ModuleDict(
{
"skip": SkipBlock(
inner_dim,
),
"block": block_cls(
inner_dim,
num_attention_heads,
attention_head_dim,
dropout=dropout,
cross_attention_dim=cross_attention_dim,
activation_fn=activation_fn,
num_embeds_ada_norm=num_embeds_ada_norm,
attention_bias=attention_bias,
only_cross_attention=only_cross_attention,
upcast_attention=upcast_attention,
norm_type=norm_type,
pre_layer_norm=pre_layer_norm,
norm_elementwise_affine=norm_elementwise_affine,
final_dropout=ff_final_dropout,
),
}
)
for d in range(num_layers // 2)
]
)
# 4. Define output layers
self.out_channels = in_channels if out_channels is None else out_channels
# Following the UniDiffuser U-ViT implementation, we process the transformer output with
# a LayerNorm layer with per-element affine params
self.norm_out = nn.LayerNorm(inner_dim)
def forward(
self,
hidden_states,
encoder_hidden_states=None,
timestep=None,
class_labels=None,
cross_attention_kwargs=None,
return_dict: bool = True,
hidden_states_is_embedding: bool = False,
unpatchify: bool = True,
):
"""
Args:
hidden_states ( When discrete, `torch.LongTensor` of shape `(batch size, num latent pixels)`.
When continuous, `torch.FloatTensor` of shape `(batch size, channel, height, width)`): Input
hidden_states
encoder_hidden_states ( `torch.LongTensor` of shape `(batch size, encoder_hidden_states dim)`, *optional*):
Conditional embeddings for cross attention layer. If not given, cross-attention defaults to
self-attention.
timestep ( `torch.long`, *optional*):
Optional timestep to be applied as an embedding in AdaLayerNorm's. Used to indicate denoising step.
class_labels ( `torch.LongTensor` of shape `(batch size, num classes)`, *optional*):
Optional class labels to be applied as an embedding in AdaLayerZeroNorm. Used to indicate class labels
conditioning.
cross_attention_kwargs (*optional*):
Keyword arguments to supply to the cross attention layers, if used.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`models.unet_2d_condition.UNet2DConditionOutput`] instead of a plain tuple.
hidden_states_is_embedding (`bool`, *optional*, defaults to `False`):
Whether or not hidden_states is an embedding directly usable by the transformer. In this case we will
ignore input handling (e.g. continuous, vectorized, etc.) and directly feed hidden_states into the
transformer blocks.
unpatchify (`bool`, *optional*, defaults to `True`):
Whether to unpatchify the transformer output.
Returns:
[`~models.transformer_2d.Transformer2DModelOutput`] or `tuple`:
[`~models.transformer_2d.Transformer2DModelOutput`] if `return_dict` is True, otherwise a `tuple`. When
returning a tuple, the first element is the sample tensor.
"""
# 0. Check inputs
if not unpatchify and return_dict:
raise ValueError(
f"Cannot both define `unpatchify`: {unpatchify} and `return_dict`: {return_dict} since when"
f" `unpatchify` is {unpatchify} the returned output is of shape (batch_size, seq_len, hidden_dim)"
" rather than (batch_size, num_channels, height, width)."
)
# 1. Input
if not hidden_states_is_embedding:
hidden_states = self.pos_embed(hidden_states)
# 2. Blocks
# In ("downsample") blocks
skips = []
for in_block in self.transformer_in_blocks:
hidden_states = in_block(
hidden_states,
encoder_hidden_states=encoder_hidden_states,
timestep=timestep,
cross_attention_kwargs=cross_attention_kwargs,
class_labels=class_labels,
)
skips.append(hidden_states)
# Mid block
hidden_states = self.transformer_mid_block(hidden_states)
# Out ("upsample") blocks
for out_block in self.transformer_out_blocks:
hidden_states = out_block["skip"](hidden_states, skips.pop())
hidden_states = out_block["block"](
hidden_states,
encoder_hidden_states=encoder_hidden_states,
timestep=timestep,
cross_attention_kwargs=cross_attention_kwargs,
class_labels=class_labels,
)
# 3. Output
# Don't support AdaLayerNorm for now, so no conditioning/scale/shift logic
hidden_states = self.norm_out(hidden_states)
# hidden_states = self.proj_out(hidden_states)
if unpatchify:
# unpatchify
height = width = int(hidden_states.shape[1] ** 0.5)
hidden_states = hidden_states.reshape(
shape=(-1, height, width, self.patch_size, self.patch_size, self.out_channels)
)
hidden_states = torch.einsum("nhwpqc->nchpwq", hidden_states)
output = hidden_states.reshape(
shape=(-1, self.out_channels, height * self.patch_size, width * self.patch_size)
)
else:
output = hidden_states
if not return_dict:
return (output,)
return Transformer2DModelOutput(sample=output)
class UniDiffuserModel(ModelMixin, ConfigMixin):
"""
Transformer model for a image-text [UniDiffuser](https://arxiv.org/pdf/2303.06555.pdf) model. This is a
modification of [`UTransformer2DModel`] with input and output heads for the VAE-embedded latent image, the
CLIP-embedded image, and the CLIP-embedded prompt (see paper for more details).
Parameters:
text_dim (`int`): The hidden dimension of the CLIP text model used to embed images.
clip_img_dim (`int`): The hidden dimension of the CLIP vision model used to embed prompts.
num_attention_heads (`int`, *optional*, defaults to 16): The number of heads to use for multi-head attention.
attention_head_dim (`int`, *optional*, defaults to 88): The number of channels in each head.
in_channels (`int`, *optional*):
Pass if the input is continuous. The number of channels in the input.
out_channels (`int`, *optional*):
The number of output channels; if `None`, defaults to `in_channels`.
num_layers (`int`, *optional*, defaults to 1): The number of layers of Transformer blocks to use.
dropout (`float`, *optional*, defaults to 0.0): The dropout probability to use.
norm_num_groups (`int`, *optional*, defaults to `32`):
The number of groups to use when performing Group Normalization.
cross_attention_dim (`int`, *optional*): The number of encoder_hidden_states dimensions to use.
attention_bias (`bool`, *optional*):
Configure if the TransformerBlocks' attention should contain a bias parameter.
sample_size (`int`, *optional*): Pass if the input is discrete. The width of the latent images.
Note that this is fixed at training time as it is used for learning a number of position embeddings. See
`ImagePositionalEmbeddings`.
num_vector_embeds (`int`, *optional*):
Pass if the input is discrete. The number of classes of the vector embeddings of the latent pixels.
Includes the class for the masked latent pixel.
patch_size (`int`, *optional*, defaults to 2):
The patch size to use in the patch embedding.
activation_fn (`str`, *optional*, defaults to `"geglu"`): Activation function to be used in feed-forward.
num_embeds_ada_norm ( `int`, *optional*): Pass if at least one of the norm_layers is `AdaLayerNorm`.
The number of diffusion steps used during training. Note that this is fixed at training time as it is used
to learn a number of embeddings that are added to the hidden states. During inference, you can denoise for
up to but not more than steps than `num_embeds_ada_norm`.
use_linear_projection (int, *optional*): TODO: Not used
only_cross_attention (`bool`, *optional*):
Whether to use only cross-attention layers. In this case two cross attention layers are used in each
transformer block.
upcast_attention (`bool`, *optional*):
Whether to upcast the query and key to float32 when performing the attention calculation.
norm_type (`str`, *optional*, defaults to `"layer_norm"`):
The Layer Normalization implementation to use. Defaults to `torch.nn.LayerNorm`.
block_type (`str`, *optional*, defaults to `"unidiffuser"`):
The transformer block implementation to use. If `"unidiffuser"`, has the LayerNorms on the residual
backbone of each transformer block; otherwise has them in the attention/feedforward branches (the standard
behavior in `diffusers`.)
pre_layer_norm (`bool`, *optional*):
Whether to perform layer normalization before the attention and feedforward operations ("pre-LayerNorm"),
as opposed to after ("post-LayerNorm"). The original UniDiffuser implementation is post-LayerNorm
(`pre_layer_norm = False`).
norm_elementwise_affine (`bool`, *optional*):
Whether to use learnable per-element affine parameters during layer normalization.
use_patch_pos_embed (`bool`, *optional*):
Whether to use position embeddings inside the patch embedding layer (`PatchEmbed`).
ff_final_dropout (`bool`, *optional*):
Whether to use a final Dropout layer after the feedforward network.
use_data_type_embedding (`bool`, *optional*):
Whether to use a data type embedding. This is only relevant for UniDiffuser-v1 style models; UniDiffuser-v1
is continue-trained from UniDiffuser-v0 on non-publically-available data and accepts a `data_type`
argument, which can either be `1` to use the weights trained on non-publically-available data or `0`
otherwise. This argument is subsequently embedded by the data type embedding, if used.
"""
@register_to_config
def __init__(
self,
text_dim: int = 768,
clip_img_dim: int = 512,
num_text_tokens: int = 77,
num_attention_heads: int = 16,
attention_head_dim: int = 88,
in_channels: Optional[int] = None,
out_channels: Optional[int] = None,
num_layers: int = 1,
dropout: float = 0.0,
norm_num_groups: int = 32,
cross_attention_dim: Optional[int] = None,
attention_bias: bool = False,
sample_size: Optional[int] = None,
num_vector_embeds: Optional[int] = None,
patch_size: Optional[int] = None,
activation_fn: str = "geglu",
num_embeds_ada_norm: Optional[int] = None,
use_linear_projection: bool = False,
only_cross_attention: bool = False,
upcast_attention: bool = False,
norm_type: str = "layer_norm",
block_type: str = "unidiffuser",
pre_layer_norm: bool = False,
use_timestep_embedding=False,
norm_elementwise_affine: bool = True,
use_patch_pos_embed=False,
ff_final_dropout: bool = True,
use_data_type_embedding: bool = False,
):
super().__init__()
# 0. Handle dimensions
self.inner_dim = num_attention_heads * attention_head_dim
assert sample_size is not None, "UniDiffuserModel over patched input must provide sample_size"
self.sample_size = sample_size
self.in_channels = in_channels
self.out_channels = in_channels if out_channels is None else out_channels
self.patch_size = patch_size
# Assume image is square...
self.num_patches = (self.sample_size // patch_size) * (self.sample_size // patch_size)
# 1. Define input layers
# 1.1 Input layers for text and image input
# For now, only support patch input for VAE latent image input
self.vae_img_in = PatchEmbed(
height=sample_size,
width=sample_size,
patch_size=patch_size,
in_channels=in_channels,
embed_dim=self.inner_dim,
use_pos_embed=use_patch_pos_embed,
)
self.clip_img_in = nn.Linear(clip_img_dim, self.inner_dim)
self.text_in = nn.Linear(text_dim, self.inner_dim)
# 1.2. Timestep embeddings for t_img, t_text
self.timestep_img_proj = Timesteps(
self.inner_dim,
flip_sin_to_cos=True,
downscale_freq_shift=0,
)
self.timestep_img_embed = (
TimestepEmbedding(
self.inner_dim,
4 * self.inner_dim,
out_dim=self.inner_dim,
)
if use_timestep_embedding
else nn.Identity()
)
self.timestep_text_proj = Timesteps(
self.inner_dim,
flip_sin_to_cos=True,
downscale_freq_shift=0,
)
self.timestep_text_embed = (
TimestepEmbedding(
self.inner_dim,
4 * self.inner_dim,
out_dim=self.inner_dim,
)
if use_timestep_embedding
else nn.Identity()
)
# 1.3. Positional embedding
self.num_text_tokens = num_text_tokens
self.num_tokens = 1 + 1 + num_text_tokens + 1 + self.num_patches
self.pos_embed = nn.Parameter(torch.zeros(1, self.num_tokens, self.inner_dim))
self.pos_embed_drop = nn.Dropout(p=dropout)
trunc_normal_(self.pos_embed, std=0.02)
# 1.4. Handle data type token embeddings for UniDiffuser-V1, if necessary
self.use_data_type_embedding = use_data_type_embedding
if self.use_data_type_embedding:
self.data_type_token_embedding = nn.Embedding(2, self.inner_dim)
self.data_type_pos_embed_token = nn.Parameter(torch.zeros(1, 1, self.inner_dim))
# 2. Define transformer blocks
self.transformer = UTransformer2DModel(
num_attention_heads=num_attention_heads,
attention_head_dim=attention_head_dim,
in_channels=in_channels,
out_channels=out_channels,
num_layers=num_layers,
dropout=dropout,
norm_num_groups=norm_num_groups,
cross_attention_dim=cross_attention_dim,
attention_bias=attention_bias,
sample_size=sample_size,
num_vector_embeds=num_vector_embeds,
patch_size=patch_size,
activation_fn=activation_fn,
num_embeds_ada_norm=num_embeds_ada_norm,
use_linear_projection=use_linear_projection,
only_cross_attention=only_cross_attention,
upcast_attention=upcast_attention,
norm_type=norm_type,
block_type=block_type,
pre_layer_norm=pre_layer_norm,
norm_elementwise_affine=norm_elementwise_affine,
use_patch_pos_embed=use_patch_pos_embed,
ff_final_dropout=ff_final_dropout,
)
# 3. Define output layers
patch_dim = (patch_size**2) * out_channels
self.vae_img_out = nn.Linear(self.inner_dim, patch_dim)
self.clip_img_out = nn.Linear(self.inner_dim, clip_img_dim)
self.text_out = nn.Linear(self.inner_dim, text_dim)
@torch.jit.ignore
def no_weight_decay(self):
return {"pos_embed"}
def forward(
self,
latent_image_embeds: torch.FloatTensor,
image_embeds: torch.FloatTensor,
prompt_embeds: torch.FloatTensor,
timestep_img: Union[torch.Tensor, float, int],
timestep_text: Union[torch.Tensor, float, int],
data_type: Optional[Union[torch.Tensor, float, int]] = 1,
encoder_hidden_states=None,
cross_attention_kwargs=None,
):
"""
Args:
latent_image_embeds (`torch.FloatTensor` of shape `(batch size, latent channels, height, width)`):
Latent image representation from the VAE encoder.
image_embeds (`torch.FloatTensor` of shape `(batch size, 1, clip_img_dim)`):
CLIP-embedded image representation (unsqueezed in the first dimension).
prompt_embeds (`torch.FloatTensor` of shape `(batch size, seq_len, text_dim)`):
CLIP-embedded text representation.
timestep_img (`torch.long` or `float` or `int`):
Current denoising step for the image.
timestep_text (`torch.long` or `float` or `int`):
Current denoising step for the text.
data_type: (`torch.int` or `float` or `int`, *optional*, defaults to `1`):
Only used in UniDiffuser-v1-style models. Can be either `1`, to use weights trained on nonpublic data,
or `0` otherwise.
encoder_hidden_states ( `torch.LongTensor` of shape `(batch size, encoder_hidden_states dim)`, *optional*):
Conditional embeddings for cross attention layer. If not given, cross-attention defaults to
self-attention.
cross_attention_kwargs (*optional*):
Keyword arguments to supply to the cross attention layers, if used.
Returns:
`tuple`: Returns relevant parts of the model's noise prediction: the first element of the tuple is tbe VAE
image embedding, the second element is the CLIP image embedding, and the third element is the CLIP text
embedding.
"""
batch_size = latent_image_embeds.shape[0]
# 1. Input
# 1.1. Map inputs to shape (B, N, inner_dim)
vae_hidden_states = self.vae_img_in(latent_image_embeds)
clip_hidden_states = self.clip_img_in(image_embeds)
text_hidden_states = self.text_in(prompt_embeds)
num_text_tokens, num_img_tokens = text_hidden_states.size(1), vae_hidden_states.size(1)
# 1.2. Encode image timesteps to single token (B, 1, inner_dim)
if not torch.is_tensor(timestep_img):
timestep_img = torch.tensor([timestep_img], dtype=torch.long, device=vae_hidden_states.device)
# broadcast to batch dimension in a way that's compatible with ONNX/Core ML
timestep_img = timestep_img * torch.ones(batch_size, dtype=timestep_img.dtype, device=timestep_img.device)
timestep_img_token = self.timestep_img_proj(timestep_img)
# t_img_token does not contain any weights and will always return f32 tensors
# but time_embedding might be fp16, so we need to cast here.
timestep_img_token = timestep_img_token.to(dtype=self.dtype)
timestep_img_token = self.timestep_img_embed(timestep_img_token)
timestep_img_token = timestep_img_token.unsqueeze(dim=1)
# 1.3. Encode text timesteps to single token (B, 1, inner_dim)
if not torch.is_tensor(timestep_text):
timestep_text = torch.tensor([timestep_text], dtype=torch.long, device=vae_hidden_states.device)
# broadcast to batch dimension in a way that's compatible with ONNX/Core ML
timestep_text = timestep_text * torch.ones(batch_size, dtype=timestep_text.dtype, device=timestep_text.device)
timestep_text_token = self.timestep_text_proj(timestep_text)
# t_text_token does not contain any weights and will always return f32 tensors
# but time_embedding might be fp16, so we need to cast here.
timestep_text_token = timestep_text_token.to(dtype=self.dtype)
timestep_text_token = self.timestep_text_embed(timestep_text_token)
timestep_text_token = timestep_text_token.unsqueeze(dim=1)
# 1.4. Concatenate all of the embeddings together.
if self.use_data_type_embedding:
assert data_type is not None, "data_type must be supplied if the model uses a data type embedding"
if not torch.is_tensor(data_type):
data_type = torch.tensor([data_type], dtype=torch.int, device=vae_hidden_states.device)
# broadcast to batch dimension in a way that's compatible with ONNX/Core ML
data_type = data_type * torch.ones(batch_size, dtype=data_type.dtype, device=data_type.device)
data_type_token = self.data_type_token_embedding(data_type).unsqueeze(dim=1)
hidden_states = torch.cat(
[
timestep_img_token,
timestep_text_token,
data_type_token,
text_hidden_states,
clip_hidden_states,
vae_hidden_states,
],
dim=1,
)
else:
hidden_states = torch.cat(
[timestep_img_token, timestep_text_token, text_hidden_states, clip_hidden_states, vae_hidden_states],
dim=1,
)
# 1.5. Prepare the positional embeddings and add to hidden states
# Note: I think img_vae should always have the proper shape, so there's no need to interpolate
# the position embeddings.
if self.use_data_type_embedding:
pos_embed = torch.cat(
[self.pos_embed[:, : 1 + 1, :], self.data_type_pos_embed_token, self.pos_embed[:, 1 + 1 :, :]], dim=1
)
else:
pos_embed = self.pos_embed
hidden_states = hidden_states + pos_embed
hidden_states = self.pos_embed_drop(hidden_states)
# 2. Blocks
hidden_states = self.transformer(
hidden_states,
encoder_hidden_states=encoder_hidden_states,
timestep=None,
class_labels=None,
cross_attention_kwargs=cross_attention_kwargs,
return_dict=False,
hidden_states_is_embedding=True,
unpatchify=False,
)[0]
# 3. Output
# Split out the predicted noise representation.
if self.use_data_type_embedding:
(
t_img_token_out,
t_text_token_out,
data_type_token_out,
text_out,
img_clip_out,
img_vae_out,
) = hidden_states.split((1, 1, 1, num_text_tokens, 1, num_img_tokens), dim=1)
else:
t_img_token_out, t_text_token_out, text_out, img_clip_out, img_vae_out = hidden_states.split(
(1, 1, num_text_tokens, 1, num_img_tokens), dim=1
)
img_vae_out = self.vae_img_out(img_vae_out)
# unpatchify
height = width = int(img_vae_out.shape[1] ** 0.5)
img_vae_out = img_vae_out.reshape(
shape=(-1, height, width, self.patch_size, self.patch_size, self.out_channels)
)
img_vae_out = torch.einsum("nhwpqc->nchpwq", img_vae_out)
img_vae_out = img_vae_out.reshape(
shape=(-1, self.out_channels, height * self.patch_size, width * self.patch_size)
)
img_clip_out = self.clip_img_out(img_clip_out)
text_out = self.text_out(text_out)
return img_vae_out, img_clip_out, text_out