LibreFLUX / pipeline.py
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# Copyright 2024 Stability AI, The HuggingFace Team, The InstantX Team, and Terminus Research Group. All rights reserved.
#
# Copyright 2024 Black Forest Labs 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.
#
# Originally licensed under the Apache License, Version 2.0 (the "License");
# Updated to "Affero GENERAL PUBLIC LICENSE Version 3, 19 November 2007" via extensive updates to attn_mask usage.
__all__ = ['FluxTransformer2DModelWithMasking', 'CustomPipeline']
from typing import Any, Dict, List, Optional, Union
import torch
import torch.nn as nn
import torch.nn.functional as F
from diffusers.configuration_utils import ConfigMixin, register_to_config
from diffusers.loaders import FromOriginalModelMixin, PeftAdapterMixin
from diffusers.models.attention import FeedForward
from diffusers.models.attention_processor import (
Attention,
apply_rope,
)
from diffusers.models.modeling_utils import ModelMixin
from diffusers.models.normalization import (
AdaLayerNormContinuous,
AdaLayerNormZero,
AdaLayerNormZeroSingle,
)
from diffusers.utils import (
USE_PEFT_BACKEND,
is_torch_version,
logging,
scale_lora_layers,
unscale_lora_layers,
)
from diffusers.utils.torch_utils import maybe_allow_in_graph
from diffusers.models.embeddings import (
CombinedTimestepGuidanceTextProjEmbeddings,
CombinedTimestepTextProjEmbeddings,
)
from diffusers.models.modeling_outputs import Transformer2DModelOutput
from dataclasses import dataclass
from typing import List, Union
import PIL.Image
from diffusers.utils import BaseOutput
import inspect
from functools import lru_cache
from typing import Any, Callable, Dict, List, Optional, Union
import numpy as np
import torch
from transformers import (
CLIPTextModel,
CLIPTokenizer,
T5EncoderModel,
T5TokenizerFast,
)
from diffusers.image_processor import VaeImageProcessor
from diffusers.loaders import SD3LoraLoaderMixin
from diffusers.models.autoencoders import AutoencoderKL
from diffusers.schedulers import FlowMatchEulerDiscreteScheduler
from diffusers.utils import (
USE_PEFT_BACKEND,
is_torch_xla_available,
logging,
replace_example_docstring,
scale_lora_layers,
unscale_lora_layers,
)
from diffusers.utils.torch_utils import randn_tensor
from diffusers.pipelines.pipeline_utils import DiffusionPipeline
if is_torch_xla_available():
import torch_xla.core.xla_model as xm
XLA_AVAILABLE = True
else:
XLA_AVAILABLE = False
@dataclass
class FluxPipelineOutput(BaseOutput):
"""
Output class for Stable Diffusion pipelines.
Args:
images (`List[PIL.Image.Image]` or `np.ndarray`)
List of denoised PIL images of length `batch_size` or numpy array of shape `(batch_size, height, width,
num_channels)`. PIL images or numpy array present the denoised images of the diffusion pipeline.
"""
images: Union[List[PIL.Image.Image], np.ndarray]
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
class FluxSingleAttnProcessor2_0:
r"""
Processor for implementing scaled dot-product attention (enabled by default if you're using PyTorch 2.0).
"""
def __init__(self):
if not hasattr(F, "scaled_dot_product_attention"):
raise ImportError(
"AttnProcessor2_0 requires PyTorch 2.0, to use it, please upgrade PyTorch to 2.0."
)
def __call__(
self,
attn: Attention,
hidden_states: torch.Tensor,
encoder_hidden_states: Optional[torch.Tensor] = None,
attention_mask: Optional[torch.FloatTensor] = None,
image_rotary_emb: Optional[torch.Tensor] = None,
) -> torch.Tensor:
input_ndim = hidden_states.ndim
if input_ndim == 4:
batch_size, channel, height, width = hidden_states.shape
hidden_states = hidden_states.view(
batch_size, channel, height * width
).transpose(1, 2)
batch_size, _, _ = hidden_states.shape
query = attn.to_q(hidden_states)
key = attn.to_k(hidden_states)
value = attn.to_v(hidden_states)
inner_dim = key.shape[-1]
head_dim = inner_dim // attn.heads
query = query.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
key = key.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
value = value.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
if attn.norm_q is not None:
query = attn.norm_q(query)
if attn.norm_k is not None:
key = attn.norm_k(key)
# Apply RoPE if needed
if image_rotary_emb is not None:
# YiYi to-do: update uising apply_rotary_emb
# from ..embeddings import apply_rotary_emb
# query = apply_rotary_emb(query, image_rotary_emb)
# key = apply_rotary_emb(key, image_rotary_emb)
query, key = apply_rope(query, key, image_rotary_emb)
if attention_mask is not None:
attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
attention_mask = (attention_mask > 0).bool()
attention_mask = attention_mask.to(
device=hidden_states.device, dtype=hidden_states.dtype
)
# the output of sdp = (batch, num_heads, seq_len, head_dim)
# TODO: add support for attn.scale when we move to Torch 2.1
hidden_states = F.scaled_dot_product_attention(
query,
key,
value,
dropout_p=0.0,
is_causal=False,
attn_mask=attention_mask,
)
hidden_states = hidden_states.transpose(1, 2).reshape(
batch_size, -1, attn.heads * head_dim
)
hidden_states = hidden_states.to(query.dtype)
if input_ndim == 4:
hidden_states = hidden_states.transpose(-1, -2).reshape(
batch_size, channel, height, width
)
return hidden_states
class FluxAttnProcessor2_0:
"""Attention processor used typically in processing the SD3-like self-attention projections."""
def __init__(self):
if not hasattr(F, "scaled_dot_product_attention"):
raise ImportError(
"FluxAttnProcessor2_0 requires PyTorch 2.0, to use it, please upgrade PyTorch to 2.0."
)
def __call__(
self,
attn: Attention,
hidden_states: torch.FloatTensor,
encoder_hidden_states: torch.FloatTensor = None,
attention_mask: Optional[torch.FloatTensor] = None,
image_rotary_emb: Optional[torch.Tensor] = None,
) -> torch.FloatTensor:
input_ndim = hidden_states.ndim
if input_ndim == 4:
batch_size, channel, height, width = hidden_states.shape
hidden_states = hidden_states.view(
batch_size, channel, height * width
).transpose(1, 2)
context_input_ndim = encoder_hidden_states.ndim
if context_input_ndim == 4:
batch_size, channel, height, width = encoder_hidden_states.shape
encoder_hidden_states = encoder_hidden_states.view(
batch_size, channel, height * width
).transpose(1, 2)
batch_size = encoder_hidden_states.shape[0]
# `sample` projections.
query = attn.to_q(hidden_states)
key = attn.to_k(hidden_states)
value = attn.to_v(hidden_states)
inner_dim = key.shape[-1]
head_dim = inner_dim // attn.heads
query = query.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
key = key.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
value = value.view(batch_size, -1, attn.heads, head_dim).transpose(1, 2)
if attn.norm_q is not None:
query = attn.norm_q(query)
if attn.norm_k is not None:
key = attn.norm_k(key)
# `context` projections.
encoder_hidden_states_query_proj = attn.add_q_proj(encoder_hidden_states)
encoder_hidden_states_key_proj = attn.add_k_proj(encoder_hidden_states)
encoder_hidden_states_value_proj = attn.add_v_proj(encoder_hidden_states)
encoder_hidden_states_query_proj = encoder_hidden_states_query_proj.view(
batch_size, -1, attn.heads, head_dim
).transpose(1, 2)
encoder_hidden_states_key_proj = encoder_hidden_states_key_proj.view(
batch_size, -1, attn.heads, head_dim
).transpose(1, 2)
encoder_hidden_states_value_proj = encoder_hidden_states_value_proj.view(
batch_size, -1, attn.heads, head_dim
).transpose(1, 2)
if attn.norm_added_q is not None:
encoder_hidden_states_query_proj = attn.norm_added_q(
encoder_hidden_states_query_proj
)
if attn.norm_added_k is not None:
encoder_hidden_states_key_proj = attn.norm_added_k(
encoder_hidden_states_key_proj
)
# attention
query = torch.cat([encoder_hidden_states_query_proj, query], dim=2)
key = torch.cat([encoder_hidden_states_key_proj, key], dim=2)
value = torch.cat([encoder_hidden_states_value_proj, value], dim=2)
if image_rotary_emb is not None:
# YiYi to-do: update uising apply_rotary_emb
# from ..embeddings import apply_rotary_emb
# query = apply_rotary_emb(query, image_rotary_emb)
# key = apply_rotary_emb(key, image_rotary_emb)
query, key = apply_rope(query, key, image_rotary_emb)
if attention_mask is not None:
attention_mask = attention_mask.unsqueeze(1).unsqueeze(2)
attention_mask = (attention_mask > 0).bool()
attention_mask = attention_mask.to(
device=hidden_states.device, dtype=hidden_states.dtype
)
hidden_states = F.scaled_dot_product_attention(
query,
key,
value,
dropout_p=0.0,
is_causal=False,
attn_mask=attention_mask,
)
hidden_states = hidden_states.transpose(1, 2).reshape(
batch_size, -1, attn.heads * head_dim
)
hidden_states = hidden_states.to(query.dtype)
encoder_hidden_states, hidden_states = (
hidden_states[:, : encoder_hidden_states.shape[1]],
hidden_states[:, encoder_hidden_states.shape[1] :],
)
# linear proj
hidden_states = attn.to_out[0](hidden_states)
# dropout
hidden_states = attn.to_out[1](hidden_states)
encoder_hidden_states = attn.to_add_out(encoder_hidden_states)
if input_ndim == 4:
hidden_states = hidden_states.transpose(-1, -2).reshape(
batch_size, channel, height, width
)
if context_input_ndim == 4:
encoder_hidden_states = encoder_hidden_states.transpose(-1, -2).reshape(
batch_size, channel, height, width
)
return hidden_states, encoder_hidden_states
# YiYi to-do: refactor rope related functions/classes
def rope(pos: torch.Tensor, dim: int, theta: int) -> torch.Tensor:
assert dim % 2 == 0, "The dimension must be even."
scale = (
torch.arange(
0,
dim,
2,
dtype=torch.float64, # torch.float32 if torch.backends.mps.is_available() else
device=pos.device,
)
/ dim
)
omega = 1.0 / (theta**scale)
batch_size, seq_length = pos.shape
out = torch.einsum("...n,d->...nd", pos, omega)
cos_out = torch.cos(out)
sin_out = torch.sin(out)
stacked_out = torch.stack([cos_out, -sin_out, sin_out, cos_out], dim=-1)
out = stacked_out.view(batch_size, -1, dim // 2, 2, 2)
return out.float()
# YiYi to-do: refactor rope related functions/classes
class EmbedND(nn.Module):
def __init__(self, dim: int, theta: int, axes_dim: List[int]):
super().__init__()
self.dim = dim
self.theta = theta
self.axes_dim = axes_dim
def forward(self, ids: torch.Tensor) -> torch.Tensor:
n_axes = ids.shape[-1]
emb = torch.cat(
[rope(ids[..., i], self.axes_dim[i], self.theta) for i in range(n_axes)],
dim=-3,
)
return emb.unsqueeze(1)
def expand_flux_attention_mask(
hidden_states: torch.Tensor,
attn_mask: torch.Tensor,
) -> torch.Tensor:
"""
Expand a mask so that the image is included.
"""
bsz = attn_mask.shape[0]
assert bsz == hidden_states.shape[0]
residual_seq_len = hidden_states.shape[1]
mask_seq_len = attn_mask.shape[1]
expanded_mask = torch.ones(bsz, residual_seq_len)
expanded_mask[:, :mask_seq_len] = attn_mask
return expanded_mask
@maybe_allow_in_graph
class FluxSingleTransformerBlock(nn.Module):
r"""
A Transformer block following the MMDiT architecture, introduced in Stable Diffusion 3.
Reference: https://arxiv.org/abs/2403.03206
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.
context_pre_only (`bool`): Boolean to determine if we should add some blocks associated with the
processing of `context` conditions.
"""
def __init__(self, dim, num_attention_heads, attention_head_dim, mlp_ratio=4.0):
super().__init__()
self.mlp_hidden_dim = int(dim * mlp_ratio)
self.norm = AdaLayerNormZeroSingle(dim)
self.proj_mlp = nn.Linear(dim, self.mlp_hidden_dim)
self.act_mlp = nn.GELU(approximate="tanh")
self.proj_out = nn.Linear(dim + self.mlp_hidden_dim, dim)
processor = FluxSingleAttnProcessor2_0()
self.attn = Attention(
query_dim=dim,
cross_attention_dim=None,
dim_head=attention_head_dim,
heads=num_attention_heads,
out_dim=dim,
bias=True,
processor=processor,
qk_norm="rms_norm",
eps=1e-6,
pre_only=True,
)
def forward(
self,
hidden_states: torch.FloatTensor,
temb: torch.FloatTensor,
image_rotary_emb=None,
attention_mask: Optional[torch.Tensor] = None,
):
residual = hidden_states
norm_hidden_states, gate = self.norm(hidden_states, emb=temb)
mlp_hidden_states = self.act_mlp(self.proj_mlp(norm_hidden_states))
if attention_mask is not None:
attention_mask = expand_flux_attention_mask(
hidden_states,
attention_mask,
)
attn_output = self.attn(
hidden_states=norm_hidden_states,
image_rotary_emb=image_rotary_emb,
attention_mask=attention_mask,
)
hidden_states = torch.cat([attn_output, mlp_hidden_states], dim=2)
gate = gate.unsqueeze(1)
hidden_states = gate * self.proj_out(hidden_states)
hidden_states = residual + hidden_states
return hidden_states
@maybe_allow_in_graph
class FluxTransformerBlock(nn.Module):
r"""
A Transformer block following the MMDiT architecture, introduced in Stable Diffusion 3.
Reference: https://arxiv.org/abs/2403.03206
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.
context_pre_only (`bool`): Boolean to determine if we should add some blocks associated with the
processing of `context` conditions.
"""
def __init__(
self, dim, num_attention_heads, attention_head_dim, qk_norm="rms_norm", eps=1e-6
):
super().__init__()
self.norm1 = AdaLayerNormZero(dim)
self.norm1_context = AdaLayerNormZero(dim)
if hasattr(F, "scaled_dot_product_attention"):
processor = FluxAttnProcessor2_0()
else:
raise ValueError(
"The current PyTorch version does not support the `scaled_dot_product_attention` function."
)
self.attn = Attention(
query_dim=dim,
cross_attention_dim=None,
added_kv_proj_dim=dim,
dim_head=attention_head_dim,
heads=num_attention_heads,
out_dim=dim,
context_pre_only=False,
bias=True,
processor=processor,
qk_norm=qk_norm,
eps=eps,
)
self.norm2 = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-6)
self.ff = FeedForward(dim=dim, dim_out=dim, activation_fn="gelu-approximate")
self.norm2_context = nn.LayerNorm(dim, elementwise_affine=False, eps=1e-6)
self.ff_context = FeedForward(
dim=dim, dim_out=dim, activation_fn="gelu-approximate"
)
# let chunk size default to None
self._chunk_size = None
self._chunk_dim = 0
def forward(
self,
hidden_states: torch.FloatTensor,
encoder_hidden_states: torch.FloatTensor,
temb: torch.FloatTensor,
image_rotary_emb=None,
attention_mask: Optional[torch.Tensor] = None,
):
norm_hidden_states, gate_msa, shift_mlp, scale_mlp, gate_mlp = self.norm1(
hidden_states, emb=temb
)
norm_encoder_hidden_states, c_gate_msa, c_shift_mlp, c_scale_mlp, c_gate_mlp = (
self.norm1_context(encoder_hidden_states, emb=temb)
)
if attention_mask is not None:
attention_mask = expand_flux_attention_mask(
torch.cat([encoder_hidden_states, hidden_states], dim=1),
attention_mask,
)
# Attention.
attn_output, context_attn_output = self.attn(
hidden_states=norm_hidden_states,
encoder_hidden_states=norm_encoder_hidden_states,
image_rotary_emb=image_rotary_emb,
attention_mask=attention_mask,
)
# Process attention outputs for the `hidden_states`.
attn_output = gate_msa.unsqueeze(1) * attn_output
hidden_states = hidden_states + attn_output
norm_hidden_states = self.norm2(hidden_states)
norm_hidden_states = (
norm_hidden_states * (1 + scale_mlp[:, None]) + shift_mlp[:, None]
)
ff_output = self.ff(norm_hidden_states)
ff_output = gate_mlp.unsqueeze(1) * ff_output
hidden_states = hidden_states + ff_output
# Process attention outputs for the `encoder_hidden_states`.
context_attn_output = c_gate_msa.unsqueeze(1) * context_attn_output
encoder_hidden_states = encoder_hidden_states + context_attn_output
norm_encoder_hidden_states = self.norm2_context(encoder_hidden_states)
norm_encoder_hidden_states = (
norm_encoder_hidden_states * (1 + c_scale_mlp[:, None])
+ c_shift_mlp[:, None]
)
context_ff_output = self.ff_context(norm_encoder_hidden_states)
encoder_hidden_states = (
encoder_hidden_states + c_gate_mlp.unsqueeze(1) * context_ff_output
)
return encoder_hidden_states, hidden_states
class FluxTransformer2DModelWithMasking(
ModelMixin, ConfigMixin, PeftAdapterMixin, FromOriginalModelMixin
):
"""
The Transformer model introduced in Flux.
Reference: https://blackforestlabs.ai/announcing-black-forest-labs/
Parameters:
patch_size (`int`): Patch size to turn the input data into small patches.
in_channels (`int`, *optional*, defaults to 16): The number of channels in the input.
num_layers (`int`, *optional*, defaults to 18): The number of layers of MMDiT blocks to use.
num_single_layers (`int`, *optional*, defaults to 18): The number of layers of single DiT blocks to use.
attention_head_dim (`int`, *optional*, defaults to 64): The number of channels in each head.
num_attention_heads (`int`, *optional*, defaults to 18): The number of heads to use for multi-head attention.
joint_attention_dim (`int`, *optional*): The number of `encoder_hidden_states` dimensions to use.
pooled_projection_dim (`int`): Number of dimensions to use when projecting the `pooled_projections`.
guidance_embeds (`bool`, defaults to False): Whether to use guidance embeddings.
"""
_supports_gradient_checkpointing = True
@register_to_config
def __init__(
self,
patch_size: int = 1,
in_channels: int = 64,
num_layers: int = 19,
num_single_layers: int = 38,
attention_head_dim: int = 128,
num_attention_heads: int = 24,
joint_attention_dim: int = 4096,
pooled_projection_dim: int = 768,
guidance_embeds: bool = False,
axes_dims_rope: List[int] = [16, 56, 56],
):
super().__init__()
self.out_channels = in_channels
self.inner_dim = (
self.config.num_attention_heads * self.config.attention_head_dim
)
self.pos_embed = EmbedND(
dim=self.inner_dim, theta=10000, axes_dim=axes_dims_rope
)
text_time_guidance_cls = (
CombinedTimestepGuidanceTextProjEmbeddings
if guidance_embeds
else CombinedTimestepTextProjEmbeddings
)
self.time_text_embed = text_time_guidance_cls(
embedding_dim=self.inner_dim,
pooled_projection_dim=self.config.pooled_projection_dim,
)
self.context_embedder = nn.Linear(
self.config.joint_attention_dim, self.inner_dim
)
self.x_embedder = torch.nn.Linear(self.config.in_channels, self.inner_dim)
self.transformer_blocks = nn.ModuleList(
[
FluxTransformerBlock(
dim=self.inner_dim,
num_attention_heads=self.config.num_attention_heads,
attention_head_dim=self.config.attention_head_dim,
)
for i in range(self.config.num_layers)
]
)
self.single_transformer_blocks = nn.ModuleList(
[
FluxSingleTransformerBlock(
dim=self.inner_dim,
num_attention_heads=self.config.num_attention_heads,
attention_head_dim=self.config.attention_head_dim,
)
for i in range(self.config.num_single_layers)
]
)
self.norm_out = AdaLayerNormContinuous(
self.inner_dim, self.inner_dim, elementwise_affine=False, eps=1e-6
)
self.proj_out = nn.Linear(
self.inner_dim, patch_size * patch_size * self.out_channels, bias=True
)
self.gradient_checkpointing = False
def _set_gradient_checkpointing(self, module, value=False):
if hasattr(module, "gradient_checkpointing"):
module.gradient_checkpointing = value
def forward(
self,
hidden_states: torch.Tensor,
encoder_hidden_states: torch.Tensor = None,
pooled_projections: torch.Tensor = None,
timestep: torch.LongTensor = None,
img_ids: torch.Tensor = None,
txt_ids: torch.Tensor = None,
guidance: torch.Tensor = None,
joint_attention_kwargs: Optional[Dict[str, Any]] = None,
return_dict: bool = True,
attention_mask: Optional[torch.Tensor] = None,
) -> Union[torch.FloatTensor, Transformer2DModelOutput]:
"""
The [`FluxTransformer2DModelWithMasking`] forward method.
Args:
hidden_states (`torch.FloatTensor` of shape `(batch size, channel, height, width)`):
Input `hidden_states`.
encoder_hidden_states (`torch.FloatTensor` of shape `(batch size, sequence_len, embed_dims)`):
Conditional embeddings (embeddings computed from the input conditions such as prompts) to use.
pooled_projections (`torch.FloatTensor` of shape `(batch_size, projection_dim)`): Embeddings projected
from the embeddings of input conditions.
timestep ( `torch.LongTensor`):
Used to indicate denoising step.
block_controlnet_hidden_states: (`list` of `torch.Tensor`):
A list of tensors that if specified are added to the residuals of transformer blocks.
joint_attention_kwargs (`dict`, *optional*):
A kwargs dictionary that if specified is passed along to the `AttentionProcessor` as defined under
`self.processor` in
[diffusers.models.attention_processor](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py).
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~models.transformer_2d.Transformer2DModelOutput`] instead of a plain
tuple.
Returns:
If `return_dict` is True, an [`~models.transformer_2d.Transformer2DModelOutput`] is returned, otherwise a
`tuple` where the first element is the sample tensor.
"""
if joint_attention_kwargs is not None:
joint_attention_kwargs = joint_attention_kwargs.copy()
lora_scale = joint_attention_kwargs.pop("scale", 1.0)
else:
lora_scale = 1.0
if USE_PEFT_BACKEND:
# weight the lora layers by setting `lora_scale` for each PEFT layer
scale_lora_layers(self, lora_scale)
else:
if (
joint_attention_kwargs is not None
and joint_attention_kwargs.get("scale", None) is not None
):
logger.warning(
"Passing `scale` via `joint_attention_kwargs` when not using the PEFT backend is ineffective."
)
hidden_states = self.x_embedder(hidden_states)
timestep = timestep.to(hidden_states.dtype) * 1000
if guidance is not None:
guidance = guidance.to(hidden_states.dtype) * 1000
else:
guidance = None
temb = (
self.time_text_embed(timestep, pooled_projections)
if guidance is None
else self.time_text_embed(timestep, guidance, pooled_projections)
)
encoder_hidden_states = self.context_embedder(encoder_hidden_states)
ids = torch.cat((txt_ids, img_ids), dim=1)
image_rotary_emb = self.pos_embed(ids)
for index_block, block in enumerate(self.transformer_blocks):
if self.training and self.gradient_checkpointing:
def create_custom_forward(module, return_dict=None):
def custom_forward(*inputs):
if return_dict is not None:
return module(*inputs, return_dict=return_dict)
else:
return module(*inputs)
return custom_forward
ckpt_kwargs: Dict[str, Any] = (
{"use_reentrant": False} if is_torch_version(">=", "1.11.0") else {}
)
encoder_hidden_states, hidden_states = (
torch.utils.checkpoint.checkpoint(
create_custom_forward(block),
hidden_states,
encoder_hidden_states,
temb,
image_rotary_emb,
attention_mask,
**ckpt_kwargs,
)
)
else:
encoder_hidden_states, hidden_states = block(
hidden_states=hidden_states,
encoder_hidden_states=encoder_hidden_states,
temb=temb,
image_rotary_emb=image_rotary_emb,
attention_mask=attention_mask,
)
# Flux places the text tokens in front of the image tokens in the
# sequence.
hidden_states = torch.cat([encoder_hidden_states, hidden_states], dim=1)
for index_block, block in enumerate(self.single_transformer_blocks):
if self.training and self.gradient_checkpointing:
def create_custom_forward(module, return_dict=None):
def custom_forward(*inputs):
if return_dict is not None:
return module(*inputs, return_dict=return_dict)
else:
return module(*inputs)
return custom_forward
ckpt_kwargs: Dict[str, Any] = (
{"use_reentrant": False} if is_torch_version(">=", "1.11.0") else {}
)
hidden_states = torch.utils.checkpoint.checkpoint(
create_custom_forward(block),
hidden_states,
temb,
image_rotary_emb,
attention_mask,
**ckpt_kwargs,
)
else:
hidden_states = block(
hidden_states=hidden_states,
temb=temb,
image_rotary_emb=image_rotary_emb,
attention_mask=attention_mask,
)
hidden_states = hidden_states[:, encoder_hidden_states.shape[1] :, ...]
hidden_states = self.norm_out(hidden_states, temb)
output = self.proj_out(hidden_states)
if USE_PEFT_BACKEND:
# remove `lora_scale` from each PEFT layer
unscale_lora_layers(self, lora_scale)
if not return_dict:
return (output,)
return Transformer2DModelOutput(sample=output)
EXAMPLE_DOC_STRING = """
Examples:
```py
>>> import torch
>>> from diffusers import FluxPipeline
>>> pipe = FluxPipeline.from_pretrained("black-forest-labs/FLUX.1-schnell", torch_dtype=torch.bfloat16)
>>> pipe.to("cuda")
>>> prompt = "A cat holding a sign that says hello world"
>>> # Depending on the variant being used, the pipeline call will slightly vary.
>>> # Refer to the pipeline documentation for more details.
>>> image = pipe(prompt, num_inference_steps=4, guidance_scale=0.0).images[0]
>>> image.save("flux.png")
```
"""
def calculate_shift(
image_seq_len,
base_seq_len: int = 256,
max_seq_len: int = 4096,
base_shift: float = 0.5,
max_shift: float = 1.16,
):
m = (max_shift - base_shift) / (max_seq_len - base_seq_len)
b = base_shift - m * base_seq_len
mu = image_seq_len * m + b
return mu
# Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.retrieve_timesteps
def retrieve_timesteps(
scheduler,
num_inference_steps: Optional[int] = None,
device: Optional[Union[str, torch.device]] = None,
timesteps: Optional[List[int]] = None,
sigmas: Optional[List[float]] = None,
**kwargs,
):
"""
Calls the scheduler's `set_timesteps` method and retrieves timesteps from the scheduler after the call. Handles
custom timesteps. Any kwargs will be supplied to `scheduler.set_timesteps`.
Args:
scheduler (`SchedulerMixin`):
The scheduler to get timesteps from.
num_inference_steps (`int`):
The number of diffusion steps used when generating samples with a pre-trained model. If used, `timesteps`
must be `None`.
device (`str` or `torch.device`, *optional*):
The device to which the timesteps should be moved to. If `None`, the timesteps are not moved.
timesteps (`List[int]`, *optional*):
Custom timesteps used to override the timestep spacing strategy of the scheduler. If `timesteps` is passed,
`num_inference_steps` and `sigmas` must be `None`.
sigmas (`List[float]`, *optional*):
Custom sigmas used to override the timestep spacing strategy of the scheduler. If `sigmas` is passed,
`num_inference_steps` and `timesteps` must be `None`.
Returns:
`Tuple[torch.Tensor, int]`: A tuple where the first element is the timestep schedule from the scheduler and the
second element is the number of inference steps.
"""
if timesteps is not None and sigmas is not None:
raise ValueError(
"Only one of `timesteps` or `sigmas` can be passed. Please choose one to set custom values"
)
if timesteps is not None:
accepts_timesteps = "timesteps" in set(
inspect.signature(scheduler.set_timesteps).parameters.keys()
)
if not accepts_timesteps:
raise ValueError(
f"The current scheduler class {scheduler.__class__}'s `set_timesteps` does not support custom"
f" timestep schedules. Please check whether you are using the correct scheduler."
)
scheduler.set_timesteps(timesteps=timesteps, device=device, **kwargs)
timesteps = scheduler.timesteps
num_inference_steps = len(timesteps)
elif sigmas is not None:
accept_sigmas = "sigmas" in set(
inspect.signature(scheduler.set_timesteps).parameters.keys()
)
if not accept_sigmas:
raise ValueError(
f"The current scheduler class {scheduler.__class__}'s `set_timesteps` does not support custom"
f" sigmas schedules. Please check whether you are using the correct scheduler."
)
scheduler.set_timesteps(sigmas=sigmas, device=device, **kwargs)
timesteps = scheduler.timesteps
num_inference_steps = len(timesteps)
else:
scheduler.set_timesteps(num_inference_steps, device=device, **kwargs)
timesteps = scheduler.timesteps
return timesteps, num_inference_steps
class CustomPipeline(DiffusionPipeline, SD3LoraLoaderMixin):
r"""
The Flux pipeline for text-to-image generation.
Reference: https://blackforestlabs.ai/announcing-black-forest-labs/
Args:
transformer ([`FluxTransformer2DModelWithMasking`]):
Conditional Transformer (MMDiT) architecture to denoise the encoded image latents.
scheduler ([`FlowMatchEulerDiscreteScheduler`]):
A scheduler to be used in combination with `transformer` to denoise the encoded image latents.
vae ([`AutoencoderKL`]):
Variational Auto-Encoder (VAE) Model to encode and decode images to and from latent representations.
text_encoder ([`CLIPTextModelWithProjection`]):
[CLIP](https://huggingface.co/docs/transformers/model_doc/clip#transformers.CLIPTextModelWithProjection),
specifically the [clip-vit-large-patch14](https://huggingface.co/openai/clip-vit-large-patch14) variant,
with an additional added projection layer that is initialized with a diagonal matrix with the `hidden_size`
as its dimension.
text_encoder_2 ([`CLIPTextModelWithProjection`]):
[CLIP](https://huggingface.co/docs/transformers/model_doc/clip#transformers.CLIPTextModelWithProjection),
specifically the
[laion/CLIP-ViT-bigG-14-laion2B-39B-b160k](https://huggingface.co/laion/CLIP-ViT-bigG-14-laion2B-39B-b160k)
variant.
tokenizer (`CLIPTokenizer`):
Tokenizer of class
[CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer).
tokenizer_2 (`CLIPTokenizer`):
Second Tokenizer of class
[CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer).
"""
model_cpu_offload_seq = "text_encoder->text_encoder_2->transformer->vae"
_optional_components = []
_callback_tensor_inputs = ["latents", "prompt_embeds"]
def __init__(
self,
scheduler: FlowMatchEulerDiscreteScheduler,
vae: AutoencoderKL,
text_encoder: CLIPTextModel,
tokenizer: CLIPTokenizer,
text_encoder_2: T5EncoderModel,
tokenizer_2: T5TokenizerFast,
transformer: FluxTransformer2DModelWithMasking,
):
super().__init__()
self.register_modules(
vae=vae,
text_encoder=text_encoder,
text_encoder_2=text_encoder_2,
tokenizer=tokenizer,
tokenizer_2=tokenizer_2,
transformer=transformer,
scheduler=scheduler,
)
self.vae_scale_factor = (
2 ** (len(self.vae.config.block_out_channels))
if hasattr(self, "vae") and self.vae is not None
else 16
)
self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor)
self.tokenizer_max_length = (
self.tokenizer.model_max_length
if hasattr(self, "tokenizer") and self.tokenizer is not None
else 77
)
self.default_sample_size = 64
def _get_t5_prompt_embeds(
self,
prompt: Union[str, List[str]] = None,
num_images_per_prompt: int = 1,
max_sequence_length: int = 512,
device: Optional[torch.device] = None,
dtype: Optional[torch.dtype] = None,
):
device = device or self._execution_device
dtype = dtype or self.text_encoder.dtype
prompt = [prompt] if isinstance(prompt, str) else prompt
batch_size = len(prompt)
text_inputs = self.tokenizer_2(
prompt,
padding="max_length",
max_length=max_sequence_length,
truncation=True,
return_length=False,
return_overflowing_tokens=False,
return_tensors="pt",
)
prompt_attention_mask = text_inputs.attention_mask
text_input_ids = text_inputs.input_ids
untruncated_ids = self.tokenizer_2(
prompt, padding="longest", return_tensors="pt"
).input_ids
if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(text_input_ids, untruncated_ids):
removed_text = self.tokenizer_2.batch_decode(untruncated_ids[:, self.tokenizer_max_length - 1 : -1])
logger.warning(
"The following part of your input was truncated because `max_sequence_length` is set to "
f" {max_sequence_length} tokens: {removed_text}"
)
prompt_embeds = self.text_encoder_2(text_input_ids.to(device), output_hidden_states=False)[0]
dtype = self.text_encoder_2.dtype
prompt_embeds = prompt_embeds.to(dtype=dtype, device=device)
_, seq_len, _ = prompt_embeds.shape
# duplicate text embeddings and attention mask for each generation per prompt, using mps friendly method
prompt_embeds = prompt_embeds.repeat(1, num_images_per_prompt, 1)
prompt_embeds = prompt_embeds.view(batch_size * num_images_per_prompt, seq_len, -1)
return prompt_embeds, prompt_attention_mask
def _get_clip_prompt_embeds(
self,
prompt: Union[str, List[str]],
num_images_per_prompt: int = 1,
device: Optional[torch.device] = None,
):
device = device or self._execution_device
prompt = [prompt] if isinstance(prompt, str) else prompt
batch_size = len(prompt)
text_inputs = self.tokenizer(
prompt,
padding="max_length",
max_length=self.tokenizer_max_length,
truncation=True,
return_overflowing_tokens=False,
return_length=False,
return_tensors="pt",
)
text_input_ids = text_inputs.input_ids
untruncated_ids = self.tokenizer(
prompt, padding="longest", return_tensors="pt"
).input_ids
if untruncated_ids.shape[-1] >= text_input_ids.shape[-1] and not torch.equal(
text_input_ids, untruncated_ids
):
removed_text = self.tokenizer.batch_decode(
untruncated_ids[:, self.tokenizer_max_length - 1 : -1]
)
logger.warning(
"The following part of your input was truncated because CLIP can only handle sequences up to"
f" {self.tokenizer_max_length} tokens: {removed_text}"
)
prompt_embeds = self.text_encoder(
text_input_ids.to(device), output_hidden_states=False
)
# Use pooled output of CLIPTextModel
prompt_embeds = prompt_embeds.pooler_output
prompt_embeds = prompt_embeds.to(dtype=self.text_encoder.dtype, device=device)
# duplicate text embeddings for each generation per prompt, using mps friendly method
prompt_embeds = prompt_embeds.repeat(1, num_images_per_prompt, 1)
prompt_embeds = prompt_embeds.view(batch_size * num_images_per_prompt, -1)
return prompt_embeds
@lru_cache(maxsize=128)
def encode_prompt(
self,
prompt: Union[str, List[str]],
prompt_2: Union[str, List[str]],
device: Optional[torch.device] = None,
num_images_per_prompt: int = 1,
prompt_embeds: Optional[torch.FloatTensor] = None,
pooled_prompt_embeds: Optional[torch.FloatTensor] = None,
max_sequence_length: int = 512,
lora_scale: Optional[float] = None,
):
r"""
Args:
prompt (`str` or `List[str]`, *optional*):
prompt to be encoded
prompt_2 (`str` or `List[str]`, *optional*):
The prompt or prompts to be sent to the `tokenizer_2` and `text_encoder_2`. If not defined, `prompt` is
used in all text-encoders
device: (`torch.device`):
torch device
num_images_per_prompt (`int`):
number of images that should be generated per prompt
prompt_embeds (`torch.FloatTensor`, *optional*):
Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
provided, text embeddings will be generated from `prompt` input argument.
pooled_prompt_embeds (`torch.FloatTensor`, *optional*):
Pre-generated pooled text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting.
If not provided, pooled text embeddings will be generated from `prompt` input argument.
clip_skip (`int`, *optional*):
Number of layers to be skipped from CLIP while computing the prompt embeddings. A value of 1 means that
the output of the pre-final layer will be used for computing the prompt embeddings.
lora_scale (`float`, *optional*):
A lora scale that will be applied to all LoRA layers of the text encoder if LoRA layers are loaded.
"""
device = device or self._execution_device
# set lora scale so that monkey patched LoRA
# function of text encoder can correctly access it
if lora_scale is not None and isinstance(self, SD3LoraLoaderMixin):
self._lora_scale = lora_scale
# dynamically adjust the LoRA scale
if self.text_encoder is not None and USE_PEFT_BACKEND:
scale_lora_layers(self.text_encoder, lora_scale)
if self.text_encoder_2 is not None and USE_PEFT_BACKEND:
scale_lora_layers(self.text_encoder_2, lora_scale)
prompt = [prompt] if isinstance(prompt, str) else prompt
if prompt is not None:
batch_size = len(prompt)
else:
batch_size = prompt_embeds.shape[0]
prompt_attention_mask = None
if prompt_embeds is None:
prompt_2 = prompt_2 or prompt
prompt_2 = [prompt_2] if isinstance(prompt_2, str) else prompt_2
# We only use the pooled prompt output from the CLIPTextModel
pooled_prompt_embeds = self._get_clip_prompt_embeds(
prompt=prompt,
device=device,
num_images_per_prompt=num_images_per_prompt,
)
prompt_embeds, prompt_attention_mask = self._get_t5_prompt_embeds(
prompt=prompt_2,
num_images_per_prompt=num_images_per_prompt,
max_sequence_length=max_sequence_length,
device=device,
)
if self.text_encoder is not None:
if isinstance(self, SD3LoraLoaderMixin) and USE_PEFT_BACKEND:
# Retrieve the original scale by scaling back the LoRA layers
unscale_lora_layers(self.text_encoder, lora_scale)
if self.text_encoder_2 is not None:
if isinstance(self, SD3LoraLoaderMixin) and USE_PEFT_BACKEND:
# Retrieve the original scale by scaling back the LoRA layers
unscale_lora_layers(self.text_encoder_2, lora_scale)
dtype = self.text_encoder.dtype if self.text_encoder is not None else self.transformer.dtype
text_ids = torch.zeros(batch_size, prompt_embeds.shape[1], 3).to(device=device, dtype=dtype)
text_ids = text_ids.repeat(num_images_per_prompt, 1, 1)
return prompt_embeds, pooled_prompt_embeds, text_ids, prompt_attention_mask
def check_inputs(
self,
prompt,
prompt_2,
height,
width,
prompt_embeds=None,
pooled_prompt_embeds=None,
callback_on_step_end_tensor_inputs=None,
max_sequence_length=None,
):
if height % 8 != 0 or width % 8 != 0:
raise ValueError(
f"`height` and `width` have to be divisible by 8 but are {height} and {width}."
)
if callback_on_step_end_tensor_inputs is not None and not all(
k in self._callback_tensor_inputs
for k in callback_on_step_end_tensor_inputs
):
raise ValueError(
f"`callback_on_step_end_tensor_inputs` has to be in {self._callback_tensor_inputs}, but found {[k for k in callback_on_step_end_tensor_inputs if k not in self._callback_tensor_inputs]}"
)
if prompt is not None and prompt_embeds is not None:
raise ValueError(
f"Cannot forward both `prompt`: {prompt} and `prompt_embeds`: {prompt_embeds}. Please make sure to"
" only forward one of the two."
)
elif prompt_2 is not None and prompt_embeds is not None:
raise ValueError(
f"Cannot forward both `prompt_2`: {prompt_2} and `prompt_embeds`: {prompt_embeds}. Please make sure to"
" only forward one of the two."
)
elif prompt is None and prompt_embeds is None:
raise ValueError(
"Provide either `prompt` or `prompt_embeds`. Cannot leave both `prompt` and `prompt_embeds` undefined."
)
elif prompt is not None and (
not isinstance(prompt, str) and not isinstance(prompt, list)
):
raise ValueError(
f"`prompt` has to be of type `str` or `list` but is {type(prompt)}"
)
elif prompt_2 is not None and (
not isinstance(prompt_2, str) and not isinstance(prompt_2, list)
):
raise ValueError(
f"`prompt_2` has to be of type `str` or `list` but is {type(prompt_2)}"
)
if prompt_embeds is not None and pooled_prompt_embeds is None:
raise ValueError(
"If `prompt_embeds` are provided, `pooled_prompt_embeds` also have to be passed. Make sure to generate `pooled_prompt_embeds` from the same text encoder that was used to generate `prompt_embeds`."
)
if max_sequence_length is not None and max_sequence_length > 512:
raise ValueError(
f"`max_sequence_length` cannot be greater than 512 but is {max_sequence_length}"
)
@staticmethod
def _prepare_latent_image_ids(batch_size, height, width, device, dtype):
latent_image_ids = torch.zeros(height // 2, width // 2, 3)
latent_image_ids[..., 1] = (
latent_image_ids[..., 1] + torch.arange(height // 2)[:, None]
)
latent_image_ids[..., 2] = (
latent_image_ids[..., 2] + torch.arange(width // 2)[None, :]
)
latent_image_id_height, latent_image_id_width, latent_image_id_channels = (
latent_image_ids.shape
)
latent_image_ids = latent_image_ids[None, :].repeat(batch_size, 1, 1, 1)
latent_image_ids = latent_image_ids.reshape(
batch_size,
latent_image_id_height * latent_image_id_width,
latent_image_id_channels,
)
return latent_image_ids
@staticmethod
def _pack_latents(latents, batch_size, num_channels_latents, height, width):
latents = latents.view(
batch_size, num_channels_latents, height // 2, 2, width // 2, 2
)
latents = latents.permute(0, 2, 4, 1, 3, 5)
latents = latents.reshape(
batch_size, (height // 2) * (width // 2), num_channels_latents * 4
)
return latents
@staticmethod
def _unpack_latents(latents, height, width, vae_scale_factor):
batch_size, num_patches, channels = latents.shape
height = height // vae_scale_factor
width = width // vae_scale_factor
latents = latents.view(batch_size, height, width, channels // 4, 2, 2)
latents = latents.permute(0, 3, 1, 4, 2, 5)
latents = latents.reshape(
batch_size, channels // (2 * 2), height * 2, width * 2
)
return latents
def prepare_latents(
self,
batch_size,
num_channels_latents,
height,
width,
dtype,
device,
generator,
latents=None,
):
height = 2 * (int(height) // self.vae_scale_factor)
width = 2 * (int(width) // self.vae_scale_factor)
shape = (batch_size, num_channels_latents, height, width)
if latents is not None:
latent_image_ids = self._prepare_latent_image_ids(
batch_size, height, width, device, dtype
)
return latents, latent_image_ids
if isinstance(generator, list) and len(generator) != batch_size:
raise ValueError(
f"You have passed a list of generators of length {len(generator)}, but requested an effective batch"
f" size of {batch_size}. Make sure the batch size matches the length of the generators."
)
latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
latents = self._pack_latents(
latents, batch_size, num_channels_latents, height, width
)
latent_image_ids = self._prepare_latent_image_ids(
batch_size, height, width, device, dtype
)
return latents, latent_image_ids
@property
def guidance_scale(self):
return self._guidance_scale
@property
def joint_attention_kwargs(self):
return self._joint_attention_kwargs
@property
def num_timesteps(self):
return self._num_timesteps
@property
def interrupt(self):
return self._interrupt
@torch.no_grad()
@replace_example_docstring(EXAMPLE_DOC_STRING)
def __call__(
self,
prompt: Union[str, List[str]] = None,
prompt_mask: Optional[Union[torch.FloatTensor, List[torch.FloatTensor]]] = None,
negative_mask: Optional[
Union[torch.FloatTensor, List[torch.FloatTensor]]
] = None,
prompt_2: Optional[Union[str, List[str]]] = None,
height: Optional[int] = None,
width: Optional[int] = None,
num_inference_steps: int = 28,
timesteps: List[int] = None,
guidance_scale: float = 3.5,
num_images_per_prompt: Optional[int] = 1,
generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
latents: Optional[torch.FloatTensor] = None,
prompt_embeds: Optional[torch.FloatTensor] = None,
pooled_prompt_embeds: Optional[torch.FloatTensor] = None,
output_type: Optional[str] = "pil",
return_dict: bool = True,
joint_attention_kwargs: Optional[Dict[str, Any]] = None,
callback_on_step_end: Optional[Callable[[int, int, Dict], None]] = None,
callback_on_step_end_tensor_inputs: List[str] = ["latents"],
max_sequence_length: int = 512,
guidance_scale_real: float = 1.0,
negative_prompt: Union[str, List[str]] = "",
negative_prompt_2: Union[str, List[str]] = "",
negative_prompt_embeds: Optional[torch.FloatTensor] = None,
negative_pooled_prompt_embeds: Optional[torch.FloatTensor] = None,
no_cfg_until_timestep: int = 0,
do_batch_cfg: bool=True,
device=torch.device('cuda'), # TODO let this work with non-cuda stuff? Might if you set this to None
):
r"""
Function invoked when calling the pipeline for generation.
Args:
prompt (`str` or `List[str]`, *optional*):
The prompt or prompts to guide the image generation. If not defined, one has to pass `prompt_embeds`.
instead.
prompt_mask (`str` or `List[str]`, *optional*):
The prompt or prompts to be used as a mask for the image generation. If not defined, `prompt` is used
instead.
prompt_2 (`str` or `List[str]`, *optional*):
The prompt or prompts to be sent to `tokenizer_2` and `text_encoder_2`. If not defined, `prompt` is
will be used instead
height (`int`, *optional*, defaults to self.unet.config.sample_size * self.vae_scale_factor):
The height in pixels of the generated image. This is set to 1024 by default for the best results.
width (`int`, *optional*, defaults to self.unet.config.sample_size * self.vae_scale_factor):
The width in pixels of the generated image. This is set to 1024 by default for the best results.
num_inference_steps (`int`, *optional*, defaults to 50):
The number of denoising steps. More denoising steps usually lead to a higher quality image at the
expense of slower inference.
timesteps (`List[int]`, *optional*):
Custom timesteps to use for the denoising process with schedulers which support a `timesteps` argument
in their `set_timesteps` method. If not defined, the default behavior when `num_inference_steps` is
passed will be used. Must be in descending order.
guidance_scale (`float`, *optional*, defaults to 7.0):
Guidance scale as defined in [Classifier-Free Diffusion Guidance](https://arxiv.org/abs/2207.12598).
`guidance_scale` is defined as `w` of equation 2. of [Imagen
Paper](https://arxiv.org/pdf/2205.11487.pdf). Guidance scale is enabled by setting `guidance_scale >
1`. Higher guidance scale encourages to generate images that are closely linked to the text `prompt`,
usually at the expense of lower image quality.
num_images_per_prompt (`int`, *optional*, defaults to 1):
The number of images to generate per prompt.
generator (`torch.Generator` or `List[torch.Generator]`, *optional*):
One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html)
to make generation deterministic.
latents (`torch.FloatTensor`, *optional*):
Pre-generated noisy latents, sampled from a Gaussian distribution, to be used as inputs for image
generation. Can be used to tweak the same generation with different prompts. If not provided, a latents
tensor will ge generated by sampling using the supplied random `generator`.
prompt_embeds (`torch.FloatTensor`, *optional*):
Pre-generated text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting. If not
provided, text embeddings will be generated from `prompt` input argument.
pooled_prompt_embeds (`torch.FloatTensor`, *optional*):
Pre-generated pooled text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt weighting.
If not provided, pooled text embeddings will be generated from `prompt` input argument.
output_type (`str`, *optional*, defaults to `"pil"`):
The output format of the generate image. Choose between
[PIL](https://pillow.readthedocs.io/en/stable/): `PIL.Image.Image` or `np.array`.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`~pipelines.flux.FluxPipelineOutput`] instead of a plain tuple.
joint_attention_kwargs (`dict`, *optional*):
A kwargs dictionary that if specified is passed along to the `AttentionProcessor` as defined under
`self.processor` in
[diffusers.models.attention_processor](https://github.com/huggingface/diffusers/blob/main/src/diffusers/models/attention_processor.py).
callback_on_step_end (`Callable`, *optional*):
A function that calls at the end of each denoising steps during the inference. The function is called
with the following arguments: `callback_on_step_end(self: DiffusionPipeline, step: int, timestep: int,
callback_kwargs: Dict)`. `callback_kwargs` will include a list of all tensors as specified by
`callback_on_step_end_tensor_inputs`.
callback_on_step_end_tensor_inputs (`List`, *optional*):
The list of tensor inputs for the `callback_on_step_end` function. The tensors specified in the list
will be passed as `callback_kwargs` argument. You will only be able to include variables listed in the
`._callback_tensor_inputs` attribute of your pipeline class.
max_sequence_length (`int` defaults to 512): Maximum sequence length to use with the `prompt`.
Examples:
Returns:
[`~pipelines.flux.FluxPipelineOutput`] or `tuple`: [`~pipelines.flux.FluxPipelineOutput`] if `return_dict`
is True, otherwise a `tuple`. When returning a tuple, the first element is a list with the generated
images.
"""
height = height or self.default_sample_size * self.vae_scale_factor
width = width or self.default_sample_size * self.vae_scale_factor
# 1. Check inputs. Raise error if not correct
self.check_inputs(
prompt,
prompt_2,
height,
width,
prompt_embeds=prompt_embeds,
pooled_prompt_embeds=pooled_prompt_embeds,
callback_on_step_end_tensor_inputs=callback_on_step_end_tensor_inputs,
max_sequence_length=max_sequence_length,
)
# guidance_scale_real is redundant because this pipeline was originally
# made to be backwards compatible, but to make it the default just set
# guidance scale to be the same things.
guidance_scale_real = guidance_scale
self._guidance_scale = guidance_scale
self._guidance_scale_real = guidance_scale_real
self._joint_attention_kwargs = joint_attention_kwargs
self._interrupt = False
# 2. Define call parameters
if prompt is not None and isinstance(prompt, str):
batch_size = 1
elif prompt is not None and isinstance(prompt, list):
batch_size = len(prompt)
else:
batch_size = prompt_embeds.shape[0]
device = device or self._execution_device
lora_scale = (
self.joint_attention_kwargs.get("scale", None)
if self.joint_attention_kwargs is not None
else None
)
(
prompt_embeds,
pooled_prompt_embeds,
text_ids,
_prompt_mask,
) = self.encode_prompt(
prompt=prompt,
prompt_2=prompt_2,
prompt_embeds=prompt_embeds,
pooled_prompt_embeds=pooled_prompt_embeds,
device=device,
num_images_per_prompt=num_images_per_prompt,
max_sequence_length=max_sequence_length,
lora_scale=lora_scale,
)
if _prompt_mask is not None:
prompt_mask = _prompt_mask
assert prompt_mask is not None
if negative_prompt_2 == "" and negative_prompt != "":
negative_prompt_2 = negative_prompt
negative_text_ids = text_ids
if self._guidance_scale_real > 1.0 and (
negative_prompt_embeds is None or negative_pooled_prompt_embeds is None
):
(
negative_prompt_embeds,
negative_pooled_prompt_embeds,
negative_text_ids,
_neg_prompt_mask,
) = self.encode_prompt(
prompt=negative_prompt,
prompt_2=negative_prompt_2,
prompt_embeds=None,
pooled_prompt_embeds=None,
device=device,
num_images_per_prompt=num_images_per_prompt,
max_sequence_length=max_sequence_length,
lora_scale=lora_scale,
)
if _neg_prompt_mask is not None:
negative_mask = _neg_prompt_mask
assert negative_mask is not None
# 4. Prepare latent variables
num_channels_latents = self.transformer.config.in_channels // 4
latents, latent_image_ids = self.prepare_latents(
batch_size * num_images_per_prompt,
num_channels_latents,
height,
width,
prompt_embeds.dtype,
device,
generator,
latents,
)
# 5. Prepare timesteps
sigmas = np.linspace(1.0, 1 / num_inference_steps, num_inference_steps)
image_seq_len = latents.shape[1]
mu = calculate_shift(
image_seq_len,
self.scheduler.config.base_image_seq_len,
self.scheduler.config.max_image_seq_len,
self.scheduler.config.base_shift,
self.scheduler.config.max_shift,
)
timesteps, num_inference_steps = retrieve_timesteps(
self.scheduler,
num_inference_steps,
device,
timesteps,
sigmas,
mu=mu,
)
num_warmup_steps = max(
len(timesteps) - num_inference_steps * self.scheduler.order, 0
)
self._num_timesteps = len(timesteps)
latents = latents
latent_image_ids = latent_image_ids
timesteps = timesteps
text_ids = text_ids.to(device=device)
# handle guidance
if self.transformer.config.guidance_embeds:
guidance = torch.full([1], guidance_scale, device=device, dtype=torch.float32)
guidance = guidance.expand(latents.shape[0])
else:
guidance = None
# if use_prompt_mask and prompt_mask is not None and not zero_using_prompt_mask:
# print('Using masking')
# elif use_prompt_mask and prompt_mask is not None and zero_using_prompt_mask:
# print('Using zeroed embeds')
# else:
# print('Not using masking')
# if self._guidance_scale_real > 1.0:
# print('Using classifier free guidance', self._guidance_scale_real)
# 6. Denoising loop
with self.progress_bar(total=num_inference_steps) as progress_bar:
for i, t in enumerate(timesteps):
if self.interrupt:
continue
# Prepare the latent model input
prompt_embeds_input = prompt_embeds
pooled_prompt_embeds_input = pooled_prompt_embeds
text_ids_input = text_ids
latent_image_ids_input = latent_image_ids
prompt_mask_input = prompt_mask
latent_model_input = latents
if guidance_scale_real > 1.0 and i >= no_cfg_until_timestep:
progress_bar.set_postfix(
{
'ts': t.detach().item() / 1000.0,
'cfg': self._guidance_scale_real,
},
)
else:
progress_bar.set_postfix(
{
'ts': t.detach().item() / 1000.0,
'cfg': 'N/A',
},
)
if do_batch_cfg and guidance_scale_real > 1.0 and i >= no_cfg_until_timestep:
# Concatenate prompt embeddings
prompt_embeds_input = torch.cat([negative_prompt_embeds, prompt_embeds], dim=0)
pooled_prompt_embeds_input = torch.cat([negative_pooled_prompt_embeds, pooled_prompt_embeds], dim=0)
# Concatenate text IDs if they are used
# if text_ids is not None and negative_text_ids is not None:
# text_ids_input = torch.cat([negative_text_ids, text_ids], dim=0)
# Concatenate latent image IDs if they are used
# if latent_image_ids is not None:
# latent_image_ids_input = torch.cat([latent_image_ids, latent_image_ids], dim=0)
# Concatenate prompt masks if they are used
if prompt_mask is not None and negative_mask is not None:
prompt_mask_input = torch.cat([negative_mask, prompt_mask], dim=0)
# Duplicate latents for unconditional and conditional inputs
latent_model_input = torch.cat([latents] * 2)
# Expand timestep to match batch size
timestep = t.expand(latent_model_input.shape[0]).to(latents.dtype)
# Handle guidance
if self.transformer.config.guidance_embeds:
guidance = torch.tensor([guidance_scale], device=self.transformer.device)
guidance = guidance.expand(latent_model_input.shape[0])
else:
guidance = None
# Prepare extra transformer arguments
extra_transformer_args = {}
if prompt_mask is not None:
extra_transformer_args["attention_mask"] = prompt_mask_input.to(device=self.transformer.device)
# Forward pass through the transformer
noise_pred = self.transformer(
hidden_states=latent_model_input.to(device=self.transformer.device),
timestep=timestep / 1000,
guidance=guidance,
pooled_projections=pooled_prompt_embeds_input.to(device=self.transformer.device),
encoder_hidden_states=prompt_embeds_input.to(device=self.transformer.device),
txt_ids=text_ids_input.to(device=self.transformer.device) if text_ids is not None else None,
img_ids=latent_image_ids_input.to(device=self.transformer.device) if latent_image_ids is not None else None,
joint_attention_kwargs=self.joint_attention_kwargs,
return_dict=False,
**extra_transformer_args,
)[0]
# Apply real CFG
if guidance_scale_real > 1.0 and i >= no_cfg_until_timestep:
if do_batch_cfg:
# Batched CFG: Split the noise prediction into unconditional and conditional parts
noise_pred_uncond, noise_pred_cond = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + guidance_scale_real * (noise_pred_cond - noise_pred_uncond)
else:
# Sequential CFG: Compute unconditional noise prediction separately
noise_pred_uncond = self.transformer(
hidden_states=latents.to(device=self.transformer.device),
timestep=timestep / 1000,
guidance=guidance,
pooled_projections=negative_pooled_prompt_embeds.to(device=self.transformer.device),
encoder_hidden_states=negative_prompt_embeds.to(device=self.transformer.device),
txt_ids=negative_text_ids.to(device=self.transformer.device) if negative_text_ids is not None else None,
img_ids=latent_image_ids.to(device=self.transformer.device) if latent_image_ids is not None else None,
joint_attention_kwargs=self.joint_attention_kwargs,
return_dict=False,
)[0]
# Combine conditional and unconditional predictions
noise_pred = noise_pred_uncond + guidance_scale_real * (noise_pred - noise_pred_uncond)
# Compute the previous noisy sample x_t -> x_t-1
latents_dtype = latents.dtype
latents = self.scheduler.step(noise_pred, t, latents, return_dict=False)[0]
# Ensure latents have the correct dtype
if latents.dtype != latents_dtype:
if torch.backends.mps.is_available():
latents = latents.to(latents_dtype)
# Callback at the end of the step, if provided
if callback_on_step_end is not None:
callback_kwargs = {k: locals()[k] for k in callback_on_step_end_tensor_inputs}
callback_outputs = callback_on_step_end(self, i, t, callback_kwargs)
latents = callback_outputs.get("latents", latents)
prompt_embeds = callback_outputs.get("prompt_embeds", prompt_embeds)
# Update the progress bar
if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0):
progress_bar.update()
# Mark step for XLA devices
if XLA_AVAILABLE:
xm.mark_step()
if output_type == "latent":
image = latents
else:
latents = self._unpack_latents(
latents, height, width, self.vae_scale_factor
)
latents = (
latents / self.vae.config.scaling_factor
) + self.vae.config.shift_factor
image = self.vae.decode(
latents,
return_dict=False,
)[0]
image = self.image_processor.postprocess(image, output_type=output_type)
# Offload all models
self.maybe_free_model_hooks()
if not return_dict:
return (image,)
return FluxPipelineOutput(images=image)