VisCPM-Paint / pipeline.py
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# Copyright 2023 The HuggingFace Team. All rights reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import inspect
import warnings
from typing import Any, Callable, Dict, List, Optional, Union, Tuple
import numpy as np
import torch
from torch.utils.data.dataloader import default_collate
from packaging import version
from transformers import CLIPImageProcessor, CLIPTextModel, CLIPTokenizer
from diffusers.configuration_utils import FrozenDict
from diffusers.image_processor import VaeImageProcessor
from diffusers.loaders import FromSingleFileMixin, LoraLoaderMixin, TextualInversionLoaderMixin
from diffusers.models import AutoencoderKL, UNet2DConditionModel
from diffusers.schedulers import KarrasDiffusionSchedulers
from diffusers.utils import (
deprecate,
is_accelerate_available,
is_accelerate_version,
logging,
randn_tensor,
replace_example_docstring,
)
from diffusers.pipeline_utils import DiffusionPipeline
from diffusers.pipelines.stable_diffusion.safety_checker import StableDiffusionSafetyChecker
from diffusers.pipelines.stable_diffusion import StableDiffusionPipelineOutput
from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion import rescale_noise_cfg, StableDiffusionPipeline
from .modeling_cpmbee import CpmBeeModel
from .tokenization_viscpmbee import VisCpmBeeTokenizer
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
def pad(orig_items, key, max_length=None, padding_value=0, padding_side="left"):
items = []
if isinstance(orig_items[0][key], list):
assert isinstance(orig_items[0][key][0], torch.Tensor)
for it in orig_items:
for tr in it[key]:
items.append({key: tr})
else:
assert isinstance(orig_items[0][key], torch.Tensor)
items = orig_items
batch_size = len(items)
shape = items[0][key].shape
dim = len(shape)
assert dim <= 3
if max_length is None:
max_length = 0
max_length = max(max_length, max(item[key].shape[-1] for item in items))
min_length = min(item[key].shape[-1] for item in items)
dtype = items[0][key].dtype
if dim == 1:
return torch.cat([item[key] for item in items], dim=0)
elif dim == 2:
if max_length == min_length:
return torch.cat([item[key] for item in items], dim=0)
tensor = torch.zeros((batch_size, max_length), dtype=dtype) + padding_value
else:
tensor = torch.zeros((batch_size, max_length, shape[-1]), dtype=dtype) + padding_value
for i, item in enumerate(items):
if dim == 2:
if padding_side == "left":
tensor[i, -len(item[key][0]):] = item[key][0].clone()
else:
tensor[i, : len(item[key][0])] = item[key][0].clone()
elif dim == 3:
if padding_side == "left":
tensor[i, -len(item[key][0]):, :] = item[key][0].clone()
else:
tensor[i, : len(item[key][0]), :] = item[key][0].clone()
return tensor
class CPMBeeCollater:
"""
针对 cpmbee 输入数据 collate, 对应 cpm-live 的 _MixedDatasetBatchPacker
目前利用 torch 的原生 Dataloader 不太适合改造 in-context-learning
并且原来实现为了最大化提高有效 token 比比例, 会有一个 best_fit 操作, 这个目前也不支持
todo: 重写一下 Dataloader or BatchPacker
"""
def __init__(self, tokenizer: VisCpmBeeTokenizer, max_len):
self.tokenizer = tokenizer
self._max_length = max_len
self.pad_keys = ['input_ids', 'input_id_subs', 'context', 'segment_ids', 'segment_rel_offset',
'segment_rel', 'sample_ids', 'num_segments']
def __call__(self, batch):
batch_size = len(batch)
tgt = np.full((batch_size, self._max_length), -100, dtype=np.int32)
# 目前没有 best_fit, span 为全 0
span = np.zeros((batch_size, self._max_length), dtype=np.int32)
length = np.zeros((batch_size,), dtype=np.int32)
batch_ext_table_map: Dict[Tuple[int, int], int] = {}
batch_ext_table_ids: List[int] = []
batch_ext_table_sub: List[int] = []
raw_data_list: List[Any] = []
for i in range(batch_size):
instance_length = batch[i]['input_ids'][0].shape[0]
length[i] = instance_length
raw_data_list.extend(batch[i]['raw_data'])
for j in range(instance_length):
idx, idx_sub = batch[i]['input_ids'][0, j], batch[i]['input_id_subs'][0, j]
tgt_idx = idx
if idx_sub > 0:
# need to be in ext table
if (idx, idx_sub) not in batch_ext_table_map:
batch_ext_table_map[(idx, idx_sub)] = len(batch_ext_table_map)
batch_ext_table_ids.append(idx)
batch_ext_table_sub.append(idx_sub)
tgt_idx = batch_ext_table_map[(idx, idx_sub)] + self.tokenizer.vocab_size
if j > 1 and batch[i]['context'][0, j - 1] == 0:
if idx != self.tokenizer.bos_id:
tgt[i, j - 1] = tgt_idx
else:
tgt[i, j - 1] = self.tokenizer.eos_id
if batch[i]['context'][0, instance_length - 1] == 0:
tgt[i, instance_length - 1] = self.tokenizer.eos_id
if len(batch_ext_table_map) == 0:
# placeholder
batch_ext_table_ids.append(0)
batch_ext_table_sub.append(1)
# image
if 'pixel_values' in batch[0]:
data = {'pixel_values': default_collate([i['pixel_values'] for i in batch])}
else:
data = {}
# image_bound
if 'image_bound' in batch[0]:
data['image_bound'] = default_collate([i['image_bound'] for i in batch])
# bee inp
for key in self.pad_keys:
data[key] = pad(batch, key, max_length=self._max_length, padding_value=0, padding_side='right')
data['context'] = data['context'] > 0
data['length'] = torch.from_numpy(length)
data['span'] = torch.from_numpy(span)
data['target'] = torch.from_numpy(tgt)
data['ext_table_ids'] = torch.from_numpy(np.array(batch_ext_table_ids))
data['ext_table_sub'] = torch.from_numpy(np.array(batch_ext_table_sub))
data['raw_data'] = raw_data_list
return data
class VisCPMPaintBeePipeline(StableDiffusionPipeline):
_optional_components = ["safety_checker", "feature_extractor"]
def __init__(
self,
vae: AutoencoderKL,
text_encoder: CpmBeeModel,
tokenizer: VisCpmBeeTokenizer,
unet: UNet2DConditionModel,
scheduler: KarrasDiffusionSchedulers,
safety_checker: StableDiffusionSafetyChecker,
feature_extractor: CLIPImageProcessor,
requires_safety_checker: bool = True,
):
super().__init__(
vae=vae,
text_encoder=text_encoder,
tokenizer=tokenizer,
unet=unet,
scheduler=scheduler,
safety_checker=safety_checker,
feature_extractor=feature_extractor,
requires_safety_checker=requires_safety_checker
)
def build_input(
self,
prompt: str,
negative_prompt: Optional[str] = None,
image_size: int = 512
):
data_input = {'caption': prompt, 'objects': ''}
(
input_ids,
input_id_subs,
context,
segment_ids,
segment_rel,
n_segments,
table_states,
image_bound
) = self.tokenizer.convert_data_to_id(data=data_input, shuffle_answer=False, max_depth=8)
sample_ids = np.zeros(input_ids.shape, dtype=np.int32)
segment_rel_offset = np.zeros(input_ids.shape, dtype=np.int32)
num_segments = np.full(input_ids.shape, n_segments, dtype=np.int32)
data = {
'pixel_values': torch.zeros(3, image_size, image_size).unsqueeze(0),
'input_ids': torch.from_numpy(input_ids).unsqueeze(0),
'input_id_subs': torch.from_numpy(input_id_subs).unsqueeze(0),
'context': torch.from_numpy(context).unsqueeze(0),
'segment_ids': torch.from_numpy(segment_ids).unsqueeze(0),
'segment_rel_offset': torch.from_numpy(segment_rel_offset).unsqueeze(0),
'segment_rel': torch.from_numpy(segment_rel).unsqueeze(0),
'sample_ids': torch.from_numpy(sample_ids).unsqueeze(0),
'num_segments': torch.from_numpy(num_segments).unsqueeze(0),
'image_bound': image_bound,
'raw_data': prompt,
}
uncond_data_input = {
'caption': "" if negative_prompt is None else negative_prompt,
'objects': ''
}
(
input_ids,
input_id_subs,
context,
segment_ids,
segment_rel,
n_segments,
table_states,
image_bound
) = self.tokenizer.convert_data_to_id(data=uncond_data_input, shuffle_answer=False, max_depth=8)
sample_ids = np.zeros(input_ids.shape, dtype=np.int32)
segment_rel_offset = np.zeros(input_ids.shape, dtype=np.int32)
num_segments = np.full(input_ids.shape, n_segments, dtype=np.int32)
uncond_data = {
'pixel_values': torch.zeros(3, image_size, image_size).unsqueeze(0),
'input_ids': torch.from_numpy(input_ids).unsqueeze(0),
'input_id_subs': torch.from_numpy(input_id_subs).unsqueeze(0),
'context': torch.from_numpy(context).unsqueeze(0),
'segment_ids': torch.from_numpy(segment_ids).unsqueeze(0),
'segment_rel_offset': torch.from_numpy(segment_rel_offset).unsqueeze(0),
'segment_rel': torch.from_numpy(segment_rel).unsqueeze(0),
'sample_ids': torch.from_numpy(sample_ids).unsqueeze(0),
'num_segments': torch.from_numpy(num_segments).unsqueeze(0),
'image_bound': image_bound,
'raw_data': "" if negative_prompt is None else negative_prompt,
}
packer = CPMBeeCollater(
tokenizer=self.tokenizer,
max_len=max(data['input_ids'].size(-1), uncond_data['input_ids'].size(-1))
)
data = packer([data])
uncond_data = packer([uncond_data])
return data, uncond_data
def _encode_prompt(
self,
prompt,
device,
num_images_per_prompt,
do_classifier_free_guidance,
negative_prompt=None,
prompt_embeds: Optional[torch.FloatTensor] = None,
negative_prompt_embeds: Optional[torch.FloatTensor] = None,
lora_scale: Optional[float] = None,
):
r"""
Encodes the prompt into text encoder hidden states.
Args:
prompt (`str` or `List[str]`, *optional*):
prompt to be encoded
device: (`torch.device`):
torch device
num_images_per_prompt (`int`):
number of images that should be generated per prompt
do_classifier_free_guidance (`bool`):
whether to use classifier free guidance or not
negative_prompt (`str` or `List[str]`, *optional*):
The prompt or prompts not to guide the image generation. If not defined, one has to pass
`negative_prompt_embeds` instead. Ignored when not using guidance (i.e., ignored if `guidance_scale` is
less than `1`).
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.
negative_prompt_embeds (`torch.FloatTensor`, *optional*):
Pre-generated negative text embeddings. Can be used to easily tweak text inputs, *e.g.* prompt
weighting. If not provided, negative_prompt_embeds will be generated from `negative_prompt` input
argument.
lora_scale (`float`, *optional*):
A lora scale that will be applied to all LoRA layers of the text encoder if LoRA layers are loaded.
"""
# 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, LoraLoaderMixin):
self._lora_scale = lora_scale
data, uncond_data = self.build_input(prompt, negative_prompt, image_size=512)
for key, value in data.items():
if isinstance(value, torch.Tensor):
data[key] = value.to(self.device)
for key, value in uncond_data.items():
if isinstance(value, torch.Tensor):
uncond_data[key] = value.to(self.device)
batch, seq_length = data['input_ids'].size()
dtype, device = data['input_ids'].dtype, data['input_ids'].device
data['position'] = torch.arange(seq_length, dtype=dtype, device=device).repeat(batch, 1)
batch, seq_length = uncond_data['input_ids'].size()
dtype, device = uncond_data['input_ids'].dtype, uncond_data['input_ids'].device
uncond_data['position'] = torch.arange(seq_length, dtype=dtype, device=device).repeat(batch, 1)
with torch.no_grad():
# llm_hidden_state = self.text_encoder.llm.input_embedding(data['input_ids'], data['input_id_subs'])
_, hidden_states = self.text_encoder(
input_ids=data['input_ids'],
input_id_sub=data['input_id_subs'],
position=data['position'],
#length=data['length'],
context=data['context'],
sample_ids=data['sample_ids'],
num_segments=data['num_segments'],
segment=data['segment_ids'],
segment_rel_offset=data['segment_rel_offset'],
segment_rel=data['segment_rel'],
#span=data['span'],
#ext_table_ids=data['ext_table_ids'],
#ext_table_sub=data['ext_table_sub'],
#hidden_states=llm_hidden_state
)
with torch.no_grad():
# uncond_llm_hidden_state = self.text_encoder.llm.input_embedding(uncond_data['input_ids'], uncond_data['input_id_subs'])
_, uncond_hidden_states = self.text_encoder(
input_ids=uncond_data['input_ids'],
input_id_sub=uncond_data['input_id_subs'],
position=uncond_data['position'],
#length=uncond_data['length'],
context=uncond_data['context'],
sample_ids=uncond_data['sample_ids'],
num_segments=uncond_data['num_segments'],
segment=uncond_data['segment_ids'],
segment_rel_offset=uncond_data['segment_rel_offset'],
segment_rel=uncond_data['segment_rel'],
#span=uncond_data['span'],
#ext_table_ids=uncond_data['ext_table_ids'],
#ext_table_sub=uncond_data['ext_table_sub'],
#hidden_states=uncond_llm_hidden_state
)
text_hidden_states, uncond_text_hidden_states = hidden_states, uncond_hidden_states
if self.text_encoder.trans_block is not None:
text_hidden_states = self.text_encoder.trans_block(text_hidden_states)
uncond_text_hidden_states = self.text_encoder.trans_block(uncond_text_hidden_states)
bs_embed, seq_len, _ = text_hidden_states.shape
text_hidden_states = text_hidden_states.repeat(1, num_images_per_prompt, 1)
text_hidden_states = text_hidden_states.view(bs_embed * num_images_per_prompt, seq_len, -1)
bs_embed, seq_len, _ = uncond_text_hidden_states.shape
uncond_text_hidden_states = uncond_text_hidden_states.repeat(1, num_images_per_prompt, 1)
uncond_text_hidden_states = uncond_text_hidden_states.view(bs_embed * num_images_per_prompt, seq_len, -1)
prompt_embeds = torch.cat([uncond_text_hidden_states, text_hidden_states])
return prompt_embeds
# 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]
# if prompt_embeds is None:
# # textual inversion: procecss multi-vector tokens if necessary
# if isinstance(self, TextualInversionLoaderMixin):
# prompt = self.maybe_convert_prompt(prompt, self.tokenizer)
# text_inputs = self.tokenizer(
# prompt,
# padding="max_length",
# max_length=self.tokenizer.model_max_length,
# truncation=True,
# 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.model_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.model_max_length} tokens: {removed_text}"
# )
# if hasattr(self.text_encoder.config, "use_attention_mask") and self.text_encoder.config.use_attention_mask:
# attention_mask = text_inputs.attention_mask.to(device)
# else:
# attention_mask = None
# prompt_embeds = self.text_encoder(
# text_input_ids.to(device),
# attention_mask=attention_mask,
# )
# prompt_embeds = prompt_embeds[0]
# prompt_embeds = prompt_embeds.to(dtype=self.text_encoder.dtype, device=device)
# bs_embed, seq_len, _ = prompt_embeds.shape
# # 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(bs_embed * num_images_per_prompt, seq_len, -1)
# # get unconditional embeddings for classifier free guidance
# if do_classifier_free_guidance and negative_prompt_embeds is None:
# uncond_tokens: List[str]
# if negative_prompt is None:
# uncond_tokens = [""] * batch_size
# elif prompt is not None and type(prompt) is not type(negative_prompt):
# raise TypeError(
# f"`negative_prompt` should be the same type to `prompt`, but got {type(negative_prompt)} !="
# f" {type(prompt)}."
# )
# elif isinstance(negative_prompt, str):
# uncond_tokens = [negative_prompt]
# elif batch_size != len(negative_prompt):
# raise ValueError(
# f"`negative_prompt`: {negative_prompt} has batch size {len(negative_prompt)}, but `prompt`:"
# f" {prompt} has batch size {batch_size}. Please make sure that passed `negative_prompt` matches"
# " the batch size of `prompt`."
# )
# else:
# uncond_tokens = negative_prompt
# # textual inversion: procecss multi-vector tokens if necessary
# if isinstance(self, TextualInversionLoaderMixin):
# uncond_tokens = self.maybe_convert_prompt(uncond_tokens, self.tokenizer)
# max_length = prompt_embeds.shape[1]
# uncond_input = self.tokenizer(
# uncond_tokens,
# padding="max_length",
# max_length=max_length,
# truncation=True,
# return_tensors="pt",
# )
# if hasattr(self.text_encoder.config, "use_attention_mask") and self.text_encoder.config.use_attention_mask:
# attention_mask = uncond_input.attention_mask.to(device)
# else:
# attention_mask = None
# negative_prompt_embeds = self.text_encoder(
# uncond_input.input_ids.to(device),
# attention_mask=attention_mask,
# )
# negative_prompt_embeds = negative_prompt_embeds[0]
# if do_classifier_free_guidance:
# # duplicate unconditional embeddings for each generation per prompt, using mps friendly method
# seq_len = negative_prompt_embeds.shape[1]
# negative_prompt_embeds = negative_prompt_embeds.to(dtype=self.text_encoder.dtype, device=device)
# negative_prompt_embeds = negative_prompt_embeds.repeat(1, num_images_per_prompt, 1)
# negative_prompt_embeds = negative_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len, -1)
# # For classifier free guidance, we need to do two forward passes.
# # Here we concatenate the unconditional and text embeddings into a single batch
# # to avoid doing two forward passes
# prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
# return prompt_embeds
def decode_latents(self, latents):
warnings.warn(
"The decode_latents method is deprecated and will be removed in a future version. Please"
" use VaeImageProcessor instead",
FutureWarning,
)
latents = 1 / self.vae.config.scaling_factor * latents
image = self.vae.decode(latents, return_dict=False)[0]
image = (image / 2 + 0.5).clamp(0, 1)
# we always cast to float32 as this does not cause significant overhead and is compatible with bfloat16
image = image.cpu().permute(0, 2, 3, 1).float().numpy()
return image
def prepare_extra_step_kwargs(self, generator, eta):
# prepare extra kwargs for the scheduler step, since not all schedulers have the same signature
# eta (η) is only used with the DDIMScheduler, it will be ignored for other schedulers.
# eta corresponds to η in DDIM paper: https://arxiv.org/abs/2010.02502
# and should be between [0, 1]
accepts_eta = "eta" in set(inspect.signature(self.scheduler.step).parameters.keys())
extra_step_kwargs = {}
if accepts_eta:
extra_step_kwargs["eta"] = eta
# check if the scheduler accepts generator
accepts_generator = "generator" in set(inspect.signature(self.scheduler.step).parameters.keys())
if accepts_generator:
extra_step_kwargs["generator"] = generator
return extra_step_kwargs
def check_inputs(
self,
prompt,
height,
width,
callback_steps,
negative_prompt=None,
prompt_embeds=None,
negative_prompt_embeds=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_steps is None) or (
callback_steps is not None and (not isinstance(callback_steps, int) or callback_steps <= 0)
):
raise ValueError(
f"`callback_steps` has to be a positive integer but is {callback_steps} of type"
f" {type(callback_steps)}."
)
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 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)}")
if negative_prompt is not None and negative_prompt_embeds is not None:
raise ValueError(
f"Cannot forward both `negative_prompt`: {negative_prompt} and `negative_prompt_embeds`:"
f" {negative_prompt_embeds}. Please make sure to only forward one of the two."
)
if prompt_embeds is not None and negative_prompt_embeds is not None:
if prompt_embeds.shape != negative_prompt_embeds.shape:
raise ValueError(
"`prompt_embeds` and `negative_prompt_embeds` must have the same shape when passed directly, but"
f" got: `prompt_embeds` {prompt_embeds.shape} != `negative_prompt_embeds`"
f" {negative_prompt_embeds.shape}."
)
def prepare_latents(self, batch_size, num_channels_latents, height, width, dtype, device, generator, latents=None):
shape = (batch_size, num_channels_latents, height // self.vae_scale_factor, width // self.vae_scale_factor)
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."
)
if latents is None:
latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
else:
latents = latents.to(device)
# scale the initial noise by the standard deviation required by the scheduler
latents = latents * self.scheduler.init_noise_sigma
return latents
@torch.no_grad()
def __call__(
self,
prompt: Union[str, List[str]] = None,
height: Optional[int] = None,
width: Optional[int] = None,
num_inference_steps: int = 50,
guidance_scale: float = 7.5,
negative_prompt: Optional[Union[str, List[str]]] = None,
num_images_per_prompt: Optional[int] = 1,
eta: float = 0.0,
generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
latents: Optional[torch.FloatTensor] = None,
prompt_embeds: Optional[torch.FloatTensor] = None,
negative_prompt_embeds: Optional[torch.FloatTensor] = None,
output_type: Optional[str] = "pil",
return_dict: bool = True,
callback: Optional[Callable[[int, int, torch.FloatTensor], None]] = None,
callback_steps: int = 1,
cross_attention_kwargs: Optional[Dict[str, Any]] = None,
guidance_rescale: float = 0.0,
):
# 0. Default height and width to unet
height = height or self.unet.config.sample_size * self.vae_scale_factor
width = width or self.unet.config.sample_size * self.vae_scale_factor
# 1. Check inputs. Raise error if not correct
self.check_inputs(
prompt, height, width, callback_steps, negative_prompt, prompt_embeds, negative_prompt_embeds
)
# 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 = self._execution_device
# here `guidance_scale` is defined analog to the guidance weight `w` of equation (2)
# of the Imagen paper: https://arxiv.org/pdf/2205.11487.pdf . `guidance_scale = 1`
# corresponds to doing no classifier free guidance.
do_classifier_free_guidance = guidance_scale > 1.0
# 3. Encode input prompt
text_encoder_lora_scale = (
cross_attention_kwargs.get("scale", None) if cross_attention_kwargs is not None else None
)
prompt_embeds = self._encode_prompt(
prompt,
device,
num_images_per_prompt,
do_classifier_free_guidance,
negative_prompt,
prompt_embeds=prompt_embeds,
negative_prompt_embeds=negative_prompt_embeds,
lora_scale=text_encoder_lora_scale,
)
# 4. Prepare timesteps
self.scheduler.set_timesteps(num_inference_steps, device=device)
timesteps = self.scheduler.timesteps
# 5. Prepare latent variables
num_channels_latents = self.unet.config.in_channels
latents = self.prepare_latents(
batch_size * num_images_per_prompt,
num_channels_latents,
height,
width,
prompt_embeds.dtype,
device,
generator,
latents,
)
# 6. Prepare extra step kwargs. TODO: Logic should ideally just be moved out of the pipeline
extra_step_kwargs = self.prepare_extra_step_kwargs(generator, eta)
# 7. Denoising loop
num_warmup_steps = len(timesteps) - num_inference_steps * self.scheduler.order
with self.progress_bar(total=num_inference_steps) as progress_bar:
for i, t in enumerate(timesteps):
# expand the latents if we are doing classifier free guidance
latent_model_input = torch.cat([latents] * 2) if do_classifier_free_guidance else latents
latent_model_input = self.scheduler.scale_model_input(latent_model_input, t)
# predict the noise residual
noise_pred = self.unet(
latent_model_input,
t,
encoder_hidden_states=prompt_embeds,
cross_attention_kwargs=cross_attention_kwargs,
return_dict=False,
)[0]
# perform guidance
if do_classifier_free_guidance:
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
if do_classifier_free_guidance and guidance_rescale > 0.0:
# Based on 3.4. in https://arxiv.org/pdf/2305.08891.pdf
noise_pred = rescale_noise_cfg(noise_pred, noise_pred_text, guidance_rescale=guidance_rescale)
# compute the previous noisy sample x_t -> x_t-1
latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs, return_dict=False)[0]
# call the callback, if provided
if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0):
progress_bar.update()
if callback is not None and i % callback_steps == 0:
callback(i, t, latents)
if not output_type == "latent":
image = self.vae.decode(latents / self.vae.config.scaling_factor, return_dict=False)[0]
image, has_nsfw_concept = self.run_safety_checker(image, device, prompt_embeds.dtype)
else:
image = latents
has_nsfw_concept = None
if has_nsfw_concept is None:
do_denormalize = [True] * image.shape[0]
else:
do_denormalize = [not has_nsfw for has_nsfw in has_nsfw_concept]
image = self.image_processor.postprocess(image, output_type=output_type, do_denormalize=do_denormalize)
# Offload last model to CPU
if hasattr(self, "final_offload_hook") and self.final_offload_hook is not None:
self.final_offload_hook.offload()
if not return_dict:
return (image, has_nsfw_concept)
return StableDiffusionPipelineOutput(images=image, nsfw_content_detected=has_nsfw_concept)