update diffusers

Signed-off-by: Vladimir Mandic <mandic00@live.com>
This commit is contained in:
Vladimir Mandic
2025-04-14 09:10:01 -04:00
parent 76b5709f51
commit cf1606ea11
2 changed files with 161 additions and 158 deletions
+1 -1
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@@ -538,7 +538,7 @@ def check_diffusers():
t_start = time.time()
if args.skip_all or args.skip_git or args.experimental:
return
sha = '0ef29355c9d65b78eabb6a4ac5bee73aa685e9a6' # diffusers commit hash
sha = 'a8f5134c113da402a93580ef7a021557e816c98d' # diffusers commit hash
pkg = pkg_resources.working_set.by_key.get('diffusers', None)
minor = int(pkg.version.split('.')[1] if pkg is not None else 0)
cur = opts.get('diffusers_version', '') if minor > 0 else ''
+160 -157
View File
@@ -1,47 +1,26 @@
import inspect
from typing import Any, Callable, Dict, List, Optional, Union
import math
import einops
from typing import Any, Callable, Dict, List, Optional, Union
import torch
from transformers import (
CLIPTextModelWithProjection,
CLIPTokenizer,
LlamaForCausalLM,
PreTrainedTokenizerFast,
T5EncoderModel,
T5Tokenizer,
LlamaForCausalLM,
PreTrainedTokenizerFast
)
from diffusers.image_processor import VaeImageProcessor
from diffusers.loaders import FromSingleFileMixin
from diffusers.models.autoencoders import AutoencoderKL
from diffusers.schedulers import FlowMatchEulerDiscreteScheduler
from diffusers.utils import (
USE_PEFT_BACKEND,
is_torch_xla_available,
logging,
)
from diffusers.models import AutoencoderKL, HiDreamImageTransformer2DModel
from diffusers.schedulers import FlowMatchEulerDiscreteScheduler, UniPCMultistepScheduler
from diffusers.utils import is_torch_xla_available, logging
from diffusers.utils.torch_utils import randn_tensor
from diffusers.pipelines.pipeline_utils import DiffusionPipeline
from diffusers.pipelines.hidream_image.pipeline_output import HiDreamImagePipelineOutput
from diffusers.models.transformers.transformer_hidream_image import HiDreamImageTransformer2DModel
from modules.schedulers.scheduler_unipc_flowmatch import FlowUniPCMultistepScheduler
@torch.cuda.amp.autocast(dtype=torch.float32)
def optimized_scale(positive_flat, negative_flat):
# Calculate dot production
dot_product = torch.sum(positive_flat * negative_flat, dim=1, keepdim=True)
# Squared norm of uncondition
squared_norm = torch.sum(negative_flat ** 2, dim=1, keepdim=True) + 1e-8
# st_star = v_cond^T * v_uncond / ||v_uncond||^2
st_star = dot_product / squared_norm
return st_star
if is_torch_xla_available():
import torch_xla.core.xla_model as xm
@@ -49,8 +28,69 @@ if is_torch_xla_available():
else:
XLA_AVAILABLE = False
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
EXAMPLE_DOC_STRING = """
Examples:
```py
>>> import torch
>>> from transformers import PreTrainedTokenizerFast, LlamaForCausalLM
>>> from diffusers import UniPCMultistepScheduler, HiDreamImagePipeline, HiDreamImageTransformer2DModel
>>> scheduler = UniPCMultistepScheduler(
... flow_shift=3.0, prediction_type="flow_prediction", use_flow_sigmas=True
... )
>>> tokenizer_4 = PreTrainedTokenizerFast.from_pretrained("meta-llama/Meta-Llama-3.1-8B-Instruct")
>>> text_encoder_4 = LlamaForCausalLM.from_pretrained(
... "meta-llama/Meta-Llama-3.1-8B-Instruct",
... output_hidden_states=True,
... output_attentions=True,
... torch_dtype=torch.bfloat16,
... )
>>> transformer = HiDreamImageTransformer2DModel.from_pretrained(
... "HiDream-ai/HiDream-I1-Full", subfolder="transformer", torch_dtype=torch.bfloat16
... )
>>> pipe = HiDreamImagePipeline.from_pretrained(
... "HiDream-ai/HiDream-I1-Full",
... scheduler=scheduler,
... tokenizer_4=tokenizer_4,
... text_encoder_4=text_encoder_4,
... transformer=transformer,
... torch_dtype=torch.bfloat16,
... )
>>> pipe.enable_model_cpu_offload()
>>> image = pipe(
... 'A cat holding a sign that says "Hi-Dreams.ai".',
... height=1024,
... width=1024,
... guidance_scale=5.0,
... num_inference_steps=50,
... generator=torch.Generator("cuda").manual_seed(0),
... ).images[0]
>>> image.save("output.png")
```
"""
@torch.cuda.amp.autocast(dtype=torch.float32)
def optimized_scale(positive_flat, negative_flat):
# Calculate dot production
dot_product = torch.sum(positive_flat * negative_flat, dim=1, keepdim=True)
# Squared norm of uncondition
squared_norm = torch.sum(negative_flat ** 2, dim=1, keepdim=True) + 1e-8
# st_star = v_cond^T * v_uncond / ||v_uncond||^2
st_star = dot_product / squared_norm
return st_star
# Copied from diffusers.pipelines.flux.pipeline_flux.calculate_shift
def calculate_shift(
image_seq_len,
@@ -64,6 +104,7 @@ def calculate_shift(
mu = image_seq_len * m + b
return mu
# Copied from diffusers.pipelines.stable_diffusion.pipeline_stable_diffusion.retrieve_timesteps
def retrieve_timesteps(
scheduler,
@@ -123,9 +164,9 @@ def retrieve_timesteps(
timesteps = scheduler.timesteps
return timesteps, num_inference_steps
class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
model_cpu_offload_seq = "text_encoder->text_encoder_2->text_encoder_3->text_encoder_4->image_encoder->transformer->vae"
_optional_components = ["image_encoder", "feature_extractor"]
class HiDreamImageCFGZeroPipeline(DiffusionPipeline):
model_cpu_offload_seq = "text_encoder->text_encoder_2->text_encoder_3->text_encoder_4->transformer->vae"
_callback_tensor_inputs = ["latents", "prompt_embeds"]
def __init__(
@@ -140,6 +181,7 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
tokenizer_3: T5Tokenizer,
text_encoder_4: LlamaForCausalLM,
tokenizer_4: PreTrainedTokenizerFast,
transformer: HiDreamImageTransformer2DModel,
):
super().__init__()
@@ -154,6 +196,7 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
tokenizer_3=tokenizer_3,
tokenizer_4=tokenizer_4,
scheduler=scheduler,
transformer=transformer,
)
self.vae_scale_factor = (
2 ** (len(self.vae.config.block_out_channels) - 1) if hasattr(self, "vae") and self.vae is not None else 8
@@ -162,12 +205,12 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
# by the patch size. So the vae scale factor is multiplied by the patch size to account for this
self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor * 2)
self.default_sample_size = 128
self.tokenizer_4.pad_token = self.tokenizer_4.eos_token
if getattr(self, "tokenizer_4", None) is not None:
self.tokenizer_4.pad_token = self.tokenizer_4.eos_token
def _get_t5_prompt_embeds(
self,
prompt: Union[str, List[str]] = None,
num_images_per_prompt: int = 1,
max_sequence_length: int = 128,
device: Optional[torch.device] = None,
dtype: Optional[torch.dtype] = None,
@@ -176,7 +219,6 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
dtype = dtype or self.text_encoder_3.dtype
prompt = [prompt] if isinstance(prompt, str) else prompt
batch_size = len(prompt)
text_inputs = self.tokenizer_3(
prompt,
@@ -191,7 +233,9 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
untruncated_ids = self.tokenizer_3(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_3.batch_decode(untruncated_ids[:, min(max_sequence_length, self.tokenizer_3.model_max_length) - 1 : -1])
removed_text = self.tokenizer_3.batch_decode(
untruncated_ids[:, min(max_sequence_length, self.tokenizer_3.model_max_length) - 1 : -1]
)
logger.warning(
"The following part of your input was truncated because `max_sequence_length` is set to "
f" {min(max_sequence_length, self.tokenizer_3.model_max_length)} tokens: {removed_text}"
@@ -199,19 +243,13 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
prompt_embeds = self.text_encoder_3(text_input_ids.to(device), attention_mask=attention_mask.to(device))[0]
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
def _get_clip_prompt_embeds(
self,
tokenizer,
text_encoder,
prompt: Union[str, List[str]],
num_images_per_prompt: int = 1,
max_sequence_length: int = 128,
device: Optional[torch.device] = None,
dtype: Optional[torch.dtype] = None,
@@ -220,7 +258,6 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
dtype = dtype or text_encoder.dtype
prompt = [prompt] if isinstance(prompt, str) else prompt
batch_size = len(prompt)
text_inputs = tokenizer(
prompt,
@@ -243,17 +280,11 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
# Use pooled output of CLIPTextModel
prompt_embeds = prompt_embeds[0]
prompt_embeds = prompt_embeds.to(dtype=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)
prompt_embeds = prompt_embeds.view(batch_size * num_images_per_prompt, -1)
return prompt_embeds
def _get_llama3_prompt_embeds(
self,
prompt: Union[str, List[str]] = None,
num_images_per_prompt: int = 1,
max_sequence_length: int = 128,
device: Optional[torch.device] = None,
dtype: Optional[torch.dtype] = None,
@@ -262,7 +293,6 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
dtype = dtype or self.text_encoder_4.dtype
prompt = [prompt] if isinstance(prompt, str) else prompt
batch_size = len(prompt)
text_inputs = self.tokenizer_4(
prompt,
@@ -277,28 +307,25 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
untruncated_ids = self.tokenizer_4(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_4.batch_decode(untruncated_ids[:, min(max_sequence_length, self.tokenizer_4.model_max_length) - 1 : -1])
removed_text = self.tokenizer_4.batch_decode(
untruncated_ids[:, min(max_sequence_length, self.tokenizer_4.model_max_length) - 1 : -1]
)
logger.warning(
"The following part of your input was truncated because `max_sequence_length` is set to "
f" {min(max_sequence_length, self.tokenizer_4.model_max_length)} tokens: {removed_text}"
)
outputs = self.text_encoder_4(
text_input_ids.to(device),
attention_mask=attention_mask.to(device),
text_input_ids.to(device),
attention_mask=attention_mask.to(device),
output_hidden_states=True,
output_attentions=True
output_attentions=True,
)
prompt_embeds = outputs.hidden_states[1:]
prompt_embeds = torch.stack(prompt_embeds, dim=0)
_, _, seq_len, dim = prompt_embeds.shape
# duplicate text embeddings and attention mask for each generation per prompt, using mps friendly method
prompt_embeds = prompt_embeds.repeat(1, 1, num_images_per_prompt, 1)
prompt_embeds = prompt_embeds.view(-1, batch_size * num_images_per_prompt, seq_len, dim)
return prompt_embeds
def encode_prompt(
self,
prompt: Union[str, List[str]],
@@ -324,19 +351,19 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
if prompt is not None:
batch_size = len(prompt)
else:
batch_size = prompt_embeds.shape[0]
batch_size = prompt_embeds[0].shape[0] if isinstance(prompt_embeds, list) else prompt_embeds.shape[0]
prompt_embeds, pooled_prompt_embeds = self._encode_prompt(
prompt = prompt,
prompt_2 = prompt_2,
prompt_3 = prompt_3,
prompt_4 = prompt_4,
device = device,
dtype = dtype,
num_images_per_prompt = num_images_per_prompt,
prompt_embeds = prompt_embeds,
pooled_prompt_embeds = pooled_prompt_embeds,
max_sequence_length = max_sequence_length,
prompt=prompt,
prompt_2=prompt_2,
prompt_3=prompt_3,
prompt_4=prompt_4,
device=device,
dtype=dtype,
num_images_per_prompt=num_images_per_prompt,
prompt_embeds=prompt_embeds,
pooled_prompt_embeds=pooled_prompt_embeds,
max_sequence_length=max_sequence_length,
)
if do_classifier_free_guidance and negative_prompt_embeds is None:
@@ -368,18 +395,18 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
f" {prompt} has batch size {batch_size}. Please make sure that passed `negative_prompt` matches"
" the batch size of `prompt`."
)
negative_prompt_embeds, negative_pooled_prompt_embeds = self._encode_prompt(
prompt = negative_prompt,
prompt_2 = negative_prompt_2,
prompt_3 = negative_prompt_3,
prompt_4 = negative_prompt_4,
device = device,
dtype = dtype,
num_images_per_prompt = num_images_per_prompt,
prompt_embeds = negative_prompt_embeds,
pooled_prompt_embeds = negative_pooled_prompt_embeds,
max_sequence_length = max_sequence_length,
prompt=negative_prompt,
prompt_2=negative_prompt_2,
prompt_3=negative_prompt_3,
prompt_4=negative_prompt_4,
device=device,
dtype=dtype,
num_images_per_prompt=num_images_per_prompt,
prompt_embeds=negative_prompt_embeds,
pooled_prompt_embeds=negative_pooled_prompt_embeds,
max_sequence_length=max_sequence_length,
)
return prompt_embeds, negative_prompt_embeds, pooled_prompt_embeds, negative_pooled_prompt_embeds
@@ -397,53 +424,44 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
max_sequence_length: int = 128,
):
device = device or self._execution_device
if prompt_embeds is None:
if prompt is not None:
batch_size = len(prompt)
else:
batch_size = prompt_embeds[0].shape[0] if isinstance(prompt_embeds, list) else prompt_embeds.shape[0]
if pooled_prompt_embeds is None:
prompt_2 = prompt_2 or prompt
prompt_2 = [prompt_2] if isinstance(prompt_2, str) else prompt_2
pooled_prompt_embeds_1 = self._get_clip_prompt_embeds(
self.tokenizer, self.text_encoder, prompt, max_sequence_length, device, dtype
)
pooled_prompt_embeds_2 = self._get_clip_prompt_embeds(
self.tokenizer_2, self.text_encoder_2, prompt_2, max_sequence_length, device, dtype
)
pooled_prompt_embeds = torch.cat([pooled_prompt_embeds_1, pooled_prompt_embeds_2], dim=-1)
pooled_prompt_embeds = pooled_prompt_embeds.repeat(1, num_images_per_prompt)
pooled_prompt_embeds = pooled_prompt_embeds.view(batch_size * num_images_per_prompt, -1)
if prompt_embeds is None:
prompt_3 = prompt_3 or prompt
prompt_3 = [prompt_3] if isinstance(prompt_3, str) else prompt_3
prompt_4 = prompt_4 or prompt
prompt_4 = [prompt_4] if isinstance(prompt_4, str) else prompt_4
pooled_prompt_embeds_1 = self._get_clip_prompt_embeds(
self.tokenizer,
self.text_encoder,
prompt = prompt,
num_images_per_prompt = num_images_per_prompt,
max_sequence_length = max_sequence_length,
device = device,
dtype = dtype,
)
t5_prompt_embeds = self._get_t5_prompt_embeds(prompt_3, max_sequence_length, device, dtype)
llama3_prompt_embeds = self._get_llama3_prompt_embeds(prompt_4, max_sequence_length, device, dtype)
pooled_prompt_embeds_2 = self._get_clip_prompt_embeds(
self.tokenizer_2,
self.text_encoder_2,
prompt = prompt_2,
num_images_per_prompt = num_images_per_prompt,
max_sequence_length = max_sequence_length,
device = device,
dtype = dtype,
)
_, seq_len, _ = t5_prompt_embeds.shape
t5_prompt_embeds = t5_prompt_embeds.repeat(1, num_images_per_prompt, 1)
t5_prompt_embeds = t5_prompt_embeds.view(batch_size * num_images_per_prompt, seq_len, -1)
pooled_prompt_embeds = torch.cat([pooled_prompt_embeds_1, pooled_prompt_embeds_2], dim=-1)
_, _, seq_len, dim = llama3_prompt_embeds.shape
llama3_prompt_embeds = llama3_prompt_embeds.repeat(1, 1, num_images_per_prompt, 1)
llama3_prompt_embeds = llama3_prompt_embeds.view(-1, batch_size * num_images_per_prompt, seq_len, dim)
t5_prompt_embeds = self._get_t5_prompt_embeds(
prompt = prompt_3,
num_images_per_prompt = num_images_per_prompt,
max_sequence_length = max_sequence_length,
device = device,
dtype = dtype
)
llama3_prompt_embeds = self._get_llama3_prompt_embeds(
prompt = prompt_4,
num_images_per_prompt = num_images_per_prompt,
max_sequence_length = max_sequence_length,
device = device,
dtype = dtype
)
prompt_embeds = [t5_prompt_embeds, llama3_prompt_embeds]
return prompt_embeds, pooled_prompt_embeds
@@ -502,19 +520,19 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
raise ValueError(f"Unexpected latents shape, got {latents.shape}, expected {shape}")
latents = latents.to(device)
return latents
@property
def guidance_scale(self):
return self._guidance_scale
@property
def do_classifier_free_guidance(self):
return self._guidance_scale > 1
@property
def joint_attention_kwargs(self):
return self._joint_attention_kwargs
def attention_kwargs(self):
return self._attention_kwargs
@property
def num_timesteps(self):
return self._num_timesteps
@@ -522,7 +540,7 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
@property
def interrupt(self):
return self._interrupt
@torch.no_grad()
def __call__(
self,
@@ -548,13 +566,13 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
negative_pooled_prompt_embeds: Optional[torch.FloatTensor] = None,
output_type: Optional[str] = "pil",
return_dict: bool = True,
joint_attention_kwargs: Optional[Dict[str, Any]] = None,
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 = 128,
use_cfg_zero_star: Optional[bool] = True,
use_zero_init: Optional[bool] = True,
zero_steps: Optional[int] = 1,
zero_steps: Optional[int] = 0,
):
height = height or self.default_sample_size * self.vae_scale_factor
width = width or self.default_sample_size * self.vae_scale_factor
@@ -566,7 +584,7 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
width, height = int(width * scale // division * division), int(height * scale // division * division)
self._guidance_scale = guidance_scale
self._joint_attention_kwargs = joint_attention_kwargs
self._attention_kwargs = attention_kwargs
self._interrupt = False
# 2. Define call parameters
@@ -574,14 +592,14 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
batch_size = 1
elif prompt is not None and isinstance(prompt, list):
batch_size = len(prompt)
elif prompt_embeds is not None:
batch_size = prompt_embeds[0].shape[0] if isinstance(prompt_embeds, list) else prompt_embeds.shape[0]
else:
batch_size = prompt_embeds.shape[0]
batch_size = 1
device = self._execution_device
lora_scale = (
self.joint_attention_kwargs.get("scale", None) if self.joint_attention_kwargs is not None else None
)
lora_scale = self.attention_kwargs.get("scale", None) if self.attention_kwargs is not None else None
(
prompt_embeds,
negative_prompt_embeds,
@@ -640,7 +658,7 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
img_ids[..., 2] = img_ids[..., 2] + torch.arange(pW)[None, :]
img_ids = img_ids.reshape(pH * pW, -1)
img_ids_pad = torch.zeros(self.transformer.max_seq, 3)
img_ids_pad[:pH*pW, :] = img_ids
img_ids_pad[: pH * pW, :] = img_ids
img_sizes = img_sizes.unsqueeze(0).to(latents.device)
img_ids = img_ids_pad.unsqueeze(0).to(latents.device)
@@ -653,8 +671,8 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
# 5. Prepare timesteps
mu = calculate_shift(self.transformer.max_seq)
scheduler_kwargs = {"mu": mu}
if isinstance(self.scheduler, FlowUniPCMultistepScheduler):
self.scheduler.set_timesteps(num_inference_steps, device=device, shift=math.exp(mu))
if isinstance(self.scheduler, UniPCMultistepScheduler):
self.scheduler.set_timesteps(num_inference_steps, device=device) # , shift=math.exp(mu))
timesteps = self.scheduler.timesteps
else:
timesteps, num_inference_steps = retrieve_timesteps(
@@ -678,35 +696,20 @@ class HiDreamImageCFGZeroPipeline(DiffusionPipeline, FromSingleFileMixin):
# broadcast to batch dimension in a way that's compatible with ONNX/Core ML
timestep = t.expand(latent_model_input.shape[0])
if latent_model_input.shape[-2] != latent_model_input.shape[-1]:
B, C, H, W = latent_model_input.shape
patch_size = self.transformer.config.patch_size
pH, pW = H // patch_size, W // patch_size
out = torch.zeros(
(B, C, self.transformer.max_seq, patch_size * patch_size),
dtype=latent_model_input.dtype,
device=latent_model_input.device
)
latent_model_input = einops.rearrange(latent_model_input, 'B C (H p1) (W p2) -> B C (H W) (p1 p2)', p1=patch_size, p2=patch_size)
out[:, :, 0:pH*pW] = latent_model_input
latent_model_input = out
noise_pred = self.transformer(
hidden_states = latent_model_input,
timesteps = timestep,
encoder_hidden_states = prompt_embeds,
pooled_embeds = pooled_prompt_embeds,
img_sizes = img_sizes,
img_ids = img_ids,
return_dict = False,
hidden_states=latent_model_input,
timesteps=timestep,
encoder_hidden_states=prompt_embeds,
pooled_embeds=pooled_prompt_embeds,
img_sizes=img_sizes,
img_ids=img_ids,
return_dict=False,
)[0]
noise_pred = -noise_pred
# perform guidance
if self.do_classifier_free_guidance:
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
if use_cfg_zero_star:
positive_flat = noise_pred_text.view(batch_size, -1)
negative_flat = noise_pred_uncond.view(batch_size, -1)