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import types
from typing import List, Optional, Tuple, Union
import torch
from transformers import CLIPTextModelWithProjection, CLIPTokenizer
from transformers.models.clip.modeling_clip import CLIPTextModelOutput
from diffusers.models import PriorTransformer
from diffusers.pipelines import DiffusionPipeline, StableDiffusionImageVariationPipeline
from diffusers.schedulers import UnCLIPScheduler
from diffusers.utils import logging, randn_tensor
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
def _encode_image(self, image, device, num_images_per_prompt, do_classifier_free_guidance):
image = image.to(device=device)
image_embeddings = image # take image as image_embeddings
image_embeddings = image_embeddings.unsqueeze(1)
# duplicate image embeddings for each generation per prompt, using mps friendly method
bs_embed, seq_len, _ = image_embeddings.shape
image_embeddings = image_embeddings.repeat(1, num_images_per_prompt, 1)
image_embeddings = image_embeddings.view(bs_embed * num_images_per_prompt, seq_len, -1)
if do_classifier_free_guidance:
uncond_embeddings = torch.zeros_like(image_embeddings)
# 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
image_embeddings = torch.cat([uncond_embeddings, image_embeddings])
return image_embeddings
class StableUnCLIPPipeline(DiffusionPipeline):
def __init__(
self,
prior: PriorTransformer,
tokenizer: CLIPTokenizer,
text_encoder: CLIPTextModelWithProjection,
prior_scheduler: UnCLIPScheduler,
decoder_pipe_kwargs: Optional[dict] = None,
):
super().__init__()
decoder_pipe_kwargs = {"image_encoder": None} if decoder_pipe_kwargs is None else decoder_pipe_kwargs
decoder_pipe_kwargs["torch_dtype"] = decoder_pipe_kwargs.get("torch_dtype", None) or prior.dtype
self.decoder_pipe = StableDiffusionImageVariationPipeline.from_pretrained(
"lambdalabs/sd-image-variations-diffusers", **decoder_pipe_kwargs
)
# replace `_encode_image` method
self.decoder_pipe._encode_image = types.MethodType(_encode_image, self.decoder_pipe)
self.register_modules(
prior=prior,
tokenizer=tokenizer,
text_encoder=text_encoder,
prior_scheduler=prior_scheduler,
)
def _encode_prompt(
self,
prompt,
device,
num_images_per_prompt,
do_classifier_free_guidance,
text_model_output: Optional[Union[CLIPTextModelOutput, Tuple]] = None,
text_attention_mask: Optional[torch.Tensor] = None,
):
if text_model_output is None:
batch_size = len(prompt) if isinstance(prompt, list) else 1
# get prompt text embeddings
text_inputs = self.tokenizer(
prompt,
padding="max_length",
max_length=self.tokenizer.model_max_length,
return_tensors="pt",
)
text_input_ids = text_inputs.input_ids
text_mask = text_inputs.attention_mask.bool().to(device)
if text_input_ids.shape[-1] > self.tokenizer.model_max_length:
removed_text = self.tokenizer.batch_decode(text_input_ids[:, self.tokenizer.model_max_length :])
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}"
)
text_input_ids = text_input_ids[:, : self.tokenizer.model_max_length]
text_encoder_output = self.text_encoder(text_input_ids.to(device))
text_embeddings = text_encoder_output.text_embeds
text_encoder_hidden_states = text_encoder_output.last_hidden_state
else:
batch_size = text_model_output[0].shape[0]
text_embeddings, text_encoder_hidden_states = text_model_output[0], text_model_output[1]
text_mask = text_attention_mask
text_embeddings = text_embeddings.repeat_interleave(num_images_per_prompt, dim=0)
text_encoder_hidden_states = text_encoder_hidden_states.repeat_interleave(num_images_per_prompt, dim=0)
text_mask = text_mask.repeat_interleave(num_images_per_prompt, dim=0)
if do_classifier_free_guidance:
uncond_tokens = [""] * batch_size
uncond_input = self.tokenizer(
uncond_tokens,
padding="max_length",
max_length=self.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
uncond_text_mask = uncond_input.attention_mask.bool().to(device)
uncond_embeddings_text_encoder_output = self.text_encoder(uncond_input.input_ids.to(device))
uncond_embeddings = uncond_embeddings_text_encoder_output.text_embeds
uncond_text_encoder_hidden_states = uncond_embeddings_text_encoder_output.last_hidden_state
# duplicate unconditional embeddings for each generation per prompt, using mps friendly method
seq_len = uncond_embeddings.shape[1]
uncond_embeddings = uncond_embeddings.repeat(1, num_images_per_prompt)
uncond_embeddings = uncond_embeddings.view(batch_size * num_images_per_prompt, seq_len)
seq_len = uncond_text_encoder_hidden_states.shape[1]
uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.repeat(1, num_images_per_prompt, 1)
uncond_text_encoder_hidden_states = uncond_text_encoder_hidden_states.view(
batch_size * num_images_per_prompt, seq_len, -1
)
uncond_text_mask = uncond_text_mask.repeat_interleave(num_images_per_prompt, dim=0)
# done duplicates
# 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
text_embeddings = torch.cat([uncond_embeddings, text_embeddings])
text_encoder_hidden_states = torch.cat([uncond_text_encoder_hidden_states, text_encoder_hidden_states])
text_mask = torch.cat([uncond_text_mask, text_mask])
return text_embeddings, text_encoder_hidden_states, text_mask
@property
def _execution_device(self):
r"""
Returns the device on which the pipeline's models will be executed. After calling
`pipeline.enable_sequential_cpu_offload()` the execution device can only be inferred from Accelerate's module
hooks.
"""
if self.device != torch.device("meta") or not hasattr(self.prior, "_hf_hook"):
return self.device
for module in self.prior.modules():
if (
hasattr(module, "_hf_hook")
and hasattr(module._hf_hook, "execution_device")
and module._hf_hook.execution_device is not None
):
return torch.device(module._hf_hook.execution_device)
return self.device
def prepare_latents(self, shape, dtype, device, generator, latents, scheduler):
if latents is None:
latents = randn_tensor(shape, generator=generator, device=device, dtype=dtype)
else:
if latents.shape != shape:
raise ValueError(f"Unexpected latents shape, got {latents.shape}, expected {shape}")
latents = latents.to(device)
latents = latents * scheduler.init_noise_sigma
return latents
def to(self, torch_device: Optional[Union[str, torch.device]] = None):
self.decoder_pipe.to(torch_device)
super().to(torch_device)
@torch.no_grad()
def __call__(
self,
prompt: Optional[Union[str, List[str]]] = None,
height: Optional[int] = None,
width: Optional[int] = None,
num_images_per_prompt: int = 1,
prior_num_inference_steps: int = 25,
generator: Optional[torch.Generator] = None,
prior_latents: Optional[torch.FloatTensor] = None,
text_model_output: Optional[Union[CLIPTextModelOutput, Tuple]] = None,
text_attention_mask: Optional[torch.Tensor] = None,
prior_guidance_scale: float = 4.0,
decoder_guidance_scale: float = 8.0,
decoder_num_inference_steps: int = 50,
decoder_num_images_per_prompt: Optional[int] = 1,
decoder_eta: float = 0.0,
output_type: Optional[str] = "pil",
return_dict: bool = True,
):
if prompt is not None:
if isinstance(prompt, str):
batch_size = 1
elif isinstance(prompt, list):
batch_size = len(prompt)
else:
raise ValueError(f"`prompt` has to be of type `str` or `list` but is {type(prompt)}")
else:
batch_size = text_model_output[0].shape[0]
device = self._execution_device
batch_size = batch_size * num_images_per_prompt
do_classifier_free_guidance = prior_guidance_scale > 1.0 or decoder_guidance_scale > 1.0
text_embeddings, text_encoder_hidden_states, text_mask = self._encode_prompt(
prompt, device, num_images_per_prompt, do_classifier_free_guidance, text_model_output, text_attention_mask
)
# prior
self.prior_scheduler.set_timesteps(prior_num_inference_steps, device=device)
prior_timesteps_tensor = self.prior_scheduler.timesteps
embedding_dim = self.prior.config.embedding_dim
prior_latents = self.prepare_latents(
(batch_size, embedding_dim),
text_embeddings.dtype,
device,
generator,
prior_latents,
self.prior_scheduler,
)
for i, t in enumerate(self.progress_bar(prior_timesteps_tensor)):
# expand the latents if we are doing classifier free guidance
latent_model_input = torch.cat([prior_latents] * 2) if do_classifier_free_guidance else prior_latents
predicted_image_embedding = self.prior(
latent_model_input,
timestep=t,
proj_embedding=text_embeddings,
encoder_hidden_states=text_encoder_hidden_states,
attention_mask=text_mask,
).predicted_image_embedding
if do_classifier_free_guidance:
predicted_image_embedding_uncond, predicted_image_embedding_text = predicted_image_embedding.chunk(2)
predicted_image_embedding = predicted_image_embedding_uncond + prior_guidance_scale * (
predicted_image_embedding_text - predicted_image_embedding_uncond
)
if i + 1 == prior_timesteps_tensor.shape[0]:
prev_timestep = None
else:
prev_timestep = prior_timesteps_tensor[i + 1]
prior_latents = self.prior_scheduler.step(
predicted_image_embedding,
timestep=t,
sample=prior_latents,
generator=generator,
prev_timestep=prev_timestep,
).prev_sample
prior_latents = self.prior.post_process_latents(prior_latents)
image_embeddings = prior_latents
output = self.decoder_pipe(
image=image_embeddings,
height=height,
width=width,
num_inference_steps=decoder_num_inference_steps,
guidance_scale=decoder_guidance_scale,
generator=generator,
output_type=output_type,
return_dict=return_dict,
num_images_per_prompt=decoder_num_images_per_prompt,
eta=decoder_eta,
)
return output
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