# Copyright 2022 Kakao Brain 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.
import inspect
from typing import List, Optional, Tuple, Union
import torch
from torch.nn import functional as F
from transformers import CLIPTextModelWithProjection, CLIPTokenizer
from transformers.models.clip.modeling_clip import CLIPTextModelOutput
from ...models import PriorTransformer, UNet2DConditionModel, UNet2DModel
from ...pipelines import DiffusionPipeline, ImagePipelineOutput
from ...schedulers import UnCLIPScheduler
from ...utils import is_accelerate_available, logging, randn_tensor
from .text_proj import UnCLIPTextProjModel
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
class UnCLIPPipeline(DiffusionPipeline):
"""
Pipeline for text-to-image generation using unCLIP
This model inherits from [`DiffusionPipeline`]. Check the superclass documentation for the generic methods the
library implements for all the pipelines (such as downloading or saving, running on a particular device, etc.)
Args:
text_encoder ([`CLIPTextModelWithProjection`]):
Frozen text-encoder.
tokenizer (`CLIPTokenizer`):
Tokenizer of class
[CLIPTokenizer](https://huggingface.co/docs/transformers/v4.21.0/en/model_doc/clip#transformers.CLIPTokenizer).
prior ([`PriorTransformer`]):
The canonincal unCLIP prior to approximate the image embedding from the text embedding.
text_proj ([`UnCLIPTextProjModel`]):
Utility class to prepare and combine the embeddings before they are passed to the decoder.
decoder ([`UNet2DConditionModel`]):
The decoder to invert the image embedding into an image.
super_res_first ([`UNet2DModel`]):
Super resolution unet. Used in all but the last step of the super resolution diffusion process.
super_res_last ([`UNet2DModel`]):
Super resolution unet. Used in the last step of the super resolution diffusion process.
prior_scheduler ([`UnCLIPScheduler`]):
Scheduler used in the prior denoising process. Just a modified DDPMScheduler.
decoder_scheduler ([`UnCLIPScheduler`]):
Scheduler used in the decoder denoising process. Just a modified DDPMScheduler.
super_res_scheduler ([`UnCLIPScheduler`]):
Scheduler used in the super resolution denoising process. Just a modified DDPMScheduler.
"""
prior: PriorTransformer
decoder: UNet2DConditionModel
text_proj: UnCLIPTextProjModel
text_encoder: CLIPTextModelWithProjection
tokenizer: CLIPTokenizer
super_res_first: UNet2DModel
super_res_last: UNet2DModel
prior_scheduler: UnCLIPScheduler
decoder_scheduler: UnCLIPScheduler
super_res_scheduler: UnCLIPScheduler
def __init__(
self,
prior: PriorTransformer,
decoder: UNet2DConditionModel,
text_encoder: CLIPTextModelWithProjection,
tokenizer: CLIPTokenizer,
text_proj: UnCLIPTextProjModel,
super_res_first: UNet2DModel,
super_res_last: UNet2DModel,
prior_scheduler: UnCLIPScheduler,
decoder_scheduler: UnCLIPScheduler,
super_res_scheduler: UnCLIPScheduler,
):
super().__init__()
self.register_modules(
prior=prior,
decoder=decoder,
text_encoder=text_encoder,
tokenizer=tokenizer,
text_proj=text_proj,
super_res_first=super_res_first,
super_res_last=super_res_last,
prior_scheduler=prior_scheduler,
decoder_scheduler=decoder_scheduler,
super_res_scheduler=super_res_scheduler,
)
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 _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
def enable_sequential_cpu_offload(self, gpu_id=0):
r"""
Offloads all models to CPU using accelerate, significantly reducing memory usage. When called, the pipeline's
models have their state dicts saved to CPU and then are moved to a `torch.device('meta') and loaded to GPU only
when their specific submodule has its `forward` method called.
"""
if is_accelerate_available():
from accelerate import cpu_offload
else:
raise ImportError("Please install accelerate via `pip install accelerate`")
device = torch.device(f"cuda:{gpu_id}")
# TODO: self.prior.post_process_latents is not covered by the offload hooks, so it fails if added to the list
models = [
self.decoder,
self.text_proj,
self.text_encoder,
self.super_res_first,
self.super_res_last,
]
for cpu_offloaded_model in models:
if cpu_offloaded_model is not None:
cpu_offload(cpu_offloaded_model, device)
@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.decoder, "_hf_hook"):
return self.device
for module in self.decoder.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
@torch.no_grad()
def __call__(
self,
prompt: Optional[Union[str, List[str]]] = None,
num_images_per_prompt: int = 1,
prior_num_inference_steps: int = 25,
decoder_num_inference_steps: int = 25,
super_res_num_inference_steps: int = 7,
generator: Optional[torch.Generator] = None,
prior_latents: Optional[torch.FloatTensor] = None,
decoder_latents: Optional[torch.FloatTensor] = None,
super_res_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,
output_type: Optional[str] = "pil",
return_dict: bool = True,
):
"""
Function invoked when calling the pipeline for generation.
Args:
prompt (`str` or `List[str]`):
The prompt or prompts to guide the image generation. This can only be left undefined if
`text_model_output` and `text_attention_mask` is passed.
num_images_per_prompt (`int`, *optional*, defaults to 1):
The number of images to generate per prompt.
prior_num_inference_steps (`int`, *optional*, defaults to 25):
The number of denoising steps for the prior. More denoising steps usually lead to a higher quality
image at the expense of slower inference.
decoder_num_inference_steps (`int`, *optional*, defaults to 25):
The number of denoising steps for the decoder. More denoising steps usually lead to a higher quality
image at the expense of slower inference.
super_res_num_inference_steps (`int`, *optional*, defaults to 7):
The number of denoising steps for super resolution. More denoising steps usually lead to a higher
quality image at the expense of slower inference.
generator (`torch.Generator`, *optional*):
One or a list of [torch generator(s)](https://pytorch.org/docs/stable/generated/torch.Generator.html)
to make generation deterministic.
prior_latents (`torch.FloatTensor` of shape (batch size, embeddings dimension), *optional*):
Pre-generated noisy latents to be used as inputs for the prior.
decoder_latents (`torch.FloatTensor` of shape (batch size, channels, height, width), *optional*):
Pre-generated noisy latents to be used as inputs for the decoder.
super_res_latents (`torch.FloatTensor` of shape (batch size, channels, super res height, super res width), *optional*):
Pre-generated noisy latents to be used as inputs for the decoder.
prior_guidance_scale (`float`, *optional*, defaults to 4.0):
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.
decoder_guidance_scale (`float`, *optional*, defaults to 4.0):
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.
text_model_output (`CLIPTextModelOutput`, *optional*):
Pre-defined CLIPTextModel outputs that can be derived from the text encoder. Pre-defined text outputs
can be passed for tasks like text embedding interpolations. Make sure to also pass
`text_attention_mask` in this case. `prompt` can the be left to `None`.
text_attention_mask (`torch.Tensor`, *optional*):
Pre-defined CLIP text attention mask that can be derived from the tokenizer. Pre-defined text attention
masks are necessary when passing `text_model_output`.
output_type (`str`, *optional*, defaults to `"pil"`):
The output format of the generated 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.ImagePipelineOutput`] instead of a plain tuple.
"""
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
# done prior
# decoder
text_encoder_hidden_states, additive_clip_time_embeddings = self.text_proj(
image_embeddings=image_embeddings,
text_embeddings=text_embeddings,
text_encoder_hidden_states=text_encoder_hidden_states,
do_classifier_free_guidance=do_classifier_free_guidance,
)
decoder_text_mask = F.pad(text_mask, (self.text_proj.clip_extra_context_tokens, 0), value=1)
self.decoder_scheduler.set_timesteps(decoder_num_inference_steps, device=device)
decoder_timesteps_tensor = self.decoder_scheduler.timesteps
num_channels_latents = self.decoder.in_channels
height = self.decoder.sample_size
width = self.decoder.sample_size
decoder_latents = self.prepare_latents(
(batch_size, num_channels_latents, height, width),
text_encoder_hidden_states.dtype,
device,
generator,
decoder_latents,
self.decoder_scheduler,
)
for i, t in enumerate(self.progress_bar(decoder_timesteps_tensor)):
# expand the latents if we are doing classifier free guidance
latent_model_input = torch.cat([decoder_latents] * 2) if do_classifier_free_guidance else decoder_latents
noise_pred = self.decoder(
sample=latent_model_input,
timestep=t,
encoder_hidden_states=text_encoder_hidden_states,
class_labels=additive_clip_time_embeddings,
attention_mask=decoder_text_mask,
).sample
if do_classifier_free_guidance:
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
noise_pred_uncond, _ = noise_pred_uncond.split(latent_model_input.shape[1], dim=1)
noise_pred_text, predicted_variance = noise_pred_text.split(latent_model_input.shape[1], dim=1)
noise_pred = noise_pred_uncond + decoder_guidance_scale * (noise_pred_text - noise_pred_uncond)
noise_pred = torch.cat([noise_pred, predicted_variance], dim=1)
if i + 1 == decoder_timesteps_tensor.shape[0]:
prev_timestep = None
else:
prev_timestep = decoder_timesteps_tensor[i + 1]
# compute the previous noisy sample x_t -> x_t-1
decoder_latents = self.decoder_scheduler.step(
noise_pred, t, decoder_latents, prev_timestep=prev_timestep, generator=generator
).prev_sample
decoder_latents = decoder_latents.clamp(-1, 1)
image_small = decoder_latents
# done decoder
# super res
self.super_res_scheduler.set_timesteps(super_res_num_inference_steps, device=device)
super_res_timesteps_tensor = self.super_res_scheduler.timesteps
channels = self.super_res_first.in_channels // 2
height = self.super_res_first.sample_size
width = self.super_res_first.sample_size
super_res_latents = self.prepare_latents(
(batch_size, channels, height, width),
image_small.dtype,
device,
generator,
super_res_latents,
self.super_res_scheduler,
)
interpolate_antialias = {}
if "antialias" in inspect.signature(F.interpolate).parameters:
interpolate_antialias["antialias"] = True
image_upscaled = F.interpolate(
image_small, size=[height, width], mode="bicubic", align_corners=False, **interpolate_antialias
)
for i, t in enumerate(self.progress_bar(super_res_timesteps_tensor)):
# no classifier free guidance
if i == super_res_timesteps_tensor.shape[0] - 1:
unet = self.super_res_last
else:
unet = self.super_res_first
latent_model_input = torch.cat([super_res_latents, image_upscaled], dim=1)
noise_pred = unet(
sample=latent_model_input,
timestep=t,
).sample
if i + 1 == super_res_timesteps_tensor.shape[0]:
prev_timestep = None
else:
prev_timestep = super_res_timesteps_tensor[i + 1]
# compute the previous noisy sample x_t -> x_t-1
super_res_latents = self.super_res_scheduler.step(
noise_pred, t, super_res_latents, prev_timestep=prev_timestep, generator=generator
).prev_sample
image = super_res_latents
# done super res
# post processing
image = image * 0.5 + 0.5
image = image.clamp(0, 1)
image = image.cpu().permute(0, 2, 3, 1).float().numpy()
if output_type == "pil":
image = self.numpy_to_pil(image)
if not return_dict:
return (image,)
return ImagePipelineOutput(images=image)