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# Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
# William Peebles and Saining Xie
#
# Copyright (c) 2021 OpenAI
# MIT License
#
# 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.
from typing import Dict, List, Optional, Tuple, Union
import torch
from ...models import AutoencoderKL, Transformer2DModel
from ...schedulers import KarrasDiffusionSchedulers
from ...utils.torch_utils import randn_tensor
from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput
class DiTPipeline(DiffusionPipeline):
r"""
Pipeline for image generation based on a Transformer backbone instead of a UNet.
This model inherits from [`DiffusionPipeline`]. Check the superclass documentation for the generic methods
implemented for all pipelines (downloading, saving, running on a particular device, etc.).
Parameters:
transformer ([`Transformer2DModel`]):
A class conditioned `Transformer2DModel` to denoise the encoded image latents.
vae ([`AutoencoderKL`]):
Variational Auto-Encoder (VAE) model to encode and decode images to and from latent representations.
scheduler ([`DDIMScheduler`]):
A scheduler to be used in combination with `transformer` to denoise the encoded image latents.
"""
model_cpu_offload_seq = "transformer->vae"
def __init__(
self,
transformer: Transformer2DModel,
vae: AutoencoderKL,
scheduler: KarrasDiffusionSchedulers,
id2label: Optional[Dict[int, str]] = None,
):
super().__init__()
self.register_modules(transformer=transformer, vae=vae, scheduler=scheduler)
# create a imagenet -> id dictionary for easier use
self.labels = {}
if id2label is not None:
for key, value in id2label.items():
for label in value.split(","):
self.labels[label.lstrip().rstrip()] = int(key)
self.labels = dict(sorted(self.labels.items()))
def get_label_ids(self, label: Union[str, List[str]]) -> List[int]:
r"""
Map label strings from ImageNet to corresponding class ids.
Parameters:
label (`str` or `dict` of `str`):
Label strings to be mapped to class ids.
Returns:
`list` of `int`:
Class ids to be processed by pipeline.
"""
if not isinstance(label, list):
label = list(label)
for l in label:
if l not in self.labels:
raise ValueError(
f"{l} does not exist. Please make sure to select one of the following labels: \n {self.labels}."
)
return [self.labels[l] for l in label]
@torch.no_grad()
def __call__(
self,
class_labels: List[int],
guidance_scale: float = 4.0,
generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
num_inference_steps: int = 50,
output_type: Optional[str] = "pil",
return_dict: bool = True,
) -> Union[ImagePipelineOutput, Tuple]:
r"""
The call function to the pipeline for generation.
Args:
class_labels (List[int]):
List of ImageNet class labels for the images to be generated.
guidance_scale (`float`, *optional*, defaults to 4.0):
A higher guidance scale value encourages the model to generate images closely linked to the text
`prompt` at the expense of lower image quality. Guidance scale is enabled when `guidance_scale > 1`.
generator (`torch.Generator`, *optional*):
A [`torch.Generator`](https://pytorch.org/docs/stable/generated/torch.Generator.html) to make
generation deterministic.
num_inference_steps (`int`, *optional*, defaults to 250):
The number of denoising steps. More denoising steps usually lead to a higher quality image at the
expense of slower inference.
output_type (`str`, *optional*, defaults to `"pil"`):
The output format of the generated image. Choose between `PIL.Image` or `np.array`.
return_dict (`bool`, *optional*, defaults to `True`):
Whether or not to return a [`ImagePipelineOutput`] instead of a plain tuple.
Examples:
```py
>>> from diffusers import DiTPipeline, DPMSolverMultistepScheduler
>>> import torch
>>> pipe = DiTPipeline.from_pretrained("facebook/DiT-XL-2-256", torch_dtype=torch.float16)
>>> pipe.scheduler = DPMSolverMultistepScheduler.from_config(pipe.scheduler.config)
>>> pipe = pipe.to("cuda")
>>> # pick words from Imagenet class labels
>>> pipe.labels # to print all available words
>>> # pick words that exist in ImageNet
>>> words = ["white shark", "umbrella"]
>>> class_ids = pipe.get_label_ids(words)
>>> generator = torch.manual_seed(33)
>>> output = pipe(class_labels=class_ids, num_inference_steps=25, generator=generator)
>>> image = output.images[0] # label 'white shark'
```
Returns:
[`~pipelines.ImagePipelineOutput`] or `tuple`:
If `return_dict` is `True`, [`~pipelines.ImagePipelineOutput`] is returned, otherwise a `tuple` is
returned where the first element is a list with the generated images
"""
batch_size = len(class_labels)
latent_size = self.transformer.config.sample_size
latent_channels = self.transformer.config.in_channels
latents = randn_tensor(
shape=(batch_size, latent_channels, latent_size, latent_size),
generator=generator,
device=self._execution_device,
dtype=self.transformer.dtype,
)
latent_model_input = torch.cat([latents] * 2) if guidance_scale > 1 else latents
class_labels = torch.tensor(class_labels, device=self._execution_device).reshape(-1)
class_null = torch.tensor([1000] * batch_size, device=self._execution_device)
class_labels_input = torch.cat([class_labels, class_null], 0) if guidance_scale > 1 else class_labels
# set step values
self.scheduler.set_timesteps(num_inference_steps)
for t in self.progress_bar(self.scheduler.timesteps):
if guidance_scale > 1:
half = latent_model_input[: len(latent_model_input) // 2]
latent_model_input = torch.cat([half, half], dim=0)
latent_model_input = self.scheduler.scale_model_input(latent_model_input, t)
timesteps = t
if not torch.is_tensor(timesteps):
# TODO: this requires sync between CPU and GPU. So try to pass timesteps as tensors if you can
# This would be a good case for the `match` statement (Python 3.10+)
is_mps = latent_model_input.device.type == "mps"
if isinstance(timesteps, float):
dtype = torch.float32 if is_mps else torch.float64
else:
dtype = torch.int32 if is_mps else torch.int64
timesteps = torch.tensor([timesteps], dtype=dtype, device=latent_model_input.device)
elif len(timesteps.shape) == 0:
timesteps = timesteps[None].to(latent_model_input.device)
# broadcast to batch dimension in a way that's compatible with ONNX/Core ML
timesteps = timesteps.expand(latent_model_input.shape[0])
# predict noise model_output
noise_pred = self.transformer(
latent_model_input, timestep=timesteps, class_labels=class_labels_input
).sample
# perform guidance
if guidance_scale > 1:
eps, rest = noise_pred[:, :latent_channels], noise_pred[:, latent_channels:]
cond_eps, uncond_eps = torch.split(eps, len(eps) // 2, dim=0)
half_eps = uncond_eps + guidance_scale * (cond_eps - uncond_eps)
eps = torch.cat([half_eps, half_eps], dim=0)
noise_pred = torch.cat([eps, rest], dim=1)
# learned sigma
if self.transformer.config.out_channels // 2 == latent_channels:
model_output, _ = torch.split(noise_pred, latent_channels, dim=1)
else:
model_output = noise_pred
# compute previous image: x_t -> x_t-1
latent_model_input = self.scheduler.step(model_output, t, latent_model_input).prev_sample
if guidance_scale > 1:
latents, _ = latent_model_input.chunk(2, dim=0)
else:
latents = latent_model_input
latents = 1 / self.vae.config.scaling_factor * latents
samples = self.vae.decode(latents).sample
samples = (samples / 2 + 0.5).clamp(0, 1)
# we always cast to float32 as this does not cause significant overhead and is compatible with bfloat16
samples = samples.cpu().permute(0, 2, 3, 1).float().numpy()
if output_type == "pil":
samples = self.numpy_to_pil(samples)
if not return_dict:
return (samples,)
return ImagePipelineOutput(images=samples)
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