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pipeline_pndm.py
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pipeline_pndm.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.
from typing import List, Optional, Tuple, Union
import torch
from ...models import UNet2DModel
from ...schedulers import PNDMScheduler
from ...utils import randn_tensor
from ..pipeline_utils import DiffusionPipeline, ImagePipelineOutput
class PNDMPipeline(DiffusionPipeline):
r"""
Pipeline for unconditional image generation.
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:
unet ([`UNet2DModel`]):
A `UNet2DModel` to denoise the encoded image latents.
scheduler ([`PNDMScheduler`]):
A `PNDMScheduler` to be used in combination with `unet` to denoise the encoded image.
"""
unet: UNet2DModel
scheduler: PNDMScheduler
def __init__(self, unet: UNet2DModel, scheduler: PNDMScheduler):
super().__init__()
scheduler = PNDMScheduler.from_config(scheduler.config)
self.register_modules(unet=unet, scheduler=scheduler)
@torch.no_grad()
def __call__(
self,
batch_size: int = 1,
num_inference_steps: int = 50,
generator: Optional[Union[torch.Generator, List[torch.Generator]]] = None,
output_type: Optional[str] = "pil",
return_dict: bool = True,
**kwargs,
) -> Union[ImagePipelineOutput, Tuple]:
r"""
The call function to the pipeline for generation.
Args:
batch_size (`int`, `optional`, defaults to 1):
The number of images to generate.
num_inference_steps (`int`, `optional`, defaults to 50):
The number of denoising steps. More denoising steps usually lead to a higher quality image at the
expense of slower inference.
generator (`torch.Generator`, `optional`):
A [`torch.Generator`](https://pytorch.org/docs/stable/generated/torch.Generator.html) to make
generation deterministic.
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.
Example:
```py
>>> from diffusers import PNDMPipeline
>>> # load model and scheduler
>>> pndm = PNDMPipeline.from_pretrained("google/ddpm-cifar10-32")
>>> # run pipeline in inference (sample random noise and denoise)
>>> image = pndm().images[0]
>>> # save image
>>> image.save("pndm_generated_image.png")
```
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.
"""
# For more information on the sampling method you can take a look at Algorithm 2 of
# the official paper: https://arxiv.org/pdf/2202.09778.pdf
# Sample gaussian noise to begin loop
image = randn_tensor(
(batch_size, self.unet.config.in_channels, self.unet.config.sample_size, self.unet.config.sample_size),
generator=generator,
device=self.device,
)
self.scheduler.set_timesteps(num_inference_steps)
for t in self.progress_bar(self.scheduler.timesteps):
model_output = self.unet(image, t).sample
image = self.scheduler.step(model_output, t, image).prev_sample
image = (image / 2 + 0.5).clamp(0, 1)
image = image.cpu().permute(0, 2, 3, 1).numpy()
if output_type == "pil":
image = self.numpy_to_pil(image)
if not return_dict:
return (image,)
return ImagePipelineOutput(images=image)