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import os
import imageio
import numpy as np
from typing import Union
import torch
import torchvision
from tqdm import tqdm
from einops import rearrange
import PIL.Image
import PIL.ImageOps
from packaging import version
from PIL import Image
def save_videos_grid(videos: torch.Tensor, path: str, rescale=False, n_rows=6, fps=8):
videos = rearrange(videos, "b c t h w -> t b c h w")
outputs = []
for x in videos:
x = torchvision.utils.make_grid(x, nrow=n_rows)
x = x.transpose(0, 1).transpose(1, 2).squeeze(-1)
if rescale:
x = (x + 1.0) / 2.0 # -1,1 -> 0,1
x = (x * 255).numpy().astype(np.uint8)
outputs.append(x)
os.makedirs(os.path.dirname(path), exist_ok=True)
imageio.mimsave(path, outputs, fps=fps)
# DDIM Inversion
@torch.no_grad()
def init_prompt(prompt, pipeline):
uncond_input = pipeline.tokenizer(
[""], padding="max_length", max_length=pipeline.tokenizer.model_max_length,
return_tensors="pt"
)
uncond_embeddings = pipeline.text_encoder(uncond_input.input_ids.to(pipeline.device))[0]
text_input = pipeline.tokenizer(
[prompt],
padding="max_length",
max_length=pipeline.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
text_embeddings = pipeline.text_encoder(text_input.input_ids.to(pipeline.device))[0]
context = torch.cat([uncond_embeddings, text_embeddings])
return context
def next_step(model_output: Union[torch.FloatTensor, np.ndarray], timestep: int,
sample: Union[torch.FloatTensor, np.ndarray], ddim_scheduler):
timestep, next_timestep = min(
timestep - ddim_scheduler.config.num_train_timesteps // ddim_scheduler.num_inference_steps, 999), timestep
alpha_prod_t = ddim_scheduler.alphas_cumprod[timestep] if timestep >= 0 else ddim_scheduler.final_alpha_cumprod
alpha_prod_t_next = ddim_scheduler.alphas_cumprod[next_timestep]
beta_prod_t = 1 - alpha_prod_t
next_original_sample = (sample - beta_prod_t ** 0.5 * model_output) / alpha_prod_t ** 0.5
next_sample_direction = (1 - alpha_prod_t_next) ** 0.5 * model_output
next_sample = alpha_prod_t_next ** 0.5 * next_original_sample + next_sample_direction
return next_sample
def get_noise_pred_single(latents, t, context, unet):
noise_pred = unet(latents, t, encoder_hidden_states=context)["sample"]
return noise_pred
@torch.no_grad()
def ddim_loop(pipeline, ddim_scheduler, latent, num_inv_steps, prompt):
context = init_prompt(prompt, pipeline)
uncond_embeddings, cond_embeddings = context.chunk(2)
all_latent = [latent]
latent = latent.clone().detach()
for i in tqdm(range(num_inv_steps)):
t = ddim_scheduler.timesteps[len(ddim_scheduler.timesteps) - i - 1]
noise_pred = get_noise_pred_single(latent, t, cond_embeddings, pipeline.unet)
latent = next_step(noise_pred, t, latent, ddim_scheduler)
all_latent.append(latent)
return all_latent
@torch.no_grad()
def ddim_inversion(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt=""):
ddim_latents = ddim_loop(pipeline, ddim_scheduler, video_latent, num_inv_steps, prompt)
return ddim_latents
if version.parse(version.parse(PIL.__version__).base_version) >= version.parse("9.1.0"):
PIL_INTERPOLATION = {
"linear": PIL.Image.Resampling.BILINEAR,
"bilinear": PIL.Image.Resampling.BILINEAR,
"bicubic": PIL.Image.Resampling.BICUBIC,
"lanczos": PIL.Image.Resampling.LANCZOS,
"nearest": PIL.Image.Resampling.NEAREST,
}
else:
PIL_INTERPOLATION = {
"linear": PIL.Image.LINEAR,
"bilinear": PIL.Image.BILINEAR,
"bicubic": PIL.Image.BICUBIC,
"lanczos": PIL.Image.LANCZOS,
"nearest": PIL.Image.NEAREST,
}
def pt_to_pil(images):
"""
Convert a torch image to a PIL image.
"""
images = (images / 2 + 0.5).clamp(0, 1)
images = images.cpu().permute(0, 2, 3, 1).float().numpy()
images = numpy_to_pil(images)
return images
def numpy_to_pil(images):
"""
Convert a numpy image or a batch of images to a PIL image.
"""
if images.ndim == 3:
images = images[None, ...]
images = (images * 255).round().astype("uint8")
if images.shape[-1] == 1:
# special case for grayscale (single channel) images
pil_images = [Image.fromarray(image.squeeze(), mode="L") for image in images]
else:
pil_images = [Image.fromarray(image) for image in images]
def preprocess_image(image):
if isinstance(image, torch.Tensor):
return image
elif isinstance(image, PIL.Image.Image):
image = [image]
if isinstance(image[0], PIL.Image.Image):
w, h = image[0].size
w, h = map(lambda x: x - x % 8, (w, h)) # resize to integer multiple of 8
image = [np.array(i.resize((w, h), resample=PIL_INTERPOLATION["lanczos"]))[None, :] for i in image]
image = np.concatenate(image, axis=0)
image = np.array(image).astype(np.float32) / 255.0
image = image.transpose(0, 3, 1, 2)
image = 2.0 * image - 1.0
image = torch.from_numpy(image)
elif isinstance(image[0], torch.Tensor):
image = torch.cat(image, dim=0)
return image |