Datasets:

ArXiv:
Diffusers Bot
Upload folder using huggingface_hub
916080e verified
raw
history blame
9.48 kB
from typing import Optional
import torch
from PIL import Image
from tqdm.auto import tqdm
from transformers import CLIPTextModel, CLIPTokenizer
from diffusers import AutoencoderKL, DDIMScheduler, DiffusionPipeline, UNet2DConditionModel
from diffusers.image_processor import VaeImageProcessor
from diffusers.utils import (
deprecate,
)
class EDICTPipeline(DiffusionPipeline):
def __init__(
self,
vae: AutoencoderKL,
text_encoder: CLIPTextModel,
tokenizer: CLIPTokenizer,
unet: UNet2DConditionModel,
scheduler: DDIMScheduler,
mixing_coeff: float = 0.93,
leapfrog_steps: bool = True,
):
self.mixing_coeff = mixing_coeff
self.leapfrog_steps = leapfrog_steps
super().__init__()
self.register_modules(
vae=vae,
text_encoder=text_encoder,
tokenizer=tokenizer,
unet=unet,
scheduler=scheduler,
)
self.vae_scale_factor = 2 ** (len(self.vae.config.block_out_channels) - 1)
self.image_processor = VaeImageProcessor(vae_scale_factor=self.vae_scale_factor)
def _encode_prompt(
self, prompt: str, negative_prompt: Optional[str] = None, do_classifier_free_guidance: bool = False
):
text_inputs = self.tokenizer(
prompt,
padding="max_length",
max_length=self.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
prompt_embeds = self.text_encoder(text_inputs.input_ids.to(self.device)).last_hidden_state
prompt_embeds = prompt_embeds.to(dtype=self.text_encoder.dtype, device=self.device)
if do_classifier_free_guidance:
uncond_tokens = "" if negative_prompt is None else negative_prompt
uncond_input = self.tokenizer(
uncond_tokens,
padding="max_length",
max_length=self.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
negative_prompt_embeds = self.text_encoder(uncond_input.input_ids.to(self.device)).last_hidden_state
prompt_embeds = torch.cat([negative_prompt_embeds, prompt_embeds])
return prompt_embeds
def denoise_mixing_layer(self, x: torch.Tensor, y: torch.Tensor):
x = self.mixing_coeff * x + (1 - self.mixing_coeff) * y
y = self.mixing_coeff * y + (1 - self.mixing_coeff) * x
return [x, y]
def noise_mixing_layer(self, x: torch.Tensor, y: torch.Tensor):
y = (y - (1 - self.mixing_coeff) * x) / self.mixing_coeff
x = (x - (1 - self.mixing_coeff) * y) / self.mixing_coeff
return [x, y]
def _get_alpha_and_beta(self, t: torch.Tensor):
# as self.alphas_cumprod is always in cpu
t = int(t)
alpha_prod = self.scheduler.alphas_cumprod[t] if t >= 0 else self.scheduler.final_alpha_cumprod
return alpha_prod, 1 - alpha_prod
def noise_step(
self,
base: torch.Tensor,
model_input: torch.Tensor,
model_output: torch.Tensor,
timestep: torch.Tensor,
):
prev_timestep = timestep - self.scheduler.config.num_train_timesteps / self.scheduler.num_inference_steps
alpha_prod_t, beta_prod_t = self._get_alpha_and_beta(timestep)
alpha_prod_t_prev, beta_prod_t_prev = self._get_alpha_and_beta(prev_timestep)
a_t = (alpha_prod_t_prev / alpha_prod_t) ** 0.5
b_t = -a_t * (beta_prod_t**0.5) + beta_prod_t_prev**0.5
next_model_input = (base - b_t * model_output) / a_t
return model_input, next_model_input.to(base.dtype)
def denoise_step(
self,
base: torch.Tensor,
model_input: torch.Tensor,
model_output: torch.Tensor,
timestep: torch.Tensor,
):
prev_timestep = timestep - self.scheduler.config.num_train_timesteps / self.scheduler.num_inference_steps
alpha_prod_t, beta_prod_t = self._get_alpha_and_beta(timestep)
alpha_prod_t_prev, beta_prod_t_prev = self._get_alpha_and_beta(prev_timestep)
a_t = (alpha_prod_t_prev / alpha_prod_t) ** 0.5
b_t = -a_t * (beta_prod_t**0.5) + beta_prod_t_prev**0.5
next_model_input = a_t * base + b_t * model_output
return model_input, next_model_input.to(base.dtype)
@torch.no_grad()
def decode_latents(self, latents: torch.Tensor):
latents = 1 / self.vae.config.scaling_factor * latents
image = self.vae.decode(latents).sample
image = (image / 2 + 0.5).clamp(0, 1)
return image
@torch.no_grad()
def prepare_latents(
self,
image: Image.Image,
text_embeds: torch.Tensor,
timesteps: torch.Tensor,
guidance_scale: float,
generator: Optional[torch.Generator] = None,
):
do_classifier_free_guidance = guidance_scale > 1.0
image = image.to(device=self.device, dtype=text_embeds.dtype)
latent = self.vae.encode(image).latent_dist.sample(generator)
latent = self.vae.config.scaling_factor * latent
coupled_latents = [latent.clone(), latent.clone()]
for i, t in tqdm(enumerate(timesteps), total=len(timesteps)):
coupled_latents = self.noise_mixing_layer(x=coupled_latents[0], y=coupled_latents[1])
# j - model_input index, k - base index
for j in range(2):
k = j ^ 1
if self.leapfrog_steps:
if i % 2 == 0:
k, j = j, k
model_input = coupled_latents[j]
base = coupled_latents[k]
latent_model_input = torch.cat([model_input] * 2) if do_classifier_free_guidance else model_input
noise_pred = self.unet(latent_model_input, t, encoder_hidden_states=text_embeds).sample
if do_classifier_free_guidance:
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
base, model_input = self.noise_step(
base=base,
model_input=model_input,
model_output=noise_pred,
timestep=t,
)
coupled_latents[k] = model_input
return coupled_latents
@torch.no_grad()
def __call__(
self,
base_prompt: str,
target_prompt: str,
image: Image.Image,
guidance_scale: float = 3.0,
num_inference_steps: int = 50,
strength: float = 0.8,
negative_prompt: Optional[str] = None,
generator: Optional[torch.Generator] = None,
output_type: Optional[str] = "pil",
):
do_classifier_free_guidance = guidance_scale > 1.0
image = self.image_processor.preprocess(image)
base_embeds = self._encode_prompt(base_prompt, negative_prompt, do_classifier_free_guidance)
target_embeds = self._encode_prompt(target_prompt, negative_prompt, do_classifier_free_guidance)
self.scheduler.set_timesteps(num_inference_steps, self.device)
t_limit = num_inference_steps - int(num_inference_steps * strength)
fwd_timesteps = self.scheduler.timesteps[t_limit:]
bwd_timesteps = fwd_timesteps.flip(0)
coupled_latents = self.prepare_latents(image, base_embeds, bwd_timesteps, guidance_scale, generator)
for i, t in tqdm(enumerate(fwd_timesteps), total=len(fwd_timesteps)):
# j - model_input index, k - base index
for k in range(2):
j = k ^ 1
if self.leapfrog_steps:
if i % 2 == 1:
k, j = j, k
model_input = coupled_latents[j]
base = coupled_latents[k]
latent_model_input = torch.cat([model_input] * 2) if do_classifier_free_guidance else model_input
noise_pred = self.unet(latent_model_input, t, encoder_hidden_states=target_embeds).sample
if do_classifier_free_guidance:
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
base, model_input = self.denoise_step(
base=base,
model_input=model_input,
model_output=noise_pred,
timestep=t,
)
coupled_latents[k] = model_input
coupled_latents = self.denoise_mixing_layer(x=coupled_latents[0], y=coupled_latents[1])
# either one is fine
final_latent = coupled_latents[0]
if output_type not in ["latent", "pt", "np", "pil"]:
deprecation_message = (
f"the output_type {output_type} is outdated. Please make sure to set it to one of these instead: "
"`pil`, `np`, `pt`, `latent`"
)
deprecate("Unsupported output_type", "1.0.0", deprecation_message, standard_warn=False)
output_type = "np"
if output_type == "latent":
image = final_latent
else:
image = self.decode_latents(final_latent)
image = self.image_processor.postprocess(image, output_type=output_type)
return image