File size: 4,865 Bytes
19a3d17 |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 |
from typing import Union
import torch
from PIL import Image
from torchvision import transforms as tfms
from tqdm.auto import tqdm
from transformers import CLIPTextModel, CLIPTokenizer
from diffusers import (
AutoencoderKL,
DDIMScheduler,
DiffusionPipeline,
LMSDiscreteScheduler,
PNDMScheduler,
UNet2DConditionModel,
)
class MagicMixPipeline(DiffusionPipeline):
def __init__(
self,
vae: AutoencoderKL,
text_encoder: CLIPTextModel,
tokenizer: CLIPTokenizer,
unet: UNet2DConditionModel,
scheduler: Union[PNDMScheduler, LMSDiscreteScheduler, DDIMScheduler],
):
super().__init__()
self.register_modules(vae=vae, text_encoder=text_encoder, tokenizer=tokenizer, unet=unet, scheduler=scheduler)
# convert PIL image to latents
def encode(self, img):
with torch.no_grad():
latent = self.vae.encode(tfms.ToTensor()(img).unsqueeze(0).to(self.device) * 2 - 1)
latent = 0.18215 * latent.latent_dist.sample()
return latent
# convert latents to PIL image
def decode(self, latent):
latent = (1 / 0.18215) * latent
with torch.no_grad():
img = self.vae.decode(latent).sample
img = (img / 2 + 0.5).clamp(0, 1)
img = img.detach().cpu().permute(0, 2, 3, 1).numpy()
img = (img * 255).round().astype("uint8")
return Image.fromarray(img[0])
# convert prompt into text embeddings, also unconditional embeddings
def prep_text(self, prompt):
text_input = self.tokenizer(
prompt,
padding="max_length",
max_length=self.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
text_embedding = self.text_encoder(text_input.input_ids.to(self.device))[0]
uncond_input = self.tokenizer(
"",
padding="max_length",
max_length=self.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
uncond_embedding = self.text_encoder(uncond_input.input_ids.to(self.device))[0]
return torch.cat([uncond_embedding, text_embedding])
def __call__(
self,
img: Image.Image,
prompt: str,
kmin: float = 0.3,
kmax: float = 0.6,
mix_factor: float = 0.5,
seed: int = 42,
steps: int = 50,
guidance_scale: float = 7.5,
) -> Image.Image:
tmin = steps - int(kmin * steps)
tmax = steps - int(kmax * steps)
text_embeddings = self.prep_text(prompt)
self.scheduler.set_timesteps(steps)
width, height = img.size
encoded = self.encode(img)
torch.manual_seed(seed)
noise = torch.randn(
(1, self.unet.config.in_channels, height // 8, width // 8),
).to(self.device)
latents = self.scheduler.add_noise(
encoded,
noise,
timesteps=self.scheduler.timesteps[tmax],
)
input = torch.cat([latents] * 2)
input = self.scheduler.scale_model_input(input, self.scheduler.timesteps[tmax])
with torch.no_grad():
pred = self.unet(
input,
self.scheduler.timesteps[tmax],
encoder_hidden_states=text_embeddings,
).sample
pred_uncond, pred_text = pred.chunk(2)
pred = pred_uncond + guidance_scale * (pred_text - pred_uncond)
latents = self.scheduler.step(pred, self.scheduler.timesteps[tmax], latents).prev_sample
for i, t in enumerate(tqdm(self.scheduler.timesteps)):
if i > tmax:
if i < tmin: # layout generation phase
orig_latents = self.scheduler.add_noise(
encoded,
noise,
timesteps=t,
)
input = (
(mix_factor * latents) + (1 - mix_factor) * orig_latents
) # interpolating between layout noise and conditionally generated noise to preserve layout sematics
input = torch.cat([input] * 2)
else: # content generation phase
input = torch.cat([latents] * 2)
input = self.scheduler.scale_model_input(input, t)
with torch.no_grad():
pred = self.unet(
input,
t,
encoder_hidden_states=text_embeddings,
).sample
pred_uncond, pred_text = pred.chunk(2)
pred = pred_uncond + guidance_scale * (pred_text - pred_uncond)
latents = self.scheduler.step(pred, t, latents).prev_sample
return self.decode(latents)
|