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# ref https://huggingface.co/spaces/editing-images/ledits/blob/main/inversion_utils.py
import torch
import os
from tqdm import tqdm
from toolkit import train_tools
from toolkit.prompt_utils import PromptEmbeds
from toolkit.stable_diffusion_model import StableDiffusion
def mu_tilde(model, xt, x0, timestep):
"mu_tilde(x_t, x_0) DDPM paper eq. 7"
prev_timestep = timestep - model.scheduler.config.num_train_timesteps // model.scheduler.num_inference_steps
alpha_prod_t_prev = model.scheduler.alphas_cumprod[
prev_timestep] if prev_timestep >= 0 else model.scheduler.final_alpha_cumprod
alpha_t = model.scheduler.alphas[timestep]
beta_t = 1 - alpha_t
alpha_bar = model.scheduler.alphas_cumprod[timestep]
return ((alpha_prod_t_prev ** 0.5 * beta_t) / (1 - alpha_bar)) * x0 + (
(alpha_t ** 0.5 * (1 - alpha_prod_t_prev)) / (1 - alpha_bar)) * xt
def sample_xts_from_x0(sd: StableDiffusion, sample: torch.Tensor, num_inference_steps=50):
"""
Samples from P(x_1:T|x_0)
"""
# torch.manual_seed(43256465436)
alpha_bar = sd.noise_scheduler.alphas_cumprod
sqrt_one_minus_alpha_bar = (1 - alpha_bar) ** 0.5
alphas = sd.noise_scheduler.alphas
betas = 1 - alphas
# variance_noise_shape = (
# num_inference_steps,
# sd.unet.in_channels,
# sd.unet.sample_size,
# sd.unet.sample_size)
variance_noise_shape = list(sample.shape)
variance_noise_shape[0] = num_inference_steps
timesteps = sd.noise_scheduler.timesteps.to(sd.device)
t_to_idx = {int(v): k for k, v in enumerate(timesteps)}
xts = torch.zeros(variance_noise_shape).to(sample.device, dtype=torch.float16)
for t in reversed(timesteps):
idx = t_to_idx[int(t)]
xts[idx] = sample * (alpha_bar[t] ** 0.5) + torch.randn_like(sample, dtype=torch.float16) * sqrt_one_minus_alpha_bar[t]
xts = torch.cat([xts, sample], dim=0)
return xts
def encode_text(model, prompts):
text_input = model.tokenizer(
prompts,
padding="max_length",
max_length=model.tokenizer.model_max_length,
truncation=True,
return_tensors="pt",
)
with torch.no_grad():
text_encoding = model.text_encoder(text_input.input_ids.to(model.device))[0]
return text_encoding
def forward_step(sd: StableDiffusion, model_output, timestep, sample):
next_timestep = min(
sd.noise_scheduler.config['num_train_timesteps'] - 2,
timestep + sd.noise_scheduler.config['num_train_timesteps'] // sd.noise_scheduler.num_inference_steps
)
# 2. compute alphas, betas
alpha_prod_t = sd.noise_scheduler.alphas_cumprod[timestep]
# alpha_prod_t_next = self.scheduler.alphas_cumprod[next_timestep] if next_ltimestep >= 0 else self.scheduler.final_alpha_cumprod
beta_prod_t = 1 - alpha_prod_t
# 3. compute predicted original sample from predicted noise also called
# "predicted x_0" of formula (12) from https://arxiv.org/pdf/2010.02502.pdf
pred_original_sample = (sample - beta_prod_t ** (0.5) * model_output) / alpha_prod_t ** (0.5)
# 5. TODO: simple noising implementation
next_sample = sd.noise_scheduler.add_noise(
pred_original_sample,
model_output,
torch.LongTensor([next_timestep]))
return next_sample
def get_variance(sd: StableDiffusion, timestep): # , prev_timestep):
prev_timestep = timestep - sd.noise_scheduler.config['num_train_timesteps'] // sd.noise_scheduler.num_inference_steps
alpha_prod_t = sd.noise_scheduler.alphas_cumprod[timestep]
alpha_prod_t_prev = sd.noise_scheduler.alphas_cumprod[
prev_timestep] if prev_timestep >= 0 else sd.noise_scheduler.final_alpha_cumprod
beta_prod_t = 1 - alpha_prod_t
beta_prod_t_prev = 1 - alpha_prod_t_prev
variance = (beta_prod_t_prev / beta_prod_t) * (1 - alpha_prod_t / alpha_prod_t_prev)
return variance
def get_time_ids_from_latents(sd: StableDiffusion, latents: torch.Tensor):
VAE_SCALE_FACTOR = 2 ** (len(sd.vae.config['block_out_channels']) - 1)
if sd.is_xl:
bs, ch, h, w = list(latents.shape)
height = h * VAE_SCALE_FACTOR
width = w * VAE_SCALE_FACTOR
dtype = latents.dtype
# just do it without any cropping nonsense
target_size = (height, width)
original_size = (height, width)
crops_coords_top_left = (0, 0)
add_time_ids = list(original_size + crops_coords_top_left + target_size)
add_time_ids = torch.tensor([add_time_ids])
add_time_ids = add_time_ids.to(latents.device, dtype=dtype)
batch_time_ids = torch.cat(
[add_time_ids for _ in range(bs)]
)
return batch_time_ids
else:
return None
def inversion_forward_process(
sd: StableDiffusion,
sample: torch.Tensor,
conditional_embeddings: PromptEmbeds,
unconditional_embeddings: PromptEmbeds,
etas=None,
prog_bar=False,
cfg_scale=3.5,
num_inference_steps=50, eps=None
):
current_num_timesteps = len(sd.noise_scheduler.timesteps)
sd.noise_scheduler.set_timesteps(num_inference_steps, device=sd.device)
timesteps = sd.noise_scheduler.timesteps.to(sd.device)
# variance_noise_shape = (
# num_inference_steps,
# sd.unet.in_channels,
# sd.unet.sample_size,
# sd.unet.sample_size
# )
variance_noise_shape = list(sample.shape)
variance_noise_shape[0] = num_inference_steps
if etas is None or (type(etas) in [int, float] and etas == 0):
eta_is_zero = True
zs = None
else:
eta_is_zero = False
if type(etas) in [int, float]: etas = [etas] * sd.noise_scheduler.num_inference_steps
xts = sample_xts_from_x0(sd, sample, num_inference_steps=num_inference_steps)
alpha_bar = sd.noise_scheduler.alphas_cumprod
zs = torch.zeros(size=variance_noise_shape, device=sd.device, dtype=torch.float16)
t_to_idx = {int(v): k for k, v in enumerate(timesteps)}
noisy_sample = sample
op = tqdm(reversed(timesteps), desc="Inverting...") if prog_bar else reversed(timesteps)
for timestep in op:
idx = t_to_idx[int(timestep)]
# 1. predict noise residual
if not eta_is_zero:
noisy_sample = xts[idx][None]
added_cond_kwargs = {}
with torch.no_grad():
text_embeddings = train_tools.concat_prompt_embeddings(
unconditional_embeddings, # negative embedding
conditional_embeddings, # positive embedding
1, # batch size
)
if sd.is_xl:
add_time_ids = get_time_ids_from_latents(sd, noisy_sample)
# add extra for cfg
add_time_ids = torch.cat(
[add_time_ids] * 2, dim=0
)
added_cond_kwargs = {
"text_embeds": text_embeddings.pooled_embeds,
"time_ids": add_time_ids,
}
# double up for cfg
latent_model_input = torch.cat(
[noisy_sample] * 2, dim=0
)
noise_pred = sd.unet(
latent_model_input,
timestep,
encoder_hidden_states=text_embeddings.text_embeds,
added_cond_kwargs=added_cond_kwargs,
).sample
noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
# out = sd.unet.forward(noisy_sample, timestep=timestep, encoder_hidden_states=uncond_embedding)
# cond_out = sd.unet.forward(noisy_sample, timestep=timestep, encoder_hidden_states=text_embeddings)
noise_pred = noise_pred_uncond + cfg_scale * (noise_pred_text - noise_pred_uncond)
if eta_is_zero:
# 2. compute more noisy image and set x_t -> x_t+1
noisy_sample = forward_step(sd, noise_pred, timestep, noisy_sample)
xts = None
else:
xtm1 = xts[idx + 1][None]
# pred of x0
pred_original_sample = (noisy_sample - (1 - alpha_bar[timestep]) ** 0.5 * noise_pred) / alpha_bar[
timestep] ** 0.5
# direction to xt
prev_timestep = timestep - sd.noise_scheduler.config[
'num_train_timesteps'] // sd.noise_scheduler.num_inference_steps
alpha_prod_t_prev = sd.noise_scheduler.alphas_cumprod[
prev_timestep] if prev_timestep >= 0 else sd.noise_scheduler.final_alpha_cumprod
variance = get_variance(sd, timestep)
pred_sample_direction = (1 - alpha_prod_t_prev - etas[idx] * variance) ** (0.5) * noise_pred
mu_xt = alpha_prod_t_prev ** (0.5) * pred_original_sample + pred_sample_direction
z = (xtm1 - mu_xt) / (etas[idx] * variance ** 0.5)
zs[idx] = z
# correction to avoid error accumulation
xtm1 = mu_xt + (etas[idx] * variance ** 0.5) * z
xts[idx + 1] = xtm1
if not zs is None:
zs[-1] = torch.zeros_like(zs[-1])
# restore timesteps
sd.noise_scheduler.set_timesteps(current_num_timesteps, device=sd.device)
return noisy_sample, zs, xts
#
# def inversion_forward_process(
# model,
# sample,
# etas=None,
# prog_bar=False,
# prompt="",
# cfg_scale=3.5,
# num_inference_steps=50, eps=None
# ):
# if not prompt == "":
# text_embeddings = encode_text(model, prompt)
# uncond_embedding = encode_text(model, "")
# timesteps = model.scheduler.timesteps.to(model.device)
# variance_noise_shape = (
# num_inference_steps,
# model.unet.in_channels,
# model.unet.sample_size,
# model.unet.sample_size)
# if etas is None or (type(etas) in [int, float] and etas == 0):
# eta_is_zero = True
# zs = None
# else:
# eta_is_zero = False
# if type(etas) in [int, float]: etas = [etas] * model.scheduler.num_inference_steps
# xts = sample_xts_from_x0(model, sample, num_inference_steps=num_inference_steps)
# alpha_bar = model.scheduler.alphas_cumprod
# zs = torch.zeros(size=variance_noise_shape, device=model.device, dtype=torch.float16)
#
# t_to_idx = {int(v): k for k, v in enumerate(timesteps)}
# noisy_sample = sample
# op = tqdm(reversed(timesteps), desc="Inverting...") if prog_bar else reversed(timesteps)
#
# for t in op:
# idx = t_to_idx[int(t)]
# # 1. predict noise residual
# if not eta_is_zero:
# noisy_sample = xts[idx][None]
#
# with torch.no_grad():
# out = model.unet.forward(noisy_sample, timestep=t, encoder_hidden_states=uncond_embedding)
# if not prompt == "":
# cond_out = model.unet.forward(noisy_sample, timestep=t, encoder_hidden_states=text_embeddings)
#
# if not prompt == "":
# ## classifier free guidance
# noise_pred = out.sample + cfg_scale * (cond_out.sample - out.sample)
# else:
# noise_pred = out.sample
#
# if eta_is_zero:
# # 2. compute more noisy image and set x_t -> x_t+1
# noisy_sample = forward_step(model, noise_pred, t, noisy_sample)
#
# else:
# xtm1 = xts[idx + 1][None]
# # pred of x0
# pred_original_sample = (noisy_sample - (1 - alpha_bar[t]) ** 0.5 * noise_pred) / alpha_bar[t] ** 0.5
#
# # direction to xt
# prev_timestep = t - model.scheduler.config.num_train_timesteps // model.scheduler.num_inference_steps
# alpha_prod_t_prev = model.scheduler.alphas_cumprod[
# prev_timestep] if prev_timestep >= 0 else model.scheduler.final_alpha_cumprod
#
# variance = get_variance(model, t)
# pred_sample_direction = (1 - alpha_prod_t_prev - etas[idx] * variance) ** (0.5) * noise_pred
#
# mu_xt = alpha_prod_t_prev ** (0.5) * pred_original_sample + pred_sample_direction
#
# z = (xtm1 - mu_xt) / (etas[idx] * variance ** 0.5)
# zs[idx] = z
#
# # correction to avoid error accumulation
# xtm1 = mu_xt + (etas[idx] * variance ** 0.5) * z
# xts[idx + 1] = xtm1
#
# if not zs is None:
# zs[-1] = torch.zeros_like(zs[-1])
#
# return noisy_sample, zs, xts
def reverse_step(model, model_output, timestep, sample, eta=0, variance_noise=None):
# 1. get previous step value (=t-1)
prev_timestep = timestep - model.scheduler.config.num_train_timesteps // model.scheduler.num_inference_steps
# 2. compute alphas, betas
alpha_prod_t = model.scheduler.alphas_cumprod[timestep]
alpha_prod_t_prev = model.scheduler.alphas_cumprod[
prev_timestep] if prev_timestep >= 0 else model.scheduler.final_alpha_cumprod
beta_prod_t = 1 - alpha_prod_t
# 3. compute predicted original sample from predicted noise also called
# "predicted x_0" of formula (12) from https://arxiv.org/pdf/2010.02502.pdf
pred_original_sample = (sample - beta_prod_t ** (0.5) * model_output) / alpha_prod_t ** (0.5)
# 5. compute variance: "sigma_t(η)" -> see formula (16)
# σ_t = sqrt((1 − α_t−1)/(1 − α_t)) * sqrt(1 − α_t/α_t−1)
# variance = self.scheduler._get_variance(timestep, prev_timestep)
variance = get_variance(model, timestep) # , prev_timestep)
std_dev_t = eta * variance ** (0.5)
# Take care of asymetric reverse process (asyrp)
model_output_direction = model_output
# 6. compute "direction pointing to x_t" of formula (12) from https://arxiv.org/pdf/2010.02502.pdf
# pred_sample_direction = (1 - alpha_prod_t_prev - std_dev_t**2) ** (0.5) * model_output_direction
pred_sample_direction = (1 - alpha_prod_t_prev - eta * variance) ** (0.5) * model_output_direction
# 7. compute x_t without "random noise" of formula (12) from https://arxiv.org/pdf/2010.02502.pdf
prev_sample = alpha_prod_t_prev ** (0.5) * pred_original_sample + pred_sample_direction
# 8. Add noice if eta > 0
if eta > 0:
if variance_noise is None:
variance_noise = torch.randn(model_output.shape, device=model.device, dtype=torch.float16)
sigma_z = eta * variance ** (0.5) * variance_noise
prev_sample = prev_sample + sigma_z
return prev_sample
def inversion_reverse_process(
model,
xT,
etas=0,
prompts="",
cfg_scales=None,
prog_bar=False,
zs=None,
controller=None,
asyrp=False):
batch_size = len(prompts)
cfg_scales_tensor = torch.Tensor(cfg_scales).view(-1, 1, 1, 1).to(model.device, dtype=torch.float16)
text_embeddings = encode_text(model, prompts)
uncond_embedding = encode_text(model, [""] * batch_size)
if etas is None: etas = 0
if type(etas) in [int, float]: etas = [etas] * model.scheduler.num_inference_steps
assert len(etas) == model.scheduler.num_inference_steps
timesteps = model.scheduler.timesteps.to(model.device)
xt = xT.expand(batch_size, -1, -1, -1)
op = tqdm(timesteps[-zs.shape[0]:]) if prog_bar else timesteps[-zs.shape[0]:]
t_to_idx = {int(v): k for k, v in enumerate(timesteps[-zs.shape[0]:])}
for t in op:
idx = t_to_idx[int(t)]
## Unconditional embedding
with torch.no_grad():
uncond_out = model.unet.forward(xt, timestep=t,
encoder_hidden_states=uncond_embedding)
## Conditional embedding
if prompts:
with torch.no_grad():
cond_out = model.unet.forward(xt, timestep=t,
encoder_hidden_states=text_embeddings)
z = zs[idx] if not zs is None else None
z = z.expand(batch_size, -1, -1, -1)
if prompts:
## classifier free guidance
noise_pred = uncond_out.sample + cfg_scales_tensor * (cond_out.sample - uncond_out.sample)
else:
noise_pred = uncond_out.sample
# 2. compute less noisy image and set x_t -> x_t-1
xt = reverse_step(model, noise_pred, t, xt, eta=etas[idx], variance_noise=z)
if controller is not None:
xt = controller.step_callback(xt)
return xt, zs
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