import torch
import argparse
import random
import re
from typing import List, Optional, Union
def prepare_scheduler_for_custom_training(noise_scheduler, device):
if hasattr(noise_scheduler, "all_snr"):
return
alphas_cumprod = noise_scheduler.alphas_cumprod
sqrt_alphas_cumprod = torch.sqrt(alphas_cumprod)
sqrt_one_minus_alphas_cumprod = torch.sqrt(1.0 - alphas_cumprod)
alpha = sqrt_alphas_cumprod
sigma = sqrt_one_minus_alphas_cumprod
all_snr = (alpha / sigma) ** 2
noise_scheduler.all_snr = all_snr.to(device)
def apply_snr_weight(loss, timesteps, noise_scheduler, gamma):
snr = torch.stack([noise_scheduler.all_snr[t] for t in timesteps])
gamma_over_snr = torch.div(torch.ones_like(snr) * gamma, snr)
snr_weight = torch.minimum(gamma_over_snr, torch.ones_like(gamma_over_snr)).float().to(loss.device) # from paper
loss = loss * snr_weight
return loss
def scale_v_prediction_loss_like_noise_prediction(loss, timesteps, noise_scheduler):
snr_t = torch.stack([noise_scheduler.all_snr[t] for t in timesteps]) # batch_size
snr_t = torch.minimum(snr_t, torch.ones_like(snr_t) * 1000) # if timestep is 0, snr_t is inf, so limit it to 1000
scale = snr_t / (snr_t + 1)
loss = loss * scale
return loss
# TODO train_utilと分散しているのでどちらかに寄せる
def add_custom_train_arguments(parser: argparse.ArgumentParser, support_weighted_captions: bool = True):
parser.add_argument(
"--min_snr_gamma",
type=float,
default=None,
help="gamma for reducing the weight of high loss timesteps. Lower numbers have stronger effect. 5 is recommended by paper. / 低いタイムステップでの高いlossに対して重みを減らすためのgamma値、低いほど効果が強く、論文では5が推奨",
)
parser.add_argument(
"--scale_v_pred_loss_like_noise_pred",
action="store_true",
help="scale v-prediction loss like noise prediction loss / v-prediction lossをnoise prediction lossと同じようにスケーリングする",
)
if support_weighted_captions:
parser.add_argument(
"--weighted_captions",
action="store_true",
default=False,
help="Enable weighted captions in the standard style (token:1.3). No commas inside parens, or shuffle/dropout may break the decoder. / 「[token]」、「(token)」「(token:1.3)」のような重み付きキャプションを有効にする。カンマを括弧内に入れるとシャッフルやdropoutで重みづけがおかしくなるので注意",
)
re_attention = re.compile(
r"""
\\\(|
\\\)|
\\\[|
\\]|
\\\\|
\\|
\(|
\[|
:([+-]?[.\d]+)\)|
\)|
]|
[^\\()\[\]:]+|
:
""",
re.X,
)
def parse_prompt_attention(text):
"""
Parses a string with attention tokens and returns a list of pairs: text and its associated weight.
Accepted tokens are:
(abc) - increases attention to abc by a multiplier of 1.1
(abc:3.12) - increases attention to abc by a multiplier of 3.12
[abc] - decreases attention to abc by a multiplier of 1.1
\( - literal character '('
\[ - literal character '['
\) - literal character ')'
\] - literal character ']'
\\ - literal character '\'
anything else - just text
>>> parse_prompt_attention('normal text')
[['normal text', 1.0]]
>>> parse_prompt_attention('an (important) word')
[['an ', 1.0], ['important', 1.1], [' word', 1.0]]
>>> parse_prompt_attention('(unbalanced')
[['unbalanced', 1.1]]
>>> parse_prompt_attention('\(literal\]')
[['(literal]', 1.0]]
>>> parse_prompt_attention('(unnecessary)(parens)')
[['unnecessaryparens', 1.1]]
>>> parse_prompt_attention('a (((house:1.3)) [on] a (hill:0.5), sun, (((sky))).')
[['a ', 1.0],
['house', 1.5730000000000004],
[' ', 1.1],
['on', 1.0],
[' a ', 1.1],
['hill', 0.55],
[', sun, ', 1.1],
['sky', 1.4641000000000006],
['.', 1.1]]
"""
res = []
round_brackets = []
square_brackets = []
round_bracket_multiplier = 1.1
square_bracket_multiplier = 1 / 1.1
def multiply_range(start_position, multiplier):
for p in range(start_position, len(res)):
res[p][1] *= multiplier
for m in re_attention.finditer(text):
text = m.group(0)
weight = m.group(1)
if text.startswith("\\"):
res.append([text[1:], 1.0])
elif text == "(":
round_brackets.append(len(res))
elif text == "[":
square_brackets.append(len(res))
elif weight is not None and len(round_brackets) > 0:
multiply_range(round_brackets.pop(), float(weight))
elif text == ")" and len(round_brackets) > 0:
multiply_range(round_brackets.pop(), round_bracket_multiplier)
elif text == "]" and len(square_brackets) > 0:
multiply_range(square_brackets.pop(), square_bracket_multiplier)
else:
res.append([text, 1.0])
for pos in round_brackets:
multiply_range(pos, round_bracket_multiplier)
for pos in square_brackets:
multiply_range(pos, square_bracket_multiplier)
if len(res) == 0:
res = [["", 1.0]]
# merge runs of identical weights
i = 0
while i + 1 < len(res):
if res[i][1] == res[i + 1][1]:
res[i][0] += res[i + 1][0]
res.pop(i + 1)
else:
i += 1
return res
def get_prompts_with_weights(tokenizer, prompt: List[str], max_length: int):
r"""
Tokenize a list of prompts and return its tokens with weights of each token.
No padding, starting or ending token is included.
"""
tokens = []
weights = []
truncated = False
for text in prompt:
texts_and_weights = parse_prompt_attention(text)
text_token = []
text_weight = []
for word, weight in texts_and_weights:
# tokenize and discard the starting and the ending token
token = tokenizer(word).input_ids[1:-1]
text_token += token
# copy the weight by length of token
text_weight += [weight] * len(token)
# stop if the text is too long (longer than truncation limit)
if len(text_token) > max_length:
truncated = True
break
# truncate
if len(text_token) > max_length:
truncated = True
text_token = text_token[:max_length]
text_weight = text_weight[:max_length]
tokens.append(text_token)
weights.append(text_weight)
if truncated:
print("Prompt was truncated. Try to shorten the prompt or increase max_embeddings_multiples")
return tokens, weights
def pad_tokens_and_weights(tokens, weights, max_length, bos, eos, no_boseos_middle=True, chunk_length=77):
r"""
Pad the tokens (with starting and ending tokens) and weights (with 1.0) to max_length.
"""
max_embeddings_multiples = (max_length - 2) // (chunk_length - 2)
weights_length = max_length if no_boseos_middle else max_embeddings_multiples * chunk_length
for i in range(len(tokens)):
tokens[i] = [bos] + tokens[i] + [eos] * (max_length - 1 - len(tokens[i]))
if no_boseos_middle:
weights[i] = [1.0] + weights[i] + [1.0] * (max_length - 1 - len(weights[i]))
else:
w = []
if len(weights[i]) == 0:
w = [1.0] * weights_length
else:
for j in range(max_embeddings_multiples):
w.append(1.0) # weight for starting token in this chunk
w += weights[i][j * (chunk_length - 2) : min(len(weights[i]), (j + 1) * (chunk_length - 2))]
w.append(1.0) # weight for ending token in this chunk
w += [1.0] * (weights_length - len(w))
weights[i] = w[:]
return tokens, weights
def get_unweighted_text_embeddings(
tokenizer,
text_encoder,
text_input: torch.Tensor,
chunk_length: int,
clip_skip: int,
eos: int,
pad: int,
no_boseos_middle: Optional[bool] = True,
):
"""
When the length of tokens is a multiple of the capacity of the text encoder,
it should be split into chunks and sent to the text encoder individually.
"""
max_embeddings_multiples = (text_input.shape[1] - 2) // (chunk_length - 2)
if max_embeddings_multiples > 1:
text_embeddings = []
for i in range(max_embeddings_multiples):
# extract the i-th chunk
text_input_chunk = text_input[:, i * (chunk_length - 2) : (i + 1) * (chunk_length - 2) + 2].clone()
# cover the head and the tail by the starting and the ending tokens
text_input_chunk[:, 0] = text_input[0, 0]
if pad == eos: # v1
text_input_chunk[:, -1] = text_input[0, -1]
else: # v2
for j in range(len(text_input_chunk)):
if text_input_chunk[j, -1] != eos and text_input_chunk[j, -1] != pad: # 最後に普通の文字がある
text_input_chunk[j, -1] = eos
if text_input_chunk[j, 1] == pad: # BOSだけであとはPAD
text_input_chunk[j, 1] = eos
if clip_skip is None or clip_skip == 1:
text_embedding = text_encoder(text_input_chunk)[0]
else:
enc_out = text_encoder(text_input_chunk, output_hidden_states=True, return_dict=True)
text_embedding = enc_out["hidden_states"][-clip_skip]
text_embedding = text_encoder.text_model.final_layer_norm(text_embedding)
if no_boseos_middle:
if i == 0:
# discard the ending token
text_embedding = text_embedding[:, :-1]
elif i == max_embeddings_multiples - 1:
# discard the starting token
text_embedding = text_embedding[:, 1:]
else:
# discard both starting and ending tokens
text_embedding = text_embedding[:, 1:-1]
text_embeddings.append(text_embedding)
text_embeddings = torch.concat(text_embeddings, axis=1)
else:
if clip_skip is None or clip_skip == 1:
text_embeddings = text_encoder(text_input)[0]
else:
enc_out = text_encoder(text_input, output_hidden_states=True, return_dict=True)
text_embeddings = enc_out["hidden_states"][-clip_skip]
text_embeddings = text_encoder.text_model.final_layer_norm(text_embeddings)
return text_embeddings
def get_weighted_text_embeddings(
tokenizer,
text_encoder,
prompt: Union[str, List[str]],
device,
max_embeddings_multiples: Optional[int] = 3,
no_boseos_middle: Optional[bool] = False,
clip_skip=None,
):
r"""
Prompts can be assigned with local weights using brackets. For example,
prompt 'A (very beautiful) masterpiece' highlights the words 'very beautiful',
and the embedding tokens corresponding to the words get multiplied by a constant, 1.1.
Also, to regularize of the embedding, the weighted embedding would be scaled to preserve the original mean.
Args:
prompt (`str` or `List[str]`):
The prompt or prompts to guide the image generation.
max_embeddings_multiples (`int`, *optional*, defaults to `3`):
The max multiple length of prompt embeddings compared to the max output length of text encoder.
no_boseos_middle (`bool`, *optional*, defaults to `False`):
If the length of text token is multiples of the capacity of text encoder, whether reserve the starting and
ending token in each of the chunk in the middle.
skip_parsing (`bool`, *optional*, defaults to `False`):
Skip the parsing of brackets.
skip_weighting (`bool`, *optional*, defaults to `False`):
Skip the weighting. When the parsing is skipped, it is forced True.
"""
max_length = (tokenizer.model_max_length - 2) * max_embeddings_multiples + 2
if isinstance(prompt, str):
prompt = [prompt]
prompt_tokens, prompt_weights = get_prompts_with_weights(tokenizer, prompt, max_length - 2)
# round up the longest length of tokens to a multiple of (model_max_length - 2)
max_length = max([len(token) for token in prompt_tokens])
max_embeddings_multiples = min(
max_embeddings_multiples,
(max_length - 1) // (tokenizer.model_max_length - 2) + 1,
)
max_embeddings_multiples = max(1, max_embeddings_multiples)
max_length = (tokenizer.model_max_length - 2) * max_embeddings_multiples + 2
# pad the length of tokens and weights
bos = tokenizer.bos_token_id
eos = tokenizer.eos_token_id
pad = tokenizer.pad_token_id
prompt_tokens, prompt_weights = pad_tokens_and_weights(
prompt_tokens,
prompt_weights,
max_length,
bos,
eos,
no_boseos_middle=no_boseos_middle,
chunk_length=tokenizer.model_max_length,
)
prompt_tokens = torch.tensor(prompt_tokens, dtype=torch.long, device=device)
# get the embeddings
text_embeddings = get_unweighted_text_embeddings(
tokenizer,
text_encoder,
prompt_tokens,
tokenizer.model_max_length,
clip_skip,
eos,
pad,
no_boseos_middle=no_boseos_middle,
)
prompt_weights = torch.tensor(prompt_weights, dtype=text_embeddings.dtype, device=device)
# assign weights to the prompts and normalize in the sense of mean
previous_mean = text_embeddings.float().mean(axis=[-2, -1]).to(text_embeddings.dtype)
text_embeddings = text_embeddings * prompt_weights.unsqueeze(-1)
current_mean = text_embeddings.float().mean(axis=[-2, -1]).to(text_embeddings.dtype)
text_embeddings = text_embeddings * (previous_mean / current_mean).unsqueeze(-1).unsqueeze(-1)
return text_embeddings
# https://wandb.ai/johnowhitaker/multires_noise/reports/Multi-Resolution-Noise-for-Diffusion-Model-Training--VmlldzozNjYyOTU2
def pyramid_noise_like(noise, device, iterations=6, discount=0.4):
b, c, w, h = noise.shape # EDIT: w and h get over-written, rename for a different variant!
u = torch.nn.Upsample(size=(w, h), mode="bilinear").to(device)
for i in range(iterations):
r = random.random() * 2 + 2 # Rather than always going 2x,
wn, hn = max(1, int(w / (r**i))), max(1, int(h / (r**i)))
noise += u(torch.randn(b, c, wn, hn).to(device)) * discount**i
if wn == 1 or hn == 1:
break # Lowest resolution is 1x1
return noise / noise.std() # Scaled back to roughly unit variance
# https://www.crosslabs.org//blog/diffusion-with-offset-noise
def apply_noise_offset(latents, noise, noise_offset, adaptive_noise_scale):
if noise_offset is None:
return noise
if adaptive_noise_scale is not None:
# latent shape: (batch_size, channels, height, width)
# abs mean value for each channel
latent_mean = torch.abs(latents.mean(dim=(2, 3), keepdim=True))
# multiply adaptive noise scale to the mean value and add it to the noise offset
noise_offset = noise_offset + adaptive_noise_scale * latent_mean
noise_offset = torch.clamp(noise_offset, 0.0, None) # in case of adaptive noise scale is negative
noise = noise + noise_offset * torch.randn((latents.shape[0], latents.shape[1], 1, 1), device=latents.device)
return noise
"""
##########################################
# Perlin Noise
def rand_perlin_2d(device, shape, res, fade=lambda t: 6 * t**5 - 15 * t**4 + 10 * t**3):
delta = (res[0] / shape[0], res[1] / shape[1])
d = (shape[0] // res[0], shape[1] // res[1])
grid = (
torch.stack(
torch.meshgrid(torch.arange(0, res[0], delta[0], device=device), torch.arange(0, res[1], delta[1], device=device)),
dim=-1,
)
% 1
)
angles = 2 * torch.pi * torch.rand(res[0] + 1, res[1] + 1, device=device)
gradients = torch.stack((torch.cos(angles), torch.sin(angles)), dim=-1)
tile_grads = (
lambda slice1, slice2: gradients[slice1[0] : slice1[1], slice2[0] : slice2[1]]
.repeat_interleave(d[0], 0)
.repeat_interleave(d[1], 1)
)
dot = lambda grad, shift: (
torch.stack((grid[: shape[0], : shape[1], 0] + shift[0], grid[: shape[0], : shape[1], 1] + shift[1]), dim=-1)
* grad[: shape[0], : shape[1]]
).sum(dim=-1)
n00 = dot(tile_grads([0, -1], [0, -1]), [0, 0])
n10 = dot(tile_grads([1, None], [0, -1]), [-1, 0])
n01 = dot(tile_grads([0, -1], [1, None]), [0, -1])
n11 = dot(tile_grads([1, None], [1, None]), [-1, -1])
t = fade(grid[: shape[0], : shape[1]])
return 1.414 * torch.lerp(torch.lerp(n00, n10, t[..., 0]), torch.lerp(n01, n11, t[..., 0]), t[..., 1])
def rand_perlin_2d_octaves(device, shape, res, octaves=1, persistence=0.5):
noise = torch.zeros(shape, device=device)
frequency = 1
amplitude = 1
for _ in range(octaves):
noise += amplitude * rand_perlin_2d(device, shape, (frequency * res[0], frequency * res[1]))
frequency *= 2
amplitude *= persistence
return noise
def perlin_noise(noise, device, octaves):
_, c, w, h = noise.shape
perlin = lambda: rand_perlin_2d_octaves(device, (w, h), (4, 4), octaves)
noise_perlin = []
for _ in range(c):
noise_perlin.append(perlin())
noise_perlin = torch.stack(noise_perlin).unsqueeze(0) # (1, c, w, h)
noise += noise_perlin # broadcast for each batch
return noise / noise.std() # Scaled back to roughly unit variance
"""