Upload extensions_built_in/diffusion_models/hidream/src/schedulers/flash_flow_match.py with huggingface_hub
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extensions_built_in/diffusion_models/hidream/src/schedulers/flash_flow_match.py
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| 1 |
+
# Copyright 2024 Stability AI, Katherine Crowson and The HuggingFace Team. All rights reserved.
|
| 2 |
+
#
|
| 3 |
+
# Licensed under the Apache License, Version 2.0 (the "License");
|
| 4 |
+
# you may not use this file except in compliance with the License.
|
| 5 |
+
# You may obtain a copy of the License at
|
| 6 |
+
#
|
| 7 |
+
# http://www.apache.org/licenses/LICENSE-2.0
|
| 8 |
+
#
|
| 9 |
+
# Unless required by applicable law or agreed to in writing, software
|
| 10 |
+
# distributed under the License is distributed on an "AS IS" BASIS,
|
| 11 |
+
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
| 12 |
+
# See the License for the specific language governing permissions and
|
| 13 |
+
# limitations under the License.
|
| 14 |
+
|
| 15 |
+
import math
|
| 16 |
+
from dataclasses import dataclass
|
| 17 |
+
from typing import List, Optional, Tuple, Union
|
| 18 |
+
|
| 19 |
+
import numpy as np
|
| 20 |
+
import torch
|
| 21 |
+
from diffusers.configuration_utils import ConfigMixin, register_to_config
|
| 22 |
+
from diffusers.schedulers.scheduling_utils import SchedulerMixin
|
| 23 |
+
from diffusers.utils import BaseOutput, is_scipy_available, logging
|
| 24 |
+
from diffusers.utils.torch_utils import randn_tensor
|
| 25 |
+
|
| 26 |
+
if is_scipy_available():
|
| 27 |
+
import scipy.stats
|
| 28 |
+
|
| 29 |
+
logger = logging.get_logger(__name__) # pylint: disable=invalid-name
|
| 30 |
+
|
| 31 |
+
|
| 32 |
+
@dataclass
|
| 33 |
+
class FlashFlowMatchEulerDiscreteSchedulerOutput(BaseOutput):
|
| 34 |
+
"""
|
| 35 |
+
Output class for the scheduler's `step` function output.
|
| 36 |
+
|
| 37 |
+
Args:
|
| 38 |
+
prev_sample (`torch.FloatTensor` of shape `(batch_size, num_channels, height, width)` for images):
|
| 39 |
+
Computed sample `(x_{t-1})` of previous timestep. `prev_sample` should be used as next model input in the
|
| 40 |
+
denoising loop.
|
| 41 |
+
"""
|
| 42 |
+
|
| 43 |
+
prev_sample: torch.FloatTensor
|
| 44 |
+
|
| 45 |
+
|
| 46 |
+
class FlashFlowMatchEulerDiscreteScheduler(SchedulerMixin, ConfigMixin):
|
| 47 |
+
"""
|
| 48 |
+
Euler scheduler.
|
| 49 |
+
|
| 50 |
+
This model inherits from [`SchedulerMixin`] and [`ConfigMixin`]. Check the superclass documentation for the generic
|
| 51 |
+
methods the library implements for all schedulers such as loading and saving.
|
| 52 |
+
|
| 53 |
+
Args:
|
| 54 |
+
num_train_timesteps (`int`, defaults to 1000):
|
| 55 |
+
The number of diffusion steps to train the model.
|
| 56 |
+
timestep_spacing (`str`, defaults to `"linspace"`):
|
| 57 |
+
The way the timesteps should be scaled. Refer to Table 2 of the [Common Diffusion Noise Schedules and
|
| 58 |
+
Sample Steps are Flawed](https://huggingface.co/papers/2305.08891) for more information.
|
| 59 |
+
shift (`float`, defaults to 1.0):
|
| 60 |
+
The shift value for the timestep schedule.
|
| 61 |
+
"""
|
| 62 |
+
|
| 63 |
+
_compatibles = []
|
| 64 |
+
order = 1
|
| 65 |
+
|
| 66 |
+
@register_to_config
|
| 67 |
+
def __init__(
|
| 68 |
+
self,
|
| 69 |
+
num_train_timesteps: int = 1000,
|
| 70 |
+
shift: float = 1.0,
|
| 71 |
+
use_dynamic_shifting=False,
|
| 72 |
+
base_shift: Optional[float] = 0.5,
|
| 73 |
+
max_shift: Optional[float] = 1.15,
|
| 74 |
+
base_image_seq_len: Optional[int] = 256,
|
| 75 |
+
max_image_seq_len: Optional[int] = 4096,
|
| 76 |
+
invert_sigmas: bool = False,
|
| 77 |
+
use_karras_sigmas: Optional[bool] = False,
|
| 78 |
+
use_exponential_sigmas: Optional[bool] = False,
|
| 79 |
+
use_beta_sigmas: Optional[bool] = False,
|
| 80 |
+
):
|
| 81 |
+
if self.config.use_beta_sigmas and not is_scipy_available():
|
| 82 |
+
raise ImportError("Make sure to install scipy if you want to use beta sigmas.")
|
| 83 |
+
if sum([self.config.use_beta_sigmas, self.config.use_exponential_sigmas, self.config.use_karras_sigmas]) > 1:
|
| 84 |
+
raise ValueError(
|
| 85 |
+
"Only one of `config.use_beta_sigmas`, `config.use_exponential_sigmas`, `config.use_karras_sigmas` can be used."
|
| 86 |
+
)
|
| 87 |
+
timesteps = np.linspace(1, num_train_timesteps, num_train_timesteps, dtype=np.float32)[::-1].copy()
|
| 88 |
+
timesteps = torch.from_numpy(timesteps).to(dtype=torch.float32)
|
| 89 |
+
|
| 90 |
+
sigmas = timesteps / num_train_timesteps
|
| 91 |
+
if not use_dynamic_shifting:
|
| 92 |
+
# when use_dynamic_shifting is True, we apply the timestep shifting on the fly based on the image resolution
|
| 93 |
+
sigmas = shift * sigmas / (1 + (shift - 1) * sigmas)
|
| 94 |
+
|
| 95 |
+
self.timesteps = sigmas * num_train_timesteps
|
| 96 |
+
|
| 97 |
+
self._step_index = None
|
| 98 |
+
self._begin_index = None
|
| 99 |
+
|
| 100 |
+
self.sigmas = sigmas.to("cpu") # to avoid too much CPU/GPU communication
|
| 101 |
+
self.sigma_min = self.sigmas[-1].item()
|
| 102 |
+
self.sigma_max = self.sigmas[0].item()
|
| 103 |
+
|
| 104 |
+
@property
|
| 105 |
+
def step_index(self):
|
| 106 |
+
"""
|
| 107 |
+
The index counter for current timestep. It will increase 1 after each scheduler step.
|
| 108 |
+
"""
|
| 109 |
+
return self._step_index
|
| 110 |
+
|
| 111 |
+
@property
|
| 112 |
+
def begin_index(self):
|
| 113 |
+
"""
|
| 114 |
+
The index for the first timestep. It should be set from pipeline with `set_begin_index` method.
|
| 115 |
+
"""
|
| 116 |
+
return self._begin_index
|
| 117 |
+
|
| 118 |
+
# Copied from diffusers.schedulers.scheduling_dpmsolver_multistep.DPMSolverMultistepScheduler.set_begin_index
|
| 119 |
+
def set_begin_index(self, begin_index: int = 0):
|
| 120 |
+
"""
|
| 121 |
+
Sets the begin index for the scheduler. This function should be run from pipeline before the inference.
|
| 122 |
+
|
| 123 |
+
Args:
|
| 124 |
+
begin_index (`int`):
|
| 125 |
+
The begin index for the scheduler.
|
| 126 |
+
"""
|
| 127 |
+
self._begin_index = begin_index
|
| 128 |
+
|
| 129 |
+
def scale_noise(
|
| 130 |
+
self,
|
| 131 |
+
sample: torch.FloatTensor,
|
| 132 |
+
timestep: Union[float, torch.FloatTensor],
|
| 133 |
+
noise: Optional[torch.FloatTensor] = None,
|
| 134 |
+
) -> torch.FloatTensor:
|
| 135 |
+
"""
|
| 136 |
+
Forward process in flow-matching
|
| 137 |
+
|
| 138 |
+
Args:
|
| 139 |
+
sample (`torch.FloatTensor`):
|
| 140 |
+
The input sample.
|
| 141 |
+
timestep (`int`, *optional*):
|
| 142 |
+
The current timestep in the diffusion chain.
|
| 143 |
+
|
| 144 |
+
Returns:
|
| 145 |
+
`torch.FloatTensor`:
|
| 146 |
+
A scaled input sample.
|
| 147 |
+
"""
|
| 148 |
+
# Make sure sigmas and timesteps have the same device and dtype as original_samples
|
| 149 |
+
sigmas = self.sigmas.to(device=sample.device, dtype=sample.dtype)
|
| 150 |
+
|
| 151 |
+
if sample.device.type == "mps" and torch.is_floating_point(timestep):
|
| 152 |
+
# mps does not support float64
|
| 153 |
+
schedule_timesteps = self.timesteps.to(sample.device, dtype=torch.float32)
|
| 154 |
+
timestep = timestep.to(sample.device, dtype=torch.float32)
|
| 155 |
+
else:
|
| 156 |
+
schedule_timesteps = self.timesteps.to(sample.device)
|
| 157 |
+
timestep = timestep.to(sample.device)
|
| 158 |
+
|
| 159 |
+
# self.begin_index is None when scheduler is used for training, or pipeline does not implement set_begin_index
|
| 160 |
+
if self.begin_index is None:
|
| 161 |
+
step_indices = [self.index_for_timestep(t, schedule_timesteps) for t in timestep]
|
| 162 |
+
elif self.step_index is not None:
|
| 163 |
+
# add_noise is called after first denoising step (for inpainting)
|
| 164 |
+
step_indices = [self.step_index] * timestep.shape[0]
|
| 165 |
+
else:
|
| 166 |
+
# add noise is called before first denoising step to create initial latent(img2img)
|
| 167 |
+
step_indices = [self.begin_index] * timestep.shape[0]
|
| 168 |
+
|
| 169 |
+
sigma = sigmas[step_indices].flatten()
|
| 170 |
+
while len(sigma.shape) < len(sample.shape):
|
| 171 |
+
sigma = sigma.unsqueeze(-1)
|
| 172 |
+
|
| 173 |
+
sample = sigma * noise + (1.0 - sigma) * sample
|
| 174 |
+
|
| 175 |
+
return sample
|
| 176 |
+
|
| 177 |
+
def _sigma_to_t(self, sigma):
|
| 178 |
+
return sigma * self.config.num_train_timesteps
|
| 179 |
+
|
| 180 |
+
def time_shift(self, mu: float, sigma: float, t: torch.Tensor):
|
| 181 |
+
return math.exp(mu) / (math.exp(mu) + (1 / t - 1) ** sigma)
|
| 182 |
+
|
| 183 |
+
def set_timesteps(
|
| 184 |
+
self,
|
| 185 |
+
num_inference_steps: int = None,
|
| 186 |
+
device: Union[str, torch.device] = None,
|
| 187 |
+
sigmas: Optional[List[float]] = None,
|
| 188 |
+
mu: Optional[float] = None,
|
| 189 |
+
):
|
| 190 |
+
"""
|
| 191 |
+
Sets the discrete timesteps used for the diffusion chain (to be run before inference).
|
| 192 |
+
|
| 193 |
+
Args:
|
| 194 |
+
num_inference_steps (`int`):
|
| 195 |
+
The number of diffusion steps used when generating samples with a pre-trained model.
|
| 196 |
+
device (`str` or `torch.device`, *optional*):
|
| 197 |
+
The device to which the timesteps should be moved to. If `None`, the timesteps are not moved.
|
| 198 |
+
"""
|
| 199 |
+
if self.config.use_dynamic_shifting and mu is None:
|
| 200 |
+
raise ValueError(" you have a pass a value for `mu` when `use_dynamic_shifting` is set to be `True`")
|
| 201 |
+
|
| 202 |
+
if sigmas is None:
|
| 203 |
+
timesteps = np.linspace(
|
| 204 |
+
self._sigma_to_t(self.sigma_max), self._sigma_to_t(self.sigma_min), num_inference_steps
|
| 205 |
+
)
|
| 206 |
+
|
| 207 |
+
sigmas = timesteps / self.config.num_train_timesteps
|
| 208 |
+
else:
|
| 209 |
+
sigmas = np.array(sigmas).astype(np.float32)
|
| 210 |
+
num_inference_steps = len(sigmas)
|
| 211 |
+
self.num_inference_steps = num_inference_steps
|
| 212 |
+
|
| 213 |
+
if self.config.use_dynamic_shifting:
|
| 214 |
+
sigmas = self.time_shift(mu, 1.0, sigmas)
|
| 215 |
+
else:
|
| 216 |
+
sigmas = self.config.shift * sigmas / (1 + (self.config.shift - 1) * sigmas)
|
| 217 |
+
|
| 218 |
+
if self.config.use_karras_sigmas:
|
| 219 |
+
sigmas = self._convert_to_karras(in_sigmas=sigmas, num_inference_steps=num_inference_steps)
|
| 220 |
+
|
| 221 |
+
elif self.config.use_exponential_sigmas:
|
| 222 |
+
sigmas = self._convert_to_exponential(in_sigmas=sigmas, num_inference_steps=num_inference_steps)
|
| 223 |
+
|
| 224 |
+
elif self.config.use_beta_sigmas:
|
| 225 |
+
sigmas = self._convert_to_beta(in_sigmas=sigmas, num_inference_steps=num_inference_steps)
|
| 226 |
+
|
| 227 |
+
sigmas = torch.from_numpy(sigmas).to(dtype=torch.float32, device=device)
|
| 228 |
+
timesteps = sigmas * self.config.num_train_timesteps
|
| 229 |
+
|
| 230 |
+
if self.config.invert_sigmas:
|
| 231 |
+
sigmas = 1.0 - sigmas
|
| 232 |
+
timesteps = sigmas * self.config.num_train_timesteps
|
| 233 |
+
sigmas = torch.cat([sigmas, torch.ones(1, device=sigmas.device)])
|
| 234 |
+
else:
|
| 235 |
+
sigmas = torch.cat([sigmas, torch.zeros(1, device=sigmas.device)])
|
| 236 |
+
|
| 237 |
+
self.timesteps = timesteps.to(device=device)
|
| 238 |
+
self.sigmas = sigmas
|
| 239 |
+
self._step_index = None
|
| 240 |
+
self._begin_index = None
|
| 241 |
+
|
| 242 |
+
def index_for_timestep(self, timestep, schedule_timesteps=None):
|
| 243 |
+
if schedule_timesteps is None:
|
| 244 |
+
schedule_timesteps = self.timesteps
|
| 245 |
+
|
| 246 |
+
indices = (schedule_timesteps == timestep).nonzero()
|
| 247 |
+
|
| 248 |
+
# The sigma index that is taken for the **very** first `step`
|
| 249 |
+
# is always the second index (or the last index if there is only 1)
|
| 250 |
+
# This way we can ensure we don't accidentally skip a sigma in
|
| 251 |
+
# case we start in the middle of the denoising schedule (e.g. for image-to-image)
|
| 252 |
+
pos = 1 if len(indices) > 1 else 0
|
| 253 |
+
|
| 254 |
+
return indices[pos].item()
|
| 255 |
+
|
| 256 |
+
def _init_step_index(self, timestep):
|
| 257 |
+
if self.begin_index is None:
|
| 258 |
+
if isinstance(timestep, torch.Tensor):
|
| 259 |
+
timestep = timestep.to(self.timesteps.device)
|
| 260 |
+
self._step_index = self.index_for_timestep(timestep)
|
| 261 |
+
else:
|
| 262 |
+
self._step_index = self._begin_index
|
| 263 |
+
|
| 264 |
+
def step(
|
| 265 |
+
self,
|
| 266 |
+
model_output: torch.FloatTensor,
|
| 267 |
+
timestep: Union[float, torch.FloatTensor],
|
| 268 |
+
sample: torch.FloatTensor,
|
| 269 |
+
s_churn: float = 0.0,
|
| 270 |
+
s_tmin: float = 0.0,
|
| 271 |
+
s_tmax: float = float("inf"),
|
| 272 |
+
s_noise: float = 1.0,
|
| 273 |
+
generator: Optional[torch.Generator] = None,
|
| 274 |
+
return_dict: bool = True,
|
| 275 |
+
) -> Union[FlashFlowMatchEulerDiscreteSchedulerOutput, Tuple]:
|
| 276 |
+
"""
|
| 277 |
+
Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
|
| 278 |
+
process from the learned model outputs (most often the predicted noise).
|
| 279 |
+
|
| 280 |
+
Args:
|
| 281 |
+
model_output (`torch.FloatTensor`):
|
| 282 |
+
The direct output from learned diffusion model.
|
| 283 |
+
timestep (`float`):
|
| 284 |
+
The current discrete timestep in the diffusion chain.
|
| 285 |
+
sample (`torch.FloatTensor`):
|
| 286 |
+
A current instance of a sample created by the diffusion process.
|
| 287 |
+
s_churn (`float`):
|
| 288 |
+
s_tmin (`float`):
|
| 289 |
+
s_tmax (`float`):
|
| 290 |
+
s_noise (`float`, defaults to 1.0):
|
| 291 |
+
Scaling factor for noise added to the sample.
|
| 292 |
+
generator (`torch.Generator`, *optional*):
|
| 293 |
+
A random number generator.
|
| 294 |
+
return_dict (`bool`):
|
| 295 |
+
Whether or not to return a [`~schedulers.scheduling_euler_discrete.EulerDiscreteSchedulerOutput`] or
|
| 296 |
+
tuple.
|
| 297 |
+
|
| 298 |
+
Returns:
|
| 299 |
+
[`~schedulers.scheduling_euler_discrete.EulerDiscreteSchedulerOutput`] or `tuple`:
|
| 300 |
+
If return_dict is `True`, [`~schedulers.scheduling_euler_discrete.EulerDiscreteSchedulerOutput`] is
|
| 301 |
+
returned, otherwise a tuple is returned where the first element is the sample tensor.
|
| 302 |
+
"""
|
| 303 |
+
|
| 304 |
+
if (
|
| 305 |
+
isinstance(timestep, int)
|
| 306 |
+
or isinstance(timestep, torch.IntTensor)
|
| 307 |
+
or isinstance(timestep, torch.LongTensor)
|
| 308 |
+
):
|
| 309 |
+
raise ValueError(
|
| 310 |
+
(
|
| 311 |
+
"Passing integer indices (e.g. from `enumerate(timesteps)`) as timesteps to"
|
| 312 |
+
" `EulerDiscreteScheduler.step()` is not supported. Make sure to pass"
|
| 313 |
+
" one of the `scheduler.timesteps` as a timestep."
|
| 314 |
+
),
|
| 315 |
+
)
|
| 316 |
+
|
| 317 |
+
if self.step_index is None:
|
| 318 |
+
self._init_step_index(timestep)
|
| 319 |
+
|
| 320 |
+
# Upcast to avoid precision issues when computing prev_sample
|
| 321 |
+
|
| 322 |
+
sigma = self.sigmas[self.step_index]
|
| 323 |
+
|
| 324 |
+
# Upcast to avoid precision issues when computing prev_sample
|
| 325 |
+
sample = sample.to(torch.float32)
|
| 326 |
+
|
| 327 |
+
denoised = sample - model_output * sigma
|
| 328 |
+
|
| 329 |
+
if self.step_index < self.num_inference_steps - 1:
|
| 330 |
+
sigma_next = self.sigmas[self.step_index + 1]
|
| 331 |
+
noise = randn_tensor(
|
| 332 |
+
model_output.shape,
|
| 333 |
+
generator=generator,
|
| 334 |
+
device=model_output.device,
|
| 335 |
+
dtype=denoised.dtype,
|
| 336 |
+
)
|
| 337 |
+
sample = sigma_next * noise + (1.0 - sigma_next) * denoised
|
| 338 |
+
|
| 339 |
+
self._step_index += 1
|
| 340 |
+
sample = sample.to(model_output.dtype)
|
| 341 |
+
|
| 342 |
+
if not return_dict:
|
| 343 |
+
return (sample,)
|
| 344 |
+
|
| 345 |
+
return FlashFlowMatchEulerDiscreteSchedulerOutput(prev_sample=sample)
|
| 346 |
+
|
| 347 |
+
# Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler._convert_to_karras
|
| 348 |
+
def _convert_to_karras(self, in_sigmas: torch.Tensor, num_inference_steps) -> torch.Tensor:
|
| 349 |
+
"""Constructs the noise schedule of Karras et al. (2022)."""
|
| 350 |
+
|
| 351 |
+
# Hack to make sure that other schedulers which copy this function don't break
|
| 352 |
+
# TODO: Add this logic to the other schedulers
|
| 353 |
+
if hasattr(self.config, "sigma_min"):
|
| 354 |
+
sigma_min = self.config.sigma_min
|
| 355 |
+
else:
|
| 356 |
+
sigma_min = None
|
| 357 |
+
|
| 358 |
+
if hasattr(self.config, "sigma_max"):
|
| 359 |
+
sigma_max = self.config.sigma_max
|
| 360 |
+
else:
|
| 361 |
+
sigma_max = None
|
| 362 |
+
|
| 363 |
+
sigma_min = sigma_min if sigma_min is not None else in_sigmas[-1].item()
|
| 364 |
+
sigma_max = sigma_max if sigma_max is not None else in_sigmas[0].item()
|
| 365 |
+
|
| 366 |
+
rho = 7.0 # 7.0 is the value used in the paper
|
| 367 |
+
ramp = np.linspace(0, 1, num_inference_steps)
|
| 368 |
+
min_inv_rho = sigma_min ** (1 / rho)
|
| 369 |
+
max_inv_rho = sigma_max ** (1 / rho)
|
| 370 |
+
sigmas = (max_inv_rho + ramp * (min_inv_rho - max_inv_rho)) ** rho
|
| 371 |
+
return sigmas
|
| 372 |
+
|
| 373 |
+
# Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler._convert_to_exponential
|
| 374 |
+
def _convert_to_exponential(self, in_sigmas: torch.Tensor, num_inference_steps: int) -> torch.Tensor:
|
| 375 |
+
"""Constructs an exponential noise schedule."""
|
| 376 |
+
|
| 377 |
+
# Hack to make sure that other schedulers which copy this function don't break
|
| 378 |
+
# TODO: Add this logic to the other schedulers
|
| 379 |
+
if hasattr(self.config, "sigma_min"):
|
| 380 |
+
sigma_min = self.config.sigma_min
|
| 381 |
+
else:
|
| 382 |
+
sigma_min = None
|
| 383 |
+
|
| 384 |
+
if hasattr(self.config, "sigma_max"):
|
| 385 |
+
sigma_max = self.config.sigma_max
|
| 386 |
+
else:
|
| 387 |
+
sigma_max = None
|
| 388 |
+
|
| 389 |
+
sigma_min = sigma_min if sigma_min is not None else in_sigmas[-1].item()
|
| 390 |
+
sigma_max = sigma_max if sigma_max is not None else in_sigmas[0].item()
|
| 391 |
+
|
| 392 |
+
sigmas = np.exp(np.linspace(math.log(sigma_max), math.log(sigma_min), num_inference_steps))
|
| 393 |
+
return sigmas
|
| 394 |
+
|
| 395 |
+
# Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler._convert_to_beta
|
| 396 |
+
def _convert_to_beta(
|
| 397 |
+
self, in_sigmas: torch.Tensor, num_inference_steps: int, alpha: float = 0.6, beta: float = 0.6
|
| 398 |
+
) -> torch.Tensor:
|
| 399 |
+
"""From "Beta Sampling is All You Need" [arXiv:2407.12173] (Lee et. al, 2024)"""
|
| 400 |
+
|
| 401 |
+
# Hack to make sure that other schedulers which copy this function don't break
|
| 402 |
+
# TODO: Add this logic to the other schedulers
|
| 403 |
+
if hasattr(self.config, "sigma_min"):
|
| 404 |
+
sigma_min = self.config.sigma_min
|
| 405 |
+
else:
|
| 406 |
+
sigma_min = None
|
| 407 |
+
|
| 408 |
+
if hasattr(self.config, "sigma_max"):
|
| 409 |
+
sigma_max = self.config.sigma_max
|
| 410 |
+
else:
|
| 411 |
+
sigma_max = None
|
| 412 |
+
|
| 413 |
+
sigma_min = sigma_min if sigma_min is not None else in_sigmas[-1].item()
|
| 414 |
+
sigma_max = sigma_max if sigma_max is not None else in_sigmas[0].item()
|
| 415 |
+
|
| 416 |
+
sigmas = np.array(
|
| 417 |
+
[
|
| 418 |
+
sigma_min + (ppf * (sigma_max - sigma_min))
|
| 419 |
+
for ppf in [
|
| 420 |
+
scipy.stats.beta.ppf(timestep, alpha, beta)
|
| 421 |
+
for timestep in 1 - np.linspace(0, 1, num_inference_steps)
|
| 422 |
+
]
|
| 423 |
+
]
|
| 424 |
+
)
|
| 425 |
+
return sigmas
|
| 426 |
+
|
| 427 |
+
def __len__(self):
|
| 428 |
+
return self.config.num_train_timesteps
|