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| author | Volpeon <git@volpeon.ink> | 2023-03-01 12:34:42 +0100 |
|---|---|---|
| committer | Volpeon <git@volpeon.ink> | 2023-03-01 12:34:42 +0100 |
| commit | a1b8327085ddeab589be074d7e9df4291aba1210 (patch) | |
| tree | 2f2016916d7a2f659268c3e375d55c59583c2b3b /schedulers | |
| parent | Fixed TI normalization order (diff) | |
| download | textual-inversion-diff-a1b8327085ddeab589be074d7e9df4291aba1210.tar.gz textual-inversion-diff-a1b8327085ddeab589be074d7e9df4291aba1210.tar.bz2 textual-inversion-diff-a1b8327085ddeab589be074d7e9df4291aba1210.zip | |
Update
Diffstat (limited to 'schedulers')
| -rw-r--r-- | schedulers/scheduling_deis_multistep.py | 500 |
1 files changed, 0 insertions, 500 deletions
diff --git a/schedulers/scheduling_deis_multistep.py b/schedulers/scheduling_deis_multistep.py deleted file mode 100644 index ea1281e..0000000 --- a/schedulers/scheduling_deis_multistep.py +++ /dev/null | |||
| @@ -1,500 +0,0 @@ | |||
| 1 | # Copyright 2022 FLAIR Lab 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 | # DISCLAIMER: check https://arxiv.org/abs/2204.13902 and https://github.com/qsh-zh/deis for more info | ||
| 16 | # The codebase is modified based on https://github.com/huggingface/diffusers/blob/main/src/diffusers/schedulers/scheduling_dpmsolver_multistep.py | ||
| 17 | |||
| 18 | import math | ||
| 19 | from typing import List, Optional, Tuple, Union | ||
| 20 | |||
| 21 | import numpy as np | ||
| 22 | import torch | ||
| 23 | |||
| 24 | from diffusers.configuration_utils import ConfigMixin, register_to_config | ||
| 25 | from diffusers.schedulers.scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin, SchedulerOutput | ||
| 26 | |||
| 27 | |||
| 28 | def betas_for_alpha_bar(num_diffusion_timesteps, max_beta=0.999): | ||
| 29 | """ | ||
| 30 | Create a beta schedule that discretizes the given alpha_t_bar function, which defines the cumulative product of | ||
| 31 | (1-beta) over time from t = [0,1]. | ||
| 32 | |||
| 33 | Contains a function alpha_bar that takes an argument t and transforms it to the cumulative product of (1-beta) up | ||
| 34 | to that part of the diffusion process. | ||
| 35 | |||
| 36 | |||
| 37 | Args: | ||
| 38 | num_diffusion_timesteps (`int`): the number of betas to produce. | ||
| 39 | max_beta (`float`): the maximum beta to use; use values lower than 1 to | ||
| 40 | prevent singularities. | ||
| 41 | |||
| 42 | Returns: | ||
| 43 | betas (`np.ndarray`): the betas used by the scheduler to step the model outputs | ||
| 44 | """ | ||
| 45 | |||
| 46 | def alpha_bar(time_step): | ||
| 47 | return math.cos((time_step + 0.008) / 1.008 * math.pi / 2) ** 2 | ||
| 48 | |||
| 49 | betas = [] | ||
| 50 | for i in range(num_diffusion_timesteps): | ||
| 51 | t1 = i / num_diffusion_timesteps | ||
| 52 | t2 = (i + 1) / num_diffusion_timesteps | ||
| 53 | betas.append(min(1 - alpha_bar(t2) / alpha_bar(t1), max_beta)) | ||
| 54 | return torch.tensor(betas, dtype=torch.float32) | ||
| 55 | |||
| 56 | |||
| 57 | class DEISMultistepScheduler(SchedulerMixin, ConfigMixin): | ||
| 58 | """ | ||
| 59 | DEIS (https://arxiv.org/abs/2204.13902) is a fast high order solver for diffusion ODEs. We slightly modify the | ||
| 60 | polynomial fitting formula in log-rho space instead of the original linear t space in DEIS paper. The modification | ||
| 61 | enjoys closed-form coefficients for exponential multistep update instead of replying on the numerical solver. More | ||
| 62 | variants of DEIS can be found in https://github.com/qsh-zh/deis. | ||
| 63 | |||
| 64 | Currently, we support the log-rho multistep DEIS. We recommend to use `solver_order=2 / 3` while `solver_order=1` | ||
| 65 | reduces to DDIM. | ||
| 66 | |||
| 67 | We also support the "dynamic thresholding" method in Imagen (https://arxiv.org/abs/2205.11487). For pixel-space | ||
| 68 | diffusion models, you can set `thresholding=True` to use the dynamic thresholding. | ||
| 69 | |||
| 70 | [`~ConfigMixin`] takes care of storing all config attributes that are passed in the scheduler's `__init__` | ||
| 71 | function, such as `num_train_timesteps`. They can be accessed via `scheduler.config.num_train_timesteps`. | ||
| 72 | [`SchedulerMixin`] provides general loading and saving functionality via the [`SchedulerMixin.save_pretrained`] and | ||
| 73 | [`~SchedulerMixin.from_pretrained`] functions. | ||
| 74 | |||
| 75 | Args: | ||
| 76 | num_train_timesteps (`int`): number of diffusion steps used to train the model. | ||
| 77 | beta_start (`float`): the starting `beta` value of inference. | ||
| 78 | beta_end (`float`): the final `beta` value. | ||
| 79 | beta_schedule (`str`): | ||
| 80 | the beta schedule, a mapping from a beta range to a sequence of betas for stepping the model. Choose from | ||
| 81 | `linear`, `scaled_linear`, or `squaredcos_cap_v2`. | ||
| 82 | trained_betas (`np.ndarray`, optional): | ||
| 83 | option to pass an array of betas directly to the constructor to bypass `beta_start`, `beta_end` etc. | ||
| 84 | solver_order (`int`, default `2`): | ||
| 85 | the order of DEIS; can be `1` or `2` or `3`. We recommend to use `solver_order=2` for guided sampling, and | ||
| 86 | `solver_order=3` for unconditional sampling. | ||
| 87 | prediction_type (`str`, default `epsilon`): | ||
| 88 | indicates whether the model predicts the noise (epsilon), or the data / `x0`. One of `epsilon`, `sample`, | ||
| 89 | or `v-prediction`. | ||
| 90 | thresholding (`bool`, default `False`): | ||
| 91 | whether to use the "dynamic thresholding" method (introduced by Imagen, https://arxiv.org/abs/2205.11487). | ||
| 92 | Note that the thresholding method is unsuitable for latent-space diffusion models (such as | ||
| 93 | stable-diffusion). | ||
| 94 | dynamic_thresholding_ratio (`float`, default `0.995`): | ||
| 95 | the ratio for the dynamic thresholding method. Default is `0.995`, the same as Imagen | ||
| 96 | (https://arxiv.org/abs/2205.11487). | ||
| 97 | sample_max_value (`float`, default `1.0`): | ||
| 98 | the threshold value for dynamic thresholding. Valid woks when `thresholding=True` | ||
| 99 | algorithm_type (`str`, default `deis`): | ||
| 100 | the algorithm type for the solver. current we support multistep deis, we will add other variants of DEIS in | ||
| 101 | the future | ||
| 102 | lower_order_final (`bool`, default `True`): | ||
| 103 | whether to use lower-order solvers in the final steps. Only valid for < 15 inference steps. We empirically | ||
| 104 | find this trick can stabilize the sampling of DEIS for steps < 15, especially for steps <= 10. | ||
| 105 | |||
| 106 | """ | ||
| 107 | |||
| 108 | _compatibles = [e.name for e in KarrasDiffusionSchedulers] | ||
| 109 | order = 1 | ||
| 110 | |||
| 111 | @register_to_config | ||
| 112 | def __init__( | ||
| 113 | self, | ||
| 114 | num_train_timesteps: int = 1000, | ||
| 115 | beta_start: float = 0.0001, | ||
| 116 | beta_end: float = 0.02, | ||
| 117 | beta_schedule: str = "linear", | ||
| 118 | trained_betas: Optional[np.ndarray] = None, | ||
| 119 | solver_order: int = 2, | ||
| 120 | prediction_type: str = "epsilon", | ||
| 121 | thresholding: bool = False, | ||
| 122 | dynamic_thresholding_ratio: float = 0.995, | ||
| 123 | sample_max_value: float = 1.0, | ||
| 124 | algorithm_type: str = "deis", | ||
| 125 | solver_type: str = "logrho", | ||
| 126 | lower_order_final: bool = True, | ||
| 127 | ): | ||
| 128 | if trained_betas is not None: | ||
| 129 | self.betas = torch.tensor(trained_betas, dtype=torch.float32) | ||
| 130 | elif beta_schedule == "linear": | ||
| 131 | self.betas = torch.linspace(beta_start, beta_end, num_train_timesteps, dtype=torch.float32) | ||
| 132 | elif beta_schedule == "scaled_linear": | ||
| 133 | # this schedule is very specific to the latent diffusion model. | ||
| 134 | self.betas = ( | ||
| 135 | torch.linspace(beta_start**0.5, beta_end**0.5, num_train_timesteps, dtype=torch.float32) ** 2 | ||
| 136 | ) | ||
| 137 | elif beta_schedule == "squaredcos_cap_v2": | ||
| 138 | # Glide cosine schedule | ||
| 139 | self.betas = betas_for_alpha_bar(num_train_timesteps) | ||
| 140 | else: | ||
| 141 | raise NotImplementedError(f"{beta_schedule} does is not implemented for {self.__class__}") | ||
| 142 | |||
| 143 | self.alphas = 1.0 - self.betas | ||
| 144 | self.alphas_cumprod = torch.cumprod(self.alphas, dim=0) | ||
| 145 | # Currently we only support VP-type noise schedule | ||
| 146 | self.alpha_t = torch.sqrt(self.alphas_cumprod) | ||
| 147 | self.sigma_t = torch.sqrt(1 - self.alphas_cumprod) | ||
| 148 | self.lambda_t = torch.log(self.alpha_t) - torch.log(self.sigma_t) | ||
| 149 | |||
| 150 | # standard deviation of the initial noise distribution | ||
| 151 | self.init_noise_sigma = 1.0 | ||
| 152 | |||
| 153 | # settings for DEIS | ||
| 154 | if algorithm_type not in ["deis"]: | ||
| 155 | if algorithm_type in ["dpmsolver", "dpmsolver++"]: | ||
| 156 | algorithm_type = "deis" | ||
| 157 | else: | ||
| 158 | raise NotImplementedError(f"{algorithm_type} does is not implemented for {self.__class__}") | ||
| 159 | |||
| 160 | if solver_type not in ["logrho"]: | ||
| 161 | if solver_type in ["midpoint", "heun"]: | ||
| 162 | solver_type = "logrho" | ||
| 163 | else: | ||
| 164 | raise NotImplementedError(f"solver type {solver_type} does is not implemented for {self.__class__}") | ||
| 165 | |||
| 166 | # setable values | ||
| 167 | self.num_inference_steps = None | ||
| 168 | timesteps = np.linspace(0, num_train_timesteps - 1, num_train_timesteps, dtype=np.float32)[::-1].copy() | ||
| 169 | self.timesteps = torch.from_numpy(timesteps) | ||
| 170 | self.model_outputs = [None] * solver_order | ||
| 171 | self.lower_order_nums = 0 | ||
| 172 | |||
| 173 | def set_timesteps(self, num_inference_steps: int, device: Union[str, torch.device] = None): | ||
| 174 | """ | ||
| 175 | Sets the timesteps used for the diffusion chain. Supporting function to be run before inference. | ||
| 176 | |||
| 177 | Args: | ||
| 178 | num_inference_steps (`int`): | ||
| 179 | the number of diffusion steps used when generating samples with a pre-trained model. | ||
| 180 | device (`str` or `torch.device`, optional): | ||
| 181 | the device to which the timesteps should be moved to. If `None`, the timesteps are not moved. | ||
| 182 | """ | ||
| 183 | self.num_inference_steps = num_inference_steps | ||
| 184 | timesteps = ( | ||
| 185 | np.linspace(0, self.num_train_timesteps - 1, num_inference_steps + 1) | ||
| 186 | .round()[::-1][:-1] | ||
| 187 | .copy() | ||
| 188 | .astype(np.int64) | ||
| 189 | ) | ||
| 190 | self.timesteps = torch.from_numpy(timesteps).to(device) | ||
| 191 | self.model_outputs = [ | ||
| 192 | None, | ||
| 193 | ] * self.config.solver_order | ||
| 194 | self.lower_order_nums = 0 | ||
| 195 | |||
| 196 | def convert_model_output( | ||
| 197 | self, model_output: torch.FloatTensor, timestep: int, sample: torch.FloatTensor | ||
| 198 | ) -> torch.FloatTensor: | ||
| 199 | """ | ||
| 200 | Convert the model output to the corresponding type that the algorithm DEIS needs. | ||
| 201 | |||
| 202 | Args: | ||
| 203 | model_output (`torch.FloatTensor`): direct output from learned diffusion model. | ||
| 204 | timestep (`int`): current discrete timestep in the diffusion chain. | ||
| 205 | sample (`torch.FloatTensor`): | ||
| 206 | current instance of sample being created by diffusion process. | ||
| 207 | |||
| 208 | Returns: | ||
| 209 | `torch.FloatTensor`: the converted model output. | ||
| 210 | """ | ||
| 211 | if self.config.prediction_type == "epsilon": | ||
| 212 | alpha_t, sigma_t = self.alpha_t[timestep], self.sigma_t[timestep] | ||
| 213 | x0_pred = (sample - sigma_t * model_output) / alpha_t | ||
| 214 | elif self.config.prediction_type == "sample": | ||
| 215 | x0_pred = model_output | ||
| 216 | elif self.config.prediction_type == "v_prediction": | ||
| 217 | alpha_t, sigma_t = self.alpha_t[timestep], self.sigma_t[timestep] | ||
| 218 | x0_pred = alpha_t * sample - sigma_t * model_output | ||
| 219 | else: | ||
| 220 | raise ValueError( | ||
| 221 | f"prediction_type given as {self.config.prediction_type} must be one of `epsilon`, `sample`, or" | ||
| 222 | " `v_prediction` for the DEISMultistepScheduler." | ||
| 223 | ) | ||
| 224 | |||
| 225 | if self.config.thresholding: | ||
| 226 | # Dynamic thresholding in https://arxiv.org/abs/2205.11487 | ||
| 227 | orig_dtype = x0_pred.dtype | ||
| 228 | if orig_dtype not in [torch.float, torch.double]: | ||
| 229 | x0_pred = x0_pred.float() | ||
| 230 | dynamic_max_val = torch.quantile( | ||
| 231 | torch.abs(x0_pred).reshape((x0_pred.shape[0], -1)), self.config.dynamic_thresholding_ratio, dim=1 | ||
| 232 | ) | ||
| 233 | dynamic_max_val = torch.maximum( | ||
| 234 | dynamic_max_val, | ||
| 235 | self.config.sample_max_value * torch.ones_like(dynamic_max_val).to(dynamic_max_val.device), | ||
| 236 | )[(...,) + (None,) * (x0_pred.ndim - 1)] | ||
| 237 | x0_pred = torch.clamp(x0_pred, -dynamic_max_val, dynamic_max_val) / dynamic_max_val | ||
| 238 | x0_pred = x0_pred.type(orig_dtype) | ||
| 239 | |||
| 240 | if self.config.algorithm_type == "deis": | ||
| 241 | alpha_t, sigma_t = self.alpha_t[timestep], self.sigma_t[timestep] | ||
| 242 | return (sample - alpha_t * x0_pred) / sigma_t | ||
| 243 | else: | ||
| 244 | raise NotImplementedError("only support log-rho multistep deis now") | ||
| 245 | |||
| 246 | def deis_first_order_update( | ||
| 247 | self, | ||
| 248 | model_output: torch.FloatTensor, | ||
| 249 | timestep: int, | ||
| 250 | prev_timestep: int, | ||
| 251 | sample: torch.FloatTensor, | ||
| 252 | ) -> torch.FloatTensor: | ||
| 253 | """ | ||
| 254 | One step for the first-order DEIS (equivalent to DDIM). | ||
| 255 | |||
| 256 | Args: | ||
| 257 | model_output (`torch.FloatTensor`): direct output from learned diffusion model. | ||
| 258 | timestep (`int`): current discrete timestep in the diffusion chain. | ||
| 259 | prev_timestep (`int`): previous discrete timestep in the diffusion chain. | ||
| 260 | sample (`torch.FloatTensor`): | ||
| 261 | current instance of sample being created by diffusion process. | ||
| 262 | |||
| 263 | Returns: | ||
| 264 | `torch.FloatTensor`: the sample tensor at the previous timestep. | ||
| 265 | """ | ||
| 266 | lambda_t, lambda_s = self.lambda_t[prev_timestep], self.lambda_t[timestep] | ||
| 267 | alpha_t, alpha_s = self.alpha_t[prev_timestep], self.alpha_t[timestep] | ||
| 268 | sigma_t, _ = self.sigma_t[prev_timestep], self.sigma_t[timestep] | ||
| 269 | h = lambda_t - lambda_s | ||
| 270 | if self.config.algorithm_type == "deis": | ||
| 271 | x_t = (alpha_t / alpha_s) * sample - (sigma_t * (torch.exp(h) - 1.0)) * model_output | ||
| 272 | else: | ||
| 273 | raise NotImplementedError("only support log-rho multistep deis now") | ||
| 274 | return x_t | ||
| 275 | |||
| 276 | def multistep_deis_second_order_update( | ||
| 277 | self, | ||
| 278 | model_output_list: List[torch.FloatTensor], | ||
| 279 | timestep_list: List[int], | ||
| 280 | prev_timestep: int, | ||
| 281 | sample: torch.FloatTensor, | ||
| 282 | ) -> torch.FloatTensor: | ||
| 283 | """ | ||
| 284 | One step for the second-order multistep DEIS. | ||
| 285 | |||
| 286 | Args: | ||
| 287 | model_output_list (`List[torch.FloatTensor]`): | ||
| 288 | direct outputs from learned diffusion model at current and latter timesteps. | ||
| 289 | timestep (`int`): current and latter discrete timestep in the diffusion chain. | ||
| 290 | prev_timestep (`int`): previous discrete timestep in the diffusion chain. | ||
| 291 | sample (`torch.FloatTensor`): | ||
| 292 | current instance of sample being created by diffusion process. | ||
| 293 | |||
| 294 | Returns: | ||
| 295 | `torch.FloatTensor`: the sample tensor at the previous timestep. | ||
| 296 | """ | ||
| 297 | t, s0, s1 = prev_timestep, timestep_list[-1], timestep_list[-2] | ||
| 298 | m0, m1 = model_output_list[-1], model_output_list[-2] | ||
| 299 | alpha_t, alpha_s0, alpha_s1 = self.alpha_t[t], self.alpha_t[s0], self.alpha_t[s1] | ||
| 300 | sigma_t, sigma_s0, sigma_s1 = self.sigma_t[t], self.sigma_t[s0], self.sigma_t[s1] | ||
| 301 | |||
| 302 | rho_t, rho_s0, rho_s1 = sigma_t / alpha_t, sigma_s0 / alpha_s0, sigma_s1 / alpha_s1 | ||
| 303 | |||
| 304 | if self.config.algorithm_type == "deis": | ||
| 305 | |||
| 306 | def ind_fn(t, b, c): | ||
| 307 | # Integrate[(log(t) - log(c)) / (log(b) - log(c)), {t}] | ||
| 308 | return t * (-np.log(c) + np.log(t) - 1) / (np.log(b) - np.log(c)) | ||
| 309 | |||
| 310 | coef1 = ind_fn(rho_t, rho_s0, rho_s1) - ind_fn(rho_s0, rho_s0, rho_s1) | ||
| 311 | coef2 = ind_fn(rho_t, rho_s1, rho_s0) - ind_fn(rho_s0, rho_s1, rho_s0) | ||
| 312 | |||
| 313 | x_t = alpha_t * (sample / alpha_s0 + coef1 * m0 + coef2 * m1) | ||
| 314 | return x_t | ||
| 315 | else: | ||
| 316 | raise NotImplementedError("only support log-rho multistep deis now") | ||
| 317 | |||
| 318 | def multistep_deis_third_order_update( | ||
| 319 | self, | ||
| 320 | model_output_list: List[torch.FloatTensor], | ||
| 321 | timestep_list: List[int], | ||
| 322 | prev_timestep: int, | ||
| 323 | sample: torch.FloatTensor, | ||
| 324 | ) -> torch.FloatTensor: | ||
| 325 | """ | ||
| 326 | One step for the third-order multistep DEIS. | ||
| 327 | |||
| 328 | Args: | ||
| 329 | model_output_list (`List[torch.FloatTensor]`): | ||
| 330 | direct outputs from learned diffusion model at current and latter timesteps. | ||
| 331 | timestep (`int`): current and latter discrete timestep in the diffusion chain. | ||
| 332 | prev_timestep (`int`): previous discrete timestep in the diffusion chain. | ||
| 333 | sample (`torch.FloatTensor`): | ||
| 334 | current instance of sample being created by diffusion process. | ||
| 335 | |||
| 336 | Returns: | ||
| 337 | `torch.FloatTensor`: the sample tensor at the previous timestep. | ||
| 338 | """ | ||
| 339 | t, s0, s1, s2 = prev_timestep, timestep_list[-1], timestep_list[-2], timestep_list[-3] | ||
| 340 | m0, m1, m2 = model_output_list[-1], model_output_list[-2], model_output_list[-3] | ||
| 341 | alpha_t, alpha_s0, alpha_s1, alpha_s2 = self.alpha_t[t], self.alpha_t[s0], self.alpha_t[s1], self.alpha_t[s2] | ||
| 342 | sigma_t, sigma_s0, sigma_s1, simga_s2 = self.sigma_t[t], self.sigma_t[s0], self.sigma_t[s1], self.sigma_t[s2] | ||
| 343 | rho_t, rho_s0, rho_s1, rho_s2 = ( | ||
| 344 | sigma_t / alpha_t, | ||
| 345 | sigma_s0 / alpha_s0, | ||
| 346 | sigma_s1 / alpha_s1, | ||
| 347 | simga_s2 / alpha_s2, | ||
| 348 | ) | ||
| 349 | |||
| 350 | if self.config.algorithm_type == "deis": | ||
| 351 | |||
| 352 | def ind_fn(t, b, c, d): | ||
| 353 | # Integrate[(log(t) - log(c))(log(t) - log(d)) / (log(b) - log(c))(log(b) - log(d)), {t}] | ||
| 354 | numerator = t * ( | ||
| 355 | np.log(c) * (np.log(d) - np.log(t) + 1) | ||
| 356 | - np.log(d) * np.log(t) | ||
| 357 | + np.log(d) | ||
| 358 | + np.log(t) ** 2 | ||
| 359 | - 2 * np.log(t) | ||
| 360 | + 2 | ||
| 361 | ) | ||
| 362 | denominator = (np.log(b) - np.log(c)) * (np.log(b) - np.log(d)) | ||
| 363 | return numerator / denominator | ||
| 364 | |||
| 365 | coef1 = ind_fn(rho_t, rho_s0, rho_s1, rho_s2) - ind_fn(rho_s0, rho_s0, rho_s1, rho_s2) | ||
| 366 | coef2 = ind_fn(rho_t, rho_s1, rho_s2, rho_s0) - ind_fn(rho_s0, rho_s1, rho_s2, rho_s0) | ||
| 367 | coef3 = ind_fn(rho_t, rho_s2, rho_s0, rho_s1) - ind_fn(rho_s0, rho_s2, rho_s0, rho_s1) | ||
| 368 | |||
| 369 | x_t = alpha_t * (sample / alpha_s0 + coef1 * m0 + coef2 * m1 + coef3 * m2) | ||
| 370 | |||
| 371 | return x_t | ||
| 372 | else: | ||
| 373 | raise NotImplementedError("only support log-rho multistep deis now") | ||
| 374 | |||
| 375 | def step( | ||
| 376 | self, | ||
| 377 | model_output: torch.FloatTensor, | ||
| 378 | timestep: int, | ||
| 379 | sample: torch.FloatTensor, | ||
| 380 | return_dict: bool = True, | ||
| 381 | ) -> Union[SchedulerOutput, Tuple]: | ||
| 382 | """ | ||
| 383 | Step function propagating the sample with the multistep DEIS. | ||
| 384 | |||
| 385 | Args: | ||
| 386 | model_output (`torch.FloatTensor`): direct output from learned diffusion model. | ||
| 387 | timestep (`int`): current discrete timestep in the diffusion chain. | ||
| 388 | sample (`torch.FloatTensor`): | ||
| 389 | current instance of sample being created by diffusion process. | ||
| 390 | return_dict (`bool`): option for returning tuple rather than SchedulerOutput class | ||
| 391 | |||
| 392 | Returns: | ||
| 393 | [`~scheduling_utils.SchedulerOutput`] or `tuple`: [`~scheduling_utils.SchedulerOutput`] if `return_dict` is | ||
| 394 | True, otherwise a `tuple`. When returning a tuple, the first element is the sample tensor. | ||
| 395 | |||
| 396 | """ | ||
| 397 | if self.num_inference_steps is None: | ||
| 398 | raise ValueError( | ||
| 399 | "Number of inference steps is 'None', you need to run 'set_timesteps' after creating the scheduler" | ||
| 400 | ) | ||
| 401 | |||
| 402 | if isinstance(timestep, torch.Tensor): | ||
| 403 | timestep = timestep.to(self.timesteps.device) | ||
| 404 | step_index = (self.timesteps == timestep).nonzero() | ||
| 405 | if len(step_index) == 0: | ||
| 406 | step_index = len(self.timesteps) - 1 | ||
| 407 | else: | ||
| 408 | step_index = step_index.item() | ||
| 409 | prev_timestep = 0 if step_index == len(self.timesteps) - 1 else self.timesteps[step_index + 1] | ||
| 410 | lower_order_final = ( | ||
| 411 | (step_index == len(self.timesteps) - 1) and self.config.lower_order_final and len(self.timesteps) < 15 | ||
| 412 | ) | ||
| 413 | lower_order_second = ( | ||
| 414 | (step_index == len(self.timesteps) - 2) and self.config.lower_order_final and len(self.timesteps) < 15 | ||
| 415 | ) | ||
| 416 | |||
| 417 | model_output = self.convert_model_output(model_output, timestep, sample) | ||
| 418 | for i in range(self.config.solver_order - 1): | ||
| 419 | self.model_outputs[i] = self.model_outputs[i + 1] | ||
| 420 | self.model_outputs[-1] = model_output | ||
| 421 | |||
| 422 | if self.config.solver_order == 1 or self.lower_order_nums < 1 or lower_order_final: | ||
| 423 | prev_sample = self.deis_first_order_update(model_output, timestep, prev_timestep, sample) | ||
| 424 | elif self.config.solver_order == 2 or self.lower_order_nums < 2 or lower_order_second: | ||
| 425 | timestep_list = [self.timesteps[step_index - 1], timestep] | ||
| 426 | prev_sample = self.multistep_deis_second_order_update( | ||
| 427 | self.model_outputs, timestep_list, prev_timestep, sample | ||
| 428 | ) | ||
| 429 | else: | ||
| 430 | timestep_list = [self.timesteps[step_index - 2], self.timesteps[step_index - 1], timestep] | ||
| 431 | prev_sample = self.multistep_deis_third_order_update( | ||
| 432 | self.model_outputs, timestep_list, prev_timestep, sample | ||
| 433 | ) | ||
| 434 | |||
| 435 | if self.lower_order_nums < self.config.solver_order: | ||
| 436 | self.lower_order_nums += 1 | ||
| 437 | |||
| 438 | if not return_dict: | ||
| 439 | return (prev_sample,) | ||
| 440 | |||
| 441 | return SchedulerOutput(prev_sample=prev_sample) | ||
| 442 | |||
| 443 | def scale_model_input(self, sample: torch.FloatTensor, *args, **kwargs) -> torch.FloatTensor: | ||
| 444 | """ | ||
| 445 | Ensures interchangeability with schedulers that need to scale the denoising model input depending on the | ||
| 446 | current timestep. | ||
| 447 | |||
| 448 | Args: | ||
| 449 | sample (`torch.FloatTensor`): input sample | ||
| 450 | |||
| 451 | Returns: | ||
| 452 | `torch.FloatTensor`: scaled input sample | ||
| 453 | """ | ||
| 454 | return sample | ||
| 455 | |||
| 456 | def add_noise( | ||
| 457 | self, | ||
| 458 | original_samples: torch.FloatTensor, | ||
| 459 | noise: torch.FloatTensor, | ||
| 460 | timesteps: torch.IntTensor, | ||
| 461 | ) -> torch.FloatTensor: | ||
| 462 | # Make sure alphas_cumprod and timestep have same device and dtype as original_samples | ||
| 463 | self.alphas_cumprod = self.alphas_cumprod.to(device=original_samples.device, dtype=original_samples.dtype) | ||
| 464 | timesteps = timesteps.to(original_samples.device) | ||
| 465 | |||
| 466 | sqrt_alpha_prod = self.alphas_cumprod[timesteps] ** 0.5 | ||
| 467 | sqrt_alpha_prod = sqrt_alpha_prod.flatten() | ||
| 468 | while len(sqrt_alpha_prod.shape) < len(original_samples.shape): | ||
| 469 | sqrt_alpha_prod = sqrt_alpha_prod.unsqueeze(-1) | ||
| 470 | |||
| 471 | sqrt_one_minus_alpha_prod = (1 - self.alphas_cumprod[timesteps]) ** 0.5 | ||
| 472 | sqrt_one_minus_alpha_prod = sqrt_one_minus_alpha_prod.flatten() | ||
| 473 | while len(sqrt_one_minus_alpha_prod.shape) < len(original_samples.shape): | ||
| 474 | sqrt_one_minus_alpha_prod = sqrt_one_minus_alpha_prod.unsqueeze(-1) | ||
| 475 | |||
| 476 | noisy_samples = sqrt_alpha_prod * original_samples + sqrt_one_minus_alpha_prod * noise | ||
| 477 | return noisy_samples | ||
| 478 | |||
| 479 | def get_velocity( | ||
| 480 | self, sample: torch.FloatTensor, noise: torch.FloatTensor, timesteps: torch.IntTensor | ||
| 481 | ) -> torch.FloatTensor: | ||
| 482 | # Make sure alphas_cumprod and timestep have same device and dtype as sample | ||
| 483 | self.alphas_cumprod = self.alphas_cumprod.to(device=sample.device, dtype=sample.dtype) | ||
| 484 | timesteps = timesteps.to(sample.device) | ||
| 485 | |||
| 486 | sqrt_alpha_prod = self.alphas_cumprod[timesteps] ** 0.5 | ||
| 487 | sqrt_alpha_prod = sqrt_alpha_prod.flatten() | ||
| 488 | while len(sqrt_alpha_prod.shape) < len(sample.shape): | ||
| 489 | sqrt_alpha_prod = sqrt_alpha_prod.unsqueeze(-1) | ||
| 490 | |||
| 491 | sqrt_one_minus_alpha_prod = (1 - self.alphas_cumprod[timesteps]) ** 0.5 | ||
| 492 | sqrt_one_minus_alpha_prod = sqrt_one_minus_alpha_prod.flatten() | ||
| 493 | while len(sqrt_one_minus_alpha_prod.shape) < len(sample.shape): | ||
| 494 | sqrt_one_minus_alpha_prod = sqrt_one_minus_alpha_prod.unsqueeze(-1) | ||
| 495 | |||
| 496 | velocity = sqrt_alpha_prod * noise - sqrt_one_minus_alpha_prod * sample | ||
| 497 | return velocity | ||
| 498 | |||
| 499 | def __len__(self): | ||
| 500 | return self.config.num_train_timesteps | ||
