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on
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Running
on
Zero
| """ | |
| Partially ported from https://github.com/crowsonkb/k-diffusion/blob/master/k_diffusion/sampling.py | |
| """ | |
| from typing import Dict, Union | |
| import torch | |
| from omegaconf import ListConfig, OmegaConf | |
| from tqdm import tqdm | |
| from ...modules.diffusionmodules.sampling_utils import ( | |
| get_ancestral_step, | |
| linear_multistep_coeff, | |
| to_d, | |
| to_neg_log_sigma, | |
| to_sigma, | |
| ) | |
| from ...util import append_dims, default, instantiate_from_config | |
| DEFAULT_GUIDER = {"target": "sgm.modules.diffusionmodules.guiders.IdentityGuider"} | |
| class BaseDiffusionSampler: | |
| def __init__( | |
| self, | |
| discretization_config: Union[Dict, ListConfig, OmegaConf], | |
| num_steps: Union[int, None] = None, | |
| guider_config: Union[Dict, ListConfig, OmegaConf, None] = None, | |
| verbose: bool = False, | |
| device: str = "cuda", | |
| ): | |
| self.num_steps = num_steps | |
| self.discretization = instantiate_from_config(discretization_config) | |
| self.guider = instantiate_from_config( | |
| default( | |
| guider_config, | |
| DEFAULT_GUIDER, | |
| ) | |
| ) | |
| self.verbose = verbose | |
| self.device = device | |
| def prepare_sampling_loop(self, x, cond, uc=None, num_steps=None): | |
| sigmas = self.discretization( | |
| self.num_steps if num_steps is None else num_steps, device=self.device | |
| ) | |
| uc = default(uc, cond) | |
| x *= torch.sqrt(1.0 + sigmas[0] ** 2.0) | |
| num_sigmas = len(sigmas) | |
| s_in = x.new_ones([x.shape[0]]) | |
| return x, s_in, sigmas, num_sigmas, cond, uc | |
| def denoise(self, x, denoiser, sigma, cond, uc): | |
| denoised = denoiser(*self.guider.prepare_inputs(x, sigma, cond, uc)) | |
| denoised = self.guider(denoised, sigma) | |
| return denoised | |
| def get_sigma_gen(self, num_sigmas): | |
| sigma_generator = range(num_sigmas - 1) | |
| if self.verbose: | |
| print("#" * 30, " Sampling setting ", "#" * 30) | |
| print(f"Sampler: {self.__class__.__name__}") | |
| print(f"Discretization: {self.discretization.__class__.__name__}") | |
| print(f"Guider: {self.guider.__class__.__name__}") | |
| sigma_generator = tqdm( | |
| sigma_generator, | |
| total=num_sigmas, | |
| desc=f"Sampling with {self.__class__.__name__} for {num_sigmas} steps", | |
| ) | |
| return sigma_generator | |
| class SingleStepDiffusionSampler(BaseDiffusionSampler): | |
| def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc, *args, **kwargs): | |
| raise NotImplementedError | |
| def euler_step(self, x, d, dt): | |
| return x + dt * d | |
| class EDMSampler(SingleStepDiffusionSampler): | |
| def __init__( | |
| self, s_churn=0.0, s_tmin=0.0, s_tmax=float("inf"), s_noise=1.0, *args, **kwargs | |
| ): | |
| super().__init__(*args, **kwargs) | |
| self.s_churn = s_churn | |
| self.s_tmin = s_tmin | |
| self.s_tmax = s_tmax | |
| self.s_noise = s_noise | |
| def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc=None, gamma=0.0): | |
| sigma_hat = sigma * (gamma + 1.0) | |
| if gamma > 0: | |
| eps = torch.randn_like(x) * self.s_noise | |
| x = x + eps * append_dims(sigma_hat**2 - sigma**2, x.ndim) ** 0.5 | |
| denoised = self.denoise(x, denoiser, sigma_hat, cond, uc) | |
| d = to_d(x, sigma_hat, denoised) | |
| dt = append_dims(next_sigma - sigma_hat, x.ndim) | |
| euler_step = self.euler_step(x, d, dt) | |
| x = self.possible_correction_step( | |
| euler_step, x, d, dt, next_sigma, denoiser, cond, uc | |
| ) | |
| return x | |
| def __call__(self, denoiser, x, cond, uc=None, num_steps=None): | |
| x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop( | |
| x, cond, uc, num_steps | |
| ) | |
| for i in self.get_sigma_gen(num_sigmas): | |
| gamma = ( | |
| min(self.s_churn / (num_sigmas - 1), 2**0.5 - 1) | |
| if self.s_tmin <= sigmas[i] <= self.s_tmax | |
| else 0.0 | |
| ) | |
| x = self.sampler_step( | |
| s_in * sigmas[i], | |
| s_in * sigmas[i + 1], | |
| denoiser, | |
| x, | |
| cond, | |
| uc, | |
| gamma, | |
| ) | |
| return x | |
| class AncestralSampler(SingleStepDiffusionSampler): | |
| def __init__(self, eta=1.0, s_noise=1.0, *args, **kwargs): | |
| super().__init__(*args, **kwargs) | |
| self.eta = eta | |
| self.s_noise = s_noise | |
| self.noise_sampler = lambda x: torch.randn_like(x) | |
| def ancestral_euler_step(self, x, denoised, sigma, sigma_down): | |
| d = to_d(x, sigma, denoised) | |
| dt = append_dims(sigma_down - sigma, x.ndim) | |
| return self.euler_step(x, d, dt) | |
| def ancestral_step(self, x, sigma, next_sigma, sigma_up): | |
| x = torch.where( | |
| append_dims(next_sigma, x.ndim) > 0.0, | |
| x + self.noise_sampler(x) * self.s_noise * append_dims(sigma_up, x.ndim), | |
| x, | |
| ) | |
| return x | |
| def __call__(self, denoiser, x, cond, uc=None, num_steps=None): | |
| x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop( | |
| x, cond, uc, num_steps | |
| ) | |
| for i in self.get_sigma_gen(num_sigmas): | |
| x = self.sampler_step( | |
| s_in * sigmas[i], | |
| s_in * sigmas[i + 1], | |
| denoiser, | |
| x, | |
| cond, | |
| uc, | |
| ) | |
| return x | |
| class LinearMultistepSampler(BaseDiffusionSampler): | |
| def __init__( | |
| self, | |
| order=4, | |
| *args, | |
| **kwargs, | |
| ): | |
| super().__init__(*args, **kwargs) | |
| self.order = order | |
| def __call__(self, denoiser, x, cond, uc=None, num_steps=None, **kwargs): | |
| x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop( | |
| x, cond, uc, num_steps | |
| ) | |
| ds = [] | |
| sigmas_cpu = sigmas.detach().cpu().numpy() | |
| for i in self.get_sigma_gen(num_sigmas): | |
| sigma = s_in * sigmas[i] | |
| denoised = denoiser( | |
| *self.guider.prepare_inputs(x, sigma, cond, uc), **kwargs | |
| ) | |
| denoised = self.guider(denoised, sigma) | |
| d = to_d(x, sigma, denoised) | |
| ds.append(d) | |
| if len(ds) > self.order: | |
| ds.pop(0) | |
| cur_order = min(i + 1, self.order) | |
| coeffs = [ | |
| linear_multistep_coeff(cur_order, sigmas_cpu, i, j) | |
| for j in range(cur_order) | |
| ] | |
| x = x + sum(coeff * d for coeff, d in zip(coeffs, reversed(ds))) | |
| return x | |
| class EulerEDMSampler(EDMSampler): | |
| def possible_correction_step( | |
| self, euler_step, x, d, dt, next_sigma, denoiser, cond, uc | |
| ): | |
| return euler_step | |
| class HeunEDMSampler(EDMSampler): | |
| def possible_correction_step( | |
| self, euler_step, x, d, dt, next_sigma, denoiser, cond, uc | |
| ): | |
| if torch.sum(next_sigma) < 1e-14: | |
| # Save a network evaluation if all noise levels are 0 | |
| return euler_step | |
| else: | |
| denoised = self.denoise(euler_step, denoiser, next_sigma, cond, uc) | |
| d_new = to_d(euler_step, next_sigma, denoised) | |
| d_prime = (d + d_new) / 2.0 | |
| # apply correction if noise level is not 0 | |
| x = torch.where( | |
| append_dims(next_sigma, x.ndim) > 0.0, x + d_prime * dt, euler_step | |
| ) | |
| return x | |
| class EulerAncestralSampler(AncestralSampler): | |
| def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc): | |
| sigma_down, sigma_up = get_ancestral_step(sigma, next_sigma, eta=self.eta) | |
| denoised = self.denoise(x, denoiser, sigma, cond, uc) | |
| x = self.ancestral_euler_step(x, denoised, sigma, sigma_down) | |
| x = self.ancestral_step(x, sigma, next_sigma, sigma_up) | |
| return x | |
| class DPMPP2SAncestralSampler(AncestralSampler): | |
| def get_variables(self, sigma, sigma_down): | |
| t, t_next = [to_neg_log_sigma(s) for s in (sigma, sigma_down)] | |
| h = t_next - t | |
| s = t + 0.5 * h | |
| return h, s, t, t_next | |
| def get_mult(self, h, s, t, t_next): | |
| mult1 = to_sigma(s) / to_sigma(t) | |
| mult2 = (-0.5 * h).expm1() | |
| mult3 = to_sigma(t_next) / to_sigma(t) | |
| mult4 = (-h).expm1() | |
| return mult1, mult2, mult3, mult4 | |
| def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc=None, **kwargs): | |
| sigma_down, sigma_up = get_ancestral_step(sigma, next_sigma, eta=self.eta) | |
| denoised = self.denoise(x, denoiser, sigma, cond, uc) | |
| x_euler = self.ancestral_euler_step(x, denoised, sigma, sigma_down) | |
| if torch.sum(sigma_down) < 1e-14: | |
| # Save a network evaluation if all noise levels are 0 | |
| x = x_euler | |
| else: | |
| h, s, t, t_next = self.get_variables(sigma, sigma_down) | |
| mult = [ | |
| append_dims(mult, x.ndim) for mult in self.get_mult(h, s, t, t_next) | |
| ] | |
| x2 = mult[0] * x - mult[1] * denoised | |
| denoised2 = self.denoise(x2, denoiser, to_sigma(s), cond, uc) | |
| x_dpmpp2s = mult[2] * x - mult[3] * denoised2 | |
| # apply correction if noise level is not 0 | |
| x = torch.where(append_dims(sigma_down, x.ndim) > 0.0, x_dpmpp2s, x_euler) | |
| x = self.ancestral_step(x, sigma, next_sigma, sigma_up) | |
| return x | |
| class DPMPP2MSampler(BaseDiffusionSampler): | |
| def get_variables(self, sigma, next_sigma, previous_sigma=None): | |
| t, t_next = [to_neg_log_sigma(s) for s in (sigma, next_sigma)] | |
| h = t_next - t | |
| if previous_sigma is not None: | |
| h_last = t - to_neg_log_sigma(previous_sigma) | |
| r = h_last / h | |
| return h, r, t, t_next | |
| else: | |
| return h, None, t, t_next | |
| def get_mult(self, h, r, t, t_next, previous_sigma): | |
| mult1 = to_sigma(t_next) / to_sigma(t) | |
| mult2 = (-h).expm1() | |
| if previous_sigma is not None: | |
| mult3 = 1 + 1 / (2 * r) | |
| mult4 = 1 / (2 * r) | |
| return mult1, mult2, mult3, mult4 | |
| else: | |
| return mult1, mult2 | |
| def sampler_step( | |
| self, | |
| old_denoised, | |
| previous_sigma, | |
| sigma, | |
| next_sigma, | |
| denoiser, | |
| x, | |
| cond, | |
| uc=None, | |
| ): | |
| denoised = self.denoise(x, denoiser, sigma, cond, uc) | |
| h, r, t, t_next = self.get_variables(sigma, next_sigma, previous_sigma) | |
| mult = [ | |
| append_dims(mult, x.ndim) | |
| for mult in self.get_mult(h, r, t, t_next, previous_sigma) | |
| ] | |
| x_standard = mult[0] * x - mult[1] * denoised | |
| if old_denoised is None or torch.sum(next_sigma) < 1e-14: | |
| # Save a network evaluation if all noise levels are 0 or on the first step | |
| return x_standard, denoised | |
| else: | |
| denoised_d = mult[2] * denoised - mult[3] * old_denoised | |
| x_advanced = mult[0] * x - mult[1] * denoised_d | |
| # apply correction if noise level is not 0 and not first step | |
| x = torch.where( | |
| append_dims(next_sigma, x.ndim) > 0.0, x_advanced, x_standard | |
| ) | |
| return x, denoised | |
| def __call__(self, denoiser, x, cond, uc=None, num_steps=None, **kwargs): | |
| x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop( | |
| x, cond, uc, num_steps | |
| ) | |
| old_denoised = None | |
| for i in self.get_sigma_gen(num_sigmas): | |
| x, old_denoised = self.sampler_step( | |
| old_denoised, | |
| None if i == 0 else s_in * sigmas[i - 1], | |
| s_in * sigmas[i], | |
| s_in * sigmas[i + 1], | |
| denoiser, | |
| x, | |
| cond, | |
| uc=uc, | |
| ) | |
| return x | |