""" 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) # print('denoised', denoised.mean(axis=[0, 2, 3])) 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 ): # print("euler_step: ", euler_step.mean(axis=[0, 2, 3])) 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 class RestoreEDMSampler(SingleStepDiffusionSampler): def __init__( self, s_churn=0.0, s_tmin=0.0, s_tmax=float("inf"), s_noise=1.0, restore_cfg=4.0, restore_cfg_s_tmin=0.05, *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 self.restore_cfg = restore_cfg self.restore_cfg_s_tmin = restore_cfg_s_tmin self.sigma_max = 14.6146 def denoise(self, x, denoiser, sigma, cond, uc, control_scale=1.0): denoised = denoiser(*self.guider.prepare_inputs(x, sigma, cond, uc), control_scale) denoised = self.guider(denoised, sigma) return denoised def sampler_step(self, sigma, next_sigma, denoiser, x, cond, uc=None, gamma=0.0, x_center=None, eps_noise=None, control_scale=1.0, use_linear_control_scale=False, control_scale_start=0.0): sigma_hat = sigma * (gamma + 1.0) if gamma > 0: if eps_noise is not None: eps = eps_noise * self.s_noise else: eps = torch.randn_like(x) * self.s_noise x = x + eps * append_dims(sigma_hat**2 - sigma**2, x.ndim) ** 0.5 if use_linear_control_scale: control_scale = (sigma[0].item() / self.sigma_max) * (control_scale_start - control_scale) + control_scale denoised = self.denoise(x, denoiser, sigma_hat, cond, uc, control_scale=control_scale) if (next_sigma[0] > self.restore_cfg_s_tmin) and (self.restore_cfg > 0): d_center = (denoised - x_center) denoised = denoised - d_center * ((sigma.view(-1, 1, 1, 1) / self.sigma_max) ** self.restore_cfg) d = to_d(x, sigma_hat, denoised) dt = append_dims(next_sigma - sigma_hat, x.ndim) x = self.euler_step(x, d, dt) return x def __call__(self, denoiser, x, cond, uc=None, num_steps=None, x_center=None, control_scale=1.0, use_linear_control_scale=False, control_scale_start=0.0): x, s_in, sigmas, num_sigmas, cond, uc = self.prepare_sampling_loop( x, cond, uc, num_steps ) for _idx, i in enumerate(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, x_center, control_scale=control_scale, use_linear_control_scale=use_linear_control_scale, control_scale_start=control_scale_start, ) return x def to_d_center(denoised, x_center, x): b = denoised.shape[0] v_center = (denoised - x_center).view(b, -1) v_denoise = (x - denoised).view(b, -1) d_center = v_center - v_denoise * (v_center * v_denoise).sum(dim=1).view(b, 1) / \ (v_denoise * v_denoise).sum(dim=1).view(b, 1) d_center = d_center / d_center.view(x.shape[0], -1).norm(dim=1).view(-1, 1) return d_center.view(denoised.shape)