diff --git a/src/diffusers/schedulers/scheduling_deis_multistep.py b/src/diffusers/schedulers/scheduling_deis_multistep.py index 09ce338a9222..b7d64fc00bae 100644 --- a/src/diffusers/schedulers/scheduling_deis_multistep.py +++ b/src/diffusers/schedulers/scheduling_deis_multistep.py @@ -84,33 +84,35 @@ class DEISMultistepScheduler(SchedulerMixin, ConfigMixin): methods the library implements for all schedulers such as loading and saving. Args: - num_train_timesteps (`int`, defaults to 1000): + num_train_timesteps (`int`, defaults to `1000`): The number of diffusion steps to train the model. - beta_start (`float`, defaults to 0.0001): + beta_start (`float`, defaults to `0.0001`): The starting `beta` value of inference. - beta_end (`float`, defaults to 0.02): + beta_end (`float`, defaults to `0.02`): The final `beta` value. - beta_schedule (`str`, defaults to `"linear"`): + beta_schedule (`"linear"`, `"scaled_linear"`, or `"squaredcos_cap_v2"`, defaults to `"linear"`): The beta schedule, a mapping from a beta range to a sequence of betas for stepping the model. Choose from `linear`, `scaled_linear`, or `squaredcos_cap_v2`. - trained_betas (`np.ndarray`, *optional*): + trained_betas (`np.ndarray` or `List[float]`, *optional*): Pass an array of betas directly to the constructor to bypass `beta_start` and `beta_end`. - solver_order (`int`, defaults to 2): + solver_order (`int`, defaults to `2`): The DEIS order which can be `1` or `2` or `3`. It is recommended to use `solver_order=2` for guided sampling, and `solver_order=3` for unconditional sampling. - prediction_type (`str`, defaults to `epsilon`): + prediction_type (`"epsilon"`, `"sample"`, `"v_prediction"`, or `"flow_prediction"`, defaults to `"epsilon"`): Prediction type of the scheduler function; can be `epsilon` (predicts the noise of the diffusion process), - `sample` (directly predicts the noisy sample`) or `v_prediction` (see section 2.4 of [Imagen - Video](https://huggingface.co/papers/2210.02303) paper). + `sample` (directly predicts the noisy sample`), `v_prediction` (see section 2.4 of [Imagen + Video](https://huggingface.co/papers/2210.02303) paper), or `flow_prediction`. thresholding (`bool`, defaults to `False`): Whether to use the "dynamic thresholding" method. This is unsuitable for latent-space diffusion models such as Stable Diffusion. - dynamic_thresholding_ratio (`float`, defaults to 0.995): + dynamic_thresholding_ratio (`float`, defaults to `0.995`): The ratio for the dynamic thresholding method. Valid only when `thresholding=True`. - sample_max_value (`float`, defaults to 1.0): + sample_max_value (`float`, defaults to `1.0`): The threshold value for dynamic thresholding. Valid only when `thresholding=True`. - algorithm_type (`str`, defaults to `deis`): + algorithm_type (`"deis"`, defaults to `"deis"`): The algorithm type for the solver. + solver_type (`"logrho"`, defaults to `"logrho"`): + Solver type for DEIS. lower_order_final (`bool`, defaults to `True`): Whether to use lower-order solvers in the final steps. Only valid for < 15 inference steps. use_karras_sigmas (`bool`, *optional*, defaults to `False`): @@ -121,11 +123,19 @@ class DEISMultistepScheduler(SchedulerMixin, ConfigMixin): use_beta_sigmas (`bool`, *optional*, defaults to `False`): Whether to use beta sigmas for step sizes in the noise schedule during the sampling process. Refer to [Beta Sampling is All You Need](https://huggingface.co/papers/2407.12173) for more information. - timestep_spacing (`str`, defaults to `"linspace"`): + use_flow_sigmas (`bool`, *optional*, defaults to `False`): + Whether to use flow sigmas for step sizes in the noise schedule during the sampling process. + flow_shift (`float`, *optional*, defaults to `1.0`): + The flow shift parameter for flow-based models. + timestep_spacing (`"linspace"`, `"leading"`, or `"trailing"`, defaults to `"linspace"`): The way the timesteps should be scaled. Refer to Table 2 of the [Common Diffusion Noise Schedules and Sample Steps are Flawed](https://huggingface.co/papers/2305.08891) for more information. - steps_offset (`int`, defaults to 0): + steps_offset (`int`, defaults to `0`): An offset added to the inference steps, as required by some model families. + use_dynamic_shifting (`bool`, defaults to `False`): + Whether to use dynamic shifting for the noise schedule. + time_shift_type (`"exponential"`, defaults to `"exponential"`): + The type of time shifting to apply. """ _compatibles = [e.name for e in KarrasDiffusionSchedulers] @@ -137,29 +147,38 @@ def __init__( num_train_timesteps: int = 1000, beta_start: float = 0.0001, beta_end: float = 0.02, - beta_schedule: str = "linear", - trained_betas: Optional[np.ndarray] = None, + beta_schedule: Literal["linear", "scaled_linear", "squaredcos_cap_v2"] = "linear", + trained_betas: Optional[Union[np.ndarray, List[float]]] = None, solver_order: int = 2, - prediction_type: str = "epsilon", + prediction_type: Literal["epsilon", "sample", "v_prediction", "flow_prediction"] = "epsilon", thresholding: bool = False, dynamic_thresholding_ratio: float = 0.995, sample_max_value: float = 1.0, - algorithm_type: str = "deis", - solver_type: str = "logrho", + algorithm_type: Literal["deis"] = "deis", + solver_type: Literal["logrho"] = "logrho", lower_order_final: bool = True, use_karras_sigmas: Optional[bool] = False, use_exponential_sigmas: Optional[bool] = False, use_beta_sigmas: Optional[bool] = False, use_flow_sigmas: Optional[bool] = False, flow_shift: Optional[float] = 1.0, - timestep_spacing: str = "linspace", + timestep_spacing: Literal["linspace", "leading", "trailing"] = "linspace", steps_offset: int = 0, use_dynamic_shifting: bool = False, - time_shift_type: str = "exponential", - ): + time_shift_type: Literal["exponential"] = "exponential", + ) -> None: if self.config.use_beta_sigmas and not is_scipy_available(): raise ImportError("Make sure to install scipy if you want to use beta sigmas.") - if sum([self.config.use_beta_sigmas, self.config.use_exponential_sigmas, self.config.use_karras_sigmas]) > 1: + if ( + sum( + [ + self.config.use_beta_sigmas, + self.config.use_exponential_sigmas, + self.config.use_karras_sigmas, + ] + ) + > 1 + ): raise ValueError( "Only one of `config.use_beta_sigmas`, `config.use_exponential_sigmas`, `config.use_karras_sigmas` can be used." ) @@ -169,7 +188,15 @@ def __init__( self.betas = torch.linspace(beta_start, beta_end, num_train_timesteps, dtype=torch.float32) elif beta_schedule == "scaled_linear": # this schedule is very specific to the latent diffusion model. - self.betas = torch.linspace(beta_start**0.5, beta_end**0.5, num_train_timesteps, dtype=torch.float32) ** 2 + self.betas = ( + torch.linspace( + beta_start**0.5, + beta_end**0.5, + num_train_timesteps, + dtype=torch.float32, + ) + ** 2 + ) elif beta_schedule == "squaredcos_cap_v2": # Glide cosine schedule self.betas = betas_for_alpha_bar(num_train_timesteps) @@ -211,21 +238,21 @@ def __init__( self.sigmas = self.sigmas.to("cpu") # to avoid too much CPU/GPU communication @property - def step_index(self): + def step_index(self) -> Optional[int]: """ The index counter for current timestep. It will increase 1 after each scheduler step. """ return self._step_index @property - def begin_index(self): + def begin_index(self) -> Optional[int]: """ The index for the first timestep. It should be set from pipeline with `set_begin_index` method. """ return self._begin_index # Copied from diffusers.schedulers.scheduling_dpmsolver_multistep.DPMSolverMultistepScheduler.set_begin_index - def set_begin_index(self, begin_index: int = 0): + def set_begin_index(self, begin_index: int = 0) -> None: """ Sets the begin index for the scheduler. This function should be run from pipeline before the inference. @@ -236,8 +263,11 @@ def set_begin_index(self, begin_index: int = 0): self._begin_index = begin_index def set_timesteps( - self, num_inference_steps: int, device: Union[str, torch.device] = None, mu: Optional[float] = None - ): + self, + num_inference_steps: int, + device: Union[str, torch.device] = None, + mu: Optional[float] = None, + ) -> None: """ Sets the discrete timesteps used for the diffusion chain (to be run before inference). @@ -246,6 +276,9 @@ def set_timesteps( The number of diffusion steps used when generating samples with a pre-trained model. device (`str` or `torch.device`, *optional*): The device to which the timesteps should be moved to. If `None`, the timesteps are not moved. + mu (`float`, *optional*): + The mu parameter for dynamic shifting. Only used when `use_dynamic_shifting=True` and + `time_shift_type="exponential"`. """ if mu is not None: assert self.config.use_dynamic_shifting and self.config.time_shift_type == "exponential" @@ -363,7 +396,7 @@ def _threshold_sample(self, sample: torch.Tensor) -> torch.Tensor: return sample # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler._sigma_to_t - def _sigma_to_t(self, sigma, log_sigmas): + def _sigma_to_t(self, sigma: np.ndarray, log_sigmas: np.ndarray) -> np.ndarray: """ Convert sigma values to corresponding timestep values through interpolation. @@ -400,7 +433,7 @@ def _sigma_to_t(self, sigma, log_sigmas): return t # Copied from diffusers.schedulers.scheduling_dpmsolver_multistep.DPMSolverMultistepScheduler._sigma_to_alpha_sigma_t - def _sigma_to_alpha_sigma_t(self, sigma): + def _sigma_to_alpha_sigma_t(self, sigma: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor]: """ Convert sigma values to alpha_t and sigma_t values. @@ -422,7 +455,7 @@ def _sigma_to_alpha_sigma_t(self, sigma): return alpha_t, sigma_t # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler._convert_to_karras - def _convert_to_karras(self, in_sigmas: torch.Tensor, num_inference_steps) -> torch.Tensor: + def _convert_to_karras(self, in_sigmas: torch.Tensor, num_inference_steps: int) -> torch.Tensor: """ Construct the noise schedule as proposed in [Elucidating the Design Space of Diffusion-Based Generative Models](https://huggingface.co/papers/2206.00364). @@ -648,7 +681,10 @@ def deis_first_order_update( "Passing `prev_timestep` is deprecated and has no effect as model output conversion is now handled via an internal counter `self.step_index`", ) - sigma_t, sigma_s = self.sigmas[self.step_index + 1], self.sigmas[self.step_index] + sigma_t, sigma_s = ( + self.sigmas[self.step_index + 1], + self.sigmas[self.step_index], + ) alpha_t, sigma_t = self._sigma_to_alpha_sigma_t(sigma_t) alpha_s, sigma_s = self._sigma_to_alpha_sigma_t(sigma_s) lambda_t = torch.log(alpha_t) - torch.log(sigma_t) @@ -714,7 +750,11 @@ def multistep_deis_second_order_update( m0, m1 = model_output_list[-1], model_output_list[-2] - rho_t, rho_s0, rho_s1 = sigma_t / alpha_t, sigma_s0 / alpha_s0, sigma_s1 / alpha_s1 + rho_t, rho_s0, rho_s1 = ( + sigma_t / alpha_t, + sigma_s0 / alpha_s0, + sigma_s1 / alpha_s1, + ) if self.config.algorithm_type == "deis": @@ -854,7 +894,7 @@ def index_for_timestep( return step_index # Copied from diffusers.schedulers.scheduling_dpmsolver_multistep.DPMSolverMultistepScheduler._init_step_index - def _init_step_index(self, timestep): + def _init_step_index(self, timestep: Union[int, torch.Tensor]) -> None: """ Initialize the step_index counter for the scheduler. @@ -884,18 +924,17 @@ def step( Args: model_output (`torch.Tensor`): The direct output from learned diffusion model. - timestep (`int`): + timestep (`int` or `torch.Tensor`): The current discrete timestep in the diffusion chain. sample (`torch.Tensor`): A current instance of a sample created by the diffusion process. - return_dict (`bool`): + return_dict (`bool`, defaults to `True`): Whether or not to return a [`~schedulers.scheduling_utils.SchedulerOutput`] or `tuple`. Returns: [`~schedulers.scheduling_utils.SchedulerOutput`] or `tuple`: If return_dict is `True`, [`~schedulers.scheduling_utils.SchedulerOutput`] is returned, otherwise a tuple is returned where the first element is the sample tensor. - """ if self.num_inference_steps is None: raise ValueError( @@ -1000,5 +1039,5 @@ def add_noise( noisy_samples = alpha_t * original_samples + sigma_t * noise return noisy_samples - def __len__(self): + def __len__(self) -> int: return self.config.num_train_timesteps