Refactor SchedulerOutput and add pred_original_sample in DPMSolverSDE, Heun, KDPM2Ancestral and KDPM2

src/diffusers/schedulers/scheduling_dpmsolver_sde.py

@@ -13,21 +13,41 @@
 # limitations under the License.
 
 import math
+from dataclasses import dataclass
 from typing import List, Optional, Tuple, Union
 
 import numpy as np
 import torch
 import torchsde
 
 from ..configuration_utils import ConfigMixin, register_to_config
-from ..utils import is_scipy_available
-from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin, SchedulerOutput
+from ..utils import BaseOutput, is_scipy_available
+from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin
 
 
 if is_scipy_available():
     import scipy.stats
 
 
+@dataclass
+# Copied from diffusers.schedulers.scheduling_ddpm.DDPMSchedulerOutput with DDPM->DPMSolverSDE
+class DPMSolverSDESchedulerOutput(BaseOutput):
+    """
+    Output class for the scheduler's `step` function output.
+
+    Args:
+        prev_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            Computed sample `(x_{t-1})` of previous timestep. `prev_sample` should be used as next model input in the
+            denoising loop.
+        pred_original_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            The predicted denoised sample `(x_{0})` based on the model output from the current timestep.
+            `pred_original_sample` can be used to preview progress or for guidance.
+    """
+
+    prev_sample: torch.Tensor
+    pred_original_sample: Optional[torch.Tensor] = None
+
+
 class BatchedBrownianTree:
     """A wrapper around torchsde.BrownianTree that enables batches of entropy."""
 
@@ -510,7 +530,7 @@ def step(
         sample: Union[torch.Tensor, np.ndarray],
         return_dict: bool = True,
         s_noise: float = 1.0,
-    ) -> Union[SchedulerOutput, Tuple]:
+    ) -> Union[DPMSolverSDESchedulerOutput, Tuple]:
         """
         Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
         process from the learned model outputs (most often the predicted noise).
@@ -522,15 +542,16 @@ def step(
                 The current discrete timestep in the diffusion chain.
             sample (`torch.Tensor` or `np.ndarray`):
                 A current instance of a sample created by the diffusion process.
-            return_dict (`bool`, *optional*, defaults to `True`):
-                Whether or not to return a [`~schedulers.scheduling_utils.SchedulerOutput`] or tuple.
+            return_dict (`bool`):
+                Whether or not to return a [`~schedulers.scheduling_dpmsolver_sde.DPMSolverSDESchedulerOutput`] or
+                tuple.
             s_noise (`float`, *optional*, defaults to 1.0):
                 Scaling factor for noise added to the sample.
 
         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.
+            [`~schedulers.scheduling_dpmsolver_sde.DPMSolverSDESchedulerOutput`] or `tuple`:
+                If return_dict is `True`, [`~schedulers.scheduling_dpmsolver_sde.DPMSolverSDESchedulerOutput`] is
+                returned, otherwise a tuple is returned where the first element is the sample tensor.
         """
         if self.step_index is None:
             self._init_step_index(timestep)
@@ -610,9 +631,12 @@ def t_fn(_sigma: torch.Tensor) -> torch.Tensor:
         self._step_index += 1
 
         if not return_dict:
-            return (prev_sample,)
+            return (
+                prev_sample,
+                pred_original_sample,
+            )
 
-        return SchedulerOutput(prev_sample=prev_sample)
+        return DPMSolverSDESchedulerOutput(prev_sample=prev_sample, pred_original_sample=pred_original_sample)
 
     # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler.add_noise
     def add_noise(

src/diffusers/schedulers/scheduling_heun_discrete.py

@@ -13,20 +13,40 @@
 # limitations under the License.
 
 import math
+from dataclasses import dataclass
 from typing import List, Optional, Tuple, Union
 
 import numpy as np
 import torch
 
 from ..configuration_utils import ConfigMixin, register_to_config
-from ..utils import is_scipy_available
-from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin, SchedulerOutput
+from ..utils import BaseOutput, is_scipy_available
+from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin
 
 
 if is_scipy_available():
     import scipy.stats
 
 
+@dataclass
+# Copied from diffusers.schedulers.scheduling_ddpm.DDPMSchedulerOutput with DDPM->HeunDiscrete
+class HeunDiscreteSchedulerOutput(BaseOutput):
+    """
+    Output class for the scheduler's `step` function output.
+
+    Args:
+        prev_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            Computed sample `(x_{t-1})` of previous timestep. `prev_sample` should be used as next model input in the
+            denoising loop.
+        pred_original_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            The predicted denoised sample `(x_{0})` based on the model output from the current timestep.
+            `pred_original_sample` can be used to preview progress or for guidance.
+    """
+
+    prev_sample: torch.Tensor
+    pred_original_sample: Optional[torch.Tensor] = None
+
+
 # Copied from diffusers.schedulers.scheduling_ddpm.betas_for_alpha_bar
 def betas_for_alpha_bar(
     num_diffusion_timesteps,
@@ -455,7 +475,7 @@ def step(
         timestep: Union[float, torch.Tensor],
         sample: Union[torch.Tensor, np.ndarray],
         return_dict: bool = True,
-    ) -> Union[SchedulerOutput, Tuple]:
+    ) -> Union[HeunDiscreteSchedulerOutput, Tuple]:
         """
         Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
         process from the learned model outputs (most often the predicted noise).
@@ -468,12 +488,13 @@ def step(
             sample (`torch.Tensor`):
                 A current instance of a sample created by the diffusion process.
             return_dict (`bool`):
-                Whether or not to return a [`~schedulers.scheduling_utils.SchedulerOutput`] or tuple.
+                Whether or not to return a [`~schedulers.scheduling_heun_discrete.HeunDiscreteSchedulerOutput`] 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.
+            [`~schedulers.scheduling_heun_discrete.HeunDiscreteSchedulerOutput`] or `tuple`:
+                If return_dict is `True`, [`~schedulers.scheduling_heun_discrete.HeunDiscreteSchedulerOutput`] is
+                returned, otherwise a tuple is returned where the first element is the sample tensor.
         """
         if self.step_index is None:
             self._init_step_index(timestep)
@@ -544,9 +565,12 @@ def step(
         self._step_index += 1
 
         if not return_dict:
-            return (prev_sample,)
+            return (
+                prev_sample,
+                pred_original_sample,
+            )
 
-        return SchedulerOutput(prev_sample=prev_sample)
+        return HeunDiscreteSchedulerOutput(prev_sample=prev_sample, pred_original_sample=pred_original_sample)
 
     # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler.add_noise
     def add_noise(

src/diffusers/schedulers/scheduling_k_dpm_2_ancestral_discrete.py

@@ -13,21 +13,41 @@
 # limitations under the License.
 
 import math
+from dataclasses import dataclass
 from typing import List, Optional, Tuple, Union
 
 import numpy as np
 import torch
 
 from ..configuration_utils import ConfigMixin, register_to_config
-from ..utils import is_scipy_available
+from ..utils import BaseOutput, is_scipy_available
 from ..utils.torch_utils import randn_tensor
-from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin, SchedulerOutput
+from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin
 
 
 if is_scipy_available():
     import scipy.stats
 
 
+@dataclass
+# Copied from diffusers.schedulers.scheduling_ddpm.DDPMSchedulerOutput with DDPM->KDPM2AncestralDiscrete
+class KDPM2AncestralDiscreteSchedulerOutput(BaseOutput):
+    """
+    Output class for the scheduler's `step` function output.
+
+    Args:
+        prev_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            Computed sample `(x_{t-1})` of previous timestep. `prev_sample` should be used as next model input in the
+            denoising loop.
+        pred_original_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            The predicted denoised sample `(x_{0})` based on the model output from the current timestep.
+            `pred_original_sample` can be used to preview progress or for guidance.
+    """
+
+    prev_sample: torch.Tensor
+    pred_original_sample: Optional[torch.Tensor] = None
+
+
 # Copied from diffusers.schedulers.scheduling_ddpm.betas_for_alpha_bar
 def betas_for_alpha_bar(
     num_diffusion_timesteps,
@@ -459,7 +479,7 @@ def step(
         sample: Union[torch.Tensor, np.ndarray],
         generator: Optional[torch.Generator] = None,
         return_dict: bool = True,
-    ) -> Union[SchedulerOutput, Tuple]:
+    ) -> Union[KDPM2AncestralDiscreteSchedulerOutput, Tuple]:
         """
         Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
         process from the learned model outputs (most often the predicted noise).
@@ -474,12 +494,14 @@ def step(
             generator (`torch.Generator`, *optional*):
                 A random number generator.
             return_dict (`bool`):
-                Whether or not to return a [`~schedulers.scheduling_utils.SchedulerOutput`] or tuple.
+                Whether or not to return a
+                [`~schedulers.scheduling_k_dpm_2_ancestral_discrete.KDPM2AncestralDiscreteSchedulerOutput`] or tuple.
 
         Returns:
-            [`~schedulers.scheduling_utils.SchedulerOutput`] or `tuple`:
-                If return_dict is `True`, [`~schedulers.scheduling_ddim.SchedulerOutput`] is returned, otherwise a
-                tuple is returned where the first element is the sample tensor.
+            [`~schedulers.scheduling_k_dpm_2_ancestral_discrete.KDPM2AncestralDiscreteSchedulerOutput`] or `tuple`:
+                If return_dict is `True`,
+                [`~schedulers.scheduling_k_dpm_2_ancestral_discrete.KDPM2AncestralDiscreteSchedulerOutput`] is
+                returned, otherwise a tuple is returned where the first element is the sample tensor.
         """
         if self.step_index is None:
             self._init_step_index(timestep)
@@ -548,9 +570,14 @@ def step(
         self._step_index += 1
 
         if not return_dict:
-            return (prev_sample,)
+            return (
+                prev_sample,
+                pred_original_sample,
+            )
 
-        return SchedulerOutput(prev_sample=prev_sample)
+        return KDPM2AncestralDiscreteSchedulerOutput(
+            prev_sample=prev_sample, pred_original_sample=pred_original_sample
+        )
 
     # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler.add_noise
     def add_noise(

src/diffusers/schedulers/scheduling_k_dpm_2_discrete.py

@@ -13,20 +13,40 @@
 # limitations under the License.
 
 import math
+from dataclasses import dataclass
 from typing import List, Optional, Tuple, Union
 
 import numpy as np
 import torch
 
 from ..configuration_utils import ConfigMixin, register_to_config
-from ..utils import is_scipy_available
-from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin, SchedulerOutput
+from ..utils import BaseOutput, is_scipy_available
+from .scheduling_utils import KarrasDiffusionSchedulers, SchedulerMixin
 
 
 if is_scipy_available():
     import scipy.stats
 
 
+@dataclass
+# Copied from diffusers.schedulers.scheduling_ddpm.DDPMSchedulerOutput with DDPM->KDPM2Discrete
+class KDPM2DiscreteSchedulerOutput(BaseOutput):
+    """
+    Output class for the scheduler's `step` function output.
+
+    Args:
+        prev_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            Computed sample `(x_{t-1})` of previous timestep. `prev_sample` should be used as next model input in the
+            denoising loop.
+        pred_original_sample (`torch.Tensor` of shape `(batch_size, num_channels, height, width)` for images):
+            The predicted denoised sample `(x_{0})` based on the model output from the current timestep.
+            `pred_original_sample` can be used to preview progress or for guidance.
+    """
+
+    prev_sample: torch.Tensor
+    pred_original_sample: Optional[torch.Tensor] = None
+
+
 # Copied from diffusers.schedulers.scheduling_ddpm.betas_for_alpha_bar
 def betas_for_alpha_bar(
     num_diffusion_timesteps,
@@ -443,7 +463,7 @@ def step(
         timestep: Union[float, torch.Tensor],
         sample: Union[torch.Tensor, np.ndarray],
         return_dict: bool = True,
-    ) -> Union[SchedulerOutput, Tuple]:
+    ) -> Union[KDPM2DiscreteSchedulerOutput, Tuple]:
         """
         Predict the sample from the previous timestep by reversing the SDE. This function propagates the diffusion
         process from the learned model outputs (most often the predicted noise).
@@ -456,12 +476,13 @@ def step(
             sample (`torch.Tensor`):
                 A current instance of a sample created by the diffusion process.
             return_dict (`bool`):
-                Whether or not to return a [`~schedulers.scheduling_utils.SchedulerOutput`] or tuple.
+                Whether or not to return a [`~schedulers.scheduling_k_dpm_2_discrete.KDPM2DiscreteSchedulerOutput`] 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.
+            [`~schedulers.scheduling_k_dpm_2_discrete.KDPM2DiscreteSchedulerOutput`] or `tuple`:
+                If return_dict is `True`, [`~schedulers.scheduling_k_dpm_2_discrete.KDPM2DiscreteSchedulerOutput`] is
+                returned, otherwise a tuple is returned where the first element is the sample tensor.
         """
         if self.step_index is None:
             self._init_step_index(timestep)
@@ -523,9 +544,12 @@ def step(
         prev_sample = sample + derivative * dt
 
         if not return_dict:
-            return (prev_sample,)
+            return (
+                prev_sample,
+                pred_original_sample,
+            )
 
-        return SchedulerOutput(prev_sample=prev_sample)
+        return KDPM2DiscreteSchedulerOutput(prev_sample=prev_sample, pred_original_sample=pred_original_sample)
 
     # Copied from diffusers.schedulers.scheduling_euler_discrete.EulerDiscreteScheduler.add_noise
     def add_noise(