feat(nodes): add freeu support

Add support for FreeU. See:
- https://huggingface.co/docs/diffusers/main/en/using-diffusers/freeu
- https://github.com/ChenyangSi/FreeU

Implementation:
- `ModelPatcher.apply_freeu()` handles the enabling freeu (which is very simple with diffusers).
- `FreeUConfig` model added to hold the hyperparameters.
- `freeu_config` added as optional sub-field on `UNetField`.
- `FreeUInvocation` added, works like LoRA - chain it to add the FreeU config to the UNet
- No support for model-dependent presets, this will be a future workflow editor enhancement

Closes #4845

invokeai/app/invocations/model.py

@@ -3,6 +3,8 @@ from typing import List, Optional
 
 from pydantic import BaseModel, Field
 
+from invokeai.app.invocations.shared import FreeUConfig
+
 from ...backend.model_management import BaseModelType, ModelType, SubModelType
 from .baseinvocation import (
     BaseInvocation,
@@ -34,6 +36,7 @@ class UNetField(BaseModel):
     scheduler: ModelInfo = Field(description="Info to load scheduler submodel")
     loras: List[LoraInfo] = Field(description="Loras to apply on model loading")
     seamless_axes: List[str] = Field(default_factory=list, description='Axes("x" and "y") to which apply seamless')
+    freeu_config: Optional[FreeUConfig] = Field(default=None, description="FreeU configuration")
 
 
 class ClipField(BaseModel):
@@ -49,15 +52,34 @@ class VaeField(BaseModel):
     seamless_axes: List[str] = Field(default_factory=list, description='Axes("x" and "y") to which apply seamless')
 
 
-@invocation_output("model_loader_output")
-class ModelLoaderOutput(BaseInvocationOutput):
-    """Model loader output"""
+@invocation_output("unet_output")
+class UNetOutput(BaseInvocationOutput):
+    """Base class for invocations that output a UNet field"""
 
     unet: UNetField = OutputField(description=FieldDescriptions.unet, title="UNet")
-    clip: ClipField = OutputField(description=FieldDescriptions.clip, title="CLIP")
+
+
+@invocation_output("vae_output")
+class VAEOutput(BaseInvocationOutput):
+    """Base class for invocations that output a VAE field"""
+
     vae: VaeField = OutputField(description=FieldDescriptions.vae, title="VAE")
 
 
+@invocation_output("clip_output")
+class CLIPOutput(BaseInvocationOutput):
+    """Base class for invocations that output a CLIP field"""
+
+    clip: ClipField = OutputField(description=FieldDescriptions.clip, title="CLIP")
+
+
+@invocation_output("model_loader_output")
+class ModelLoaderOutput(UNetOutput, CLIPOutput, VAEOutput):
+    """Model loader output"""
+
+    pass
+
+
 class MainModelField(BaseModel):
     """Main model field"""
 
@@ -331,13 +353,6 @@ class VAEModelField(BaseModel):
     base_model: BaseModelType = Field(description="Base model")
 
 
-@invocation_output("vae_loader_output")
-class VaeLoaderOutput(BaseInvocationOutput):
-    """VAE output"""
-
-    vae: VaeField = OutputField(description=FieldDescriptions.vae, title="VAE")
-
-
 @invocation("vae_loader", title="VAE", tags=["vae", "model"], category="model", version="1.0.0")
 class VaeLoaderInvocation(BaseInvocation):
     """Loads a VAE model, outputting a VaeLoaderOutput"""
@@ -346,7 +361,7 @@ class VaeLoaderInvocation(BaseInvocation):
         description=FieldDescriptions.vae_model, input=Input.Direct, ui_type=UIType.VaeModel, title="VAE"
     )
 
-    def invoke(self, context: InvocationContext) -> VaeLoaderOutput:
+    def invoke(self, context: InvocationContext) -> VAEOutput:
         base_model = self.vae_model.base_model
         model_name = self.vae_model.model_name
         model_type = ModelType.Vae
@@ -357,7 +372,7 @@ class VaeLoaderInvocation(BaseInvocation):
             model_type=model_type,
         ):
             raise Exception(f"Unkown vae name: {model_name}!")
-        return VaeLoaderOutput(
+        return VAEOutput(
             vae=VaeField(
                 vae=ModelInfo(
                     model_name=model_name,
@@ -407,3 +422,24 @@ class SeamlessModeInvocation(BaseInvocation):
             vae.seamless_axes = seamless_axes_list
 
         return SeamlessModeOutput(unet=unet, vae=vae)
+
+
+@invocation("freeu", title="FreeU", tags=["freeu"], category="unet", version="1.0.0")
+class FreeUInvocation(BaseInvocation):
+    """
+    Applies FreeU to the UNet. Suggested values (b1/b2/s1/s2):
+
+    SD1.5: 1.2/1.4/0.9/0.2,
+    SD2: 1.1/1.2/0.9/0.2,
+    SDXL: 1.1/1.2/0.6/0.4,
+    """
+
+    unet: UNetField = InputField(description=FieldDescriptions.unet, input=Input.Connection, title="UNet")
+    b1: float = InputField(default=1.2, ge=-1, le=3, description=FieldDescriptions.freeu_b1)
+    b2: float = InputField(default=1.4, ge=-1, le=3, description=FieldDescriptions.freeu_b2)
+    s1: float = InputField(default=0.9, ge=-1, le=3, description=FieldDescriptions.freeu_s1)
+    s2: float = InputField(default=0.2, ge=-1, le=3, description=FieldDescriptions.freeu_s2)
+
+    def invoke(self, context: InvocationContext) -> UNetOutput:
+        self.unet.freeu_config = FreeUConfig(s1=self.s1, s2=self.s2, b1=self.b1, b2=self.b2)
+        return UNetOutput(unet=self.unet)