Add global pooling to controlnet (huggingface#3121)

Author: patrickvonplaten

src/diffusers/models/controlnet.py

@@ -119,6 +119,7 @@ def __init__(
         projection_class_embeddings_input_dim: Optional[int] = None,
         controlnet_conditioning_channel_order: str = "rgb",
         conditioning_embedding_out_channels: Optional[Tuple[int]] = (16, 32, 96, 256),
+        global_pool_conditions: bool = False,
     ):
         super().__init__()
 
@@ -566,6 +567,12 @@ def forward(
             down_block_res_samples = [sample * conditioning_scale for sample in down_block_res_samples]
             mid_block_res_sample *= conditioning_scale
 
+        if self.config.global_pool_conditions:
+            down_block_res_samples = [
+                torch.mean(sample, dim=(2, 3), keepdim=True) for sample in down_block_res_samples
+            ]
+            mid_block_res_sample = torch.mean(mid_block_res_sample, dim=(2, 3), keepdim=True)
+
         if not return_dict:
             return (down_block_res_samples, mid_block_res_sample)