Fix SplitImageWithAlpha and JoinImageWithAlpha.

comfy_extras/nodes_compositing.py

@@ -158,7 +158,7 @@ class SplitImageWithAlpha:
     def split_image_with_alpha(self, image: torch.Tensor):
         out_images = [i[:,:,:3] for i in image]
         out_alphas = [i[:,:,3] if i.shape[2] > 3 else torch.ones_like(i[:,:,0]) for i in image]
-        result = (torch.stack(out_images), torch.stack(out_alphas))
+        result = (torch.stack(out_images), 1.0 - torch.stack(out_alphas))
         return result
 
 
@@ -180,7 +180,7 @@ class JoinImageWithAlpha:
         batch_size = min(len(image), len(alpha))
         out_images = []
 
-        alpha = resize_mask(alpha, image.shape[1:])
+        alpha = 1.0 - resize_mask(alpha, image.shape[1:])
         for i in range(batch_size):
            out_images.append(torch.cat((image[i][:,:,:3], alpha[i].unsqueeze(2)), dim=2))