Make the LoadImage node output the alpha as a mask.

nodes.py

@@ -815,7 +815,7 @@ class LoadImage:
 
     CATEGORY = "image"
 
-    RETURN_TYPES = ("IMAGE",)
+    RETURN_TYPES = ("IMAGE", "MASK")
     FUNCTION = "load_image"
     def load_image(self, image):
         image_path = os.path.join(self.input_dir, image)
@@ -823,7 +823,12 @@ class LoadImage:
         image = i.convert("RGB")
         image = np.array(image).astype(np.float32) / 255.0
         image = torch.from_numpy(image)[None,]
-        return (image,)
+        if 'A' in i.getbands():
+            mask = np.array(i.getchannel('A')).astype(np.float32) / 255.0
+            mask = 1. - torch.from_numpy(mask)
+        else:
+            mask = torch.zeros((64,64), dtype=torch.float32, device="cpu")
+        return (image, mask)
 
     @classmethod
     def IS_CHANGED(s, image):