Make Batch Images node add alpha channel when one of the inputs has it (#10816)

* When one Batch Image input has alpha and one does not, add empty alpha channel

* Use torch.nn.functional.pad

Author: Kosinkadink

nodes.py

@@ -1853,9 +1853,10 @@ def INPUT_TYPES(s):
 
     def batch(self, image1, image2):
         if image1.shape[-1] != image2.shape[-1]:
-            channels = min(image1.shape[-1], image2.shape[-1])
-            image1 = image1[..., :channels]
-            image2 = image2[..., :channels]
+            if image1.shape[-1] > image2.shape[-1]:
+                image2 = torch.nn.functional.pad(image2, (0,1), mode='constant', value=1.0)
+            else:
+                image1 = torch.nn.functional.pad(image1, (0,1), mode='constant', value=1.0)
         if image1.shape[1:] != image2.shape[1:]:
             image2 = comfy.utils.common_upscale(image2.movedim(-1,1), image1.shape[2], image1.shape[1], "bilinear", "center").movedim(1,-1)
         s = torch.cat((image1, image2), dim=0)