Allow ApplyMaskToImage handle multiple masks (#11)

* Allow ApplyMaskToImage handle multiple masks

nodes.py

@@ -131,11 +131,30 @@ class ApplyMaskToImage:
     RETURN_TYPES = ("IMAGE",)
     FUNCTION = "apply_mask"
 
-    def apply_mask(self, image, mask):
+    def apply_mask(self, image: torch.Tensor, mask: torch.Tensor):
+        # Move the channel to the second dimension for processing
         out = image.movedim(-1, 1)
-        if out.shape[1] == 3:  # RGB
+
+        # Check if the images are RGB, and if so, add an alpha channel initialized to 1
+        if out.shape[1] == 3:  # Assuming RGB images
             out = torch.cat([out, torch.ones_like(out[:, :1, :, :])], dim=1)
+
+        # Ensure masks are unsqueezed to match the alpha channel dimension if needed
+        if mask.ndim == 2:
+            mask = mask.unsqueeze(0)  # Add a batch dimension to masks
+        # For single mask, expand it to match size of image batch size.
+        if mask.shape[0] == 1:
+            mask = mask.repeat(out.shape[0], 1, 1)
+
+        assert mask.ndim == 3, f"Mask should have shape [B, H, W]. {mask.shape}"
+        assert out.ndim == 4, f"Image should have shsape [B, C, H, W]. {out.shape}"
+        assert out.shape[-2:] == mask.shape[-2:], f"{out.shape[-2:]} != {mask.shape[-2:]}"
+        assert out.shape[0] == mask.shape[0], f"{out.shape[0]} != {mask.shape[0]}"
+        # Apply each mask in the batch to its corresponding image's alpha channel
         for i in range(out.shape[0]):
-            out[i, 3, :, :] = mask
+            out[i, 3, :, :] = mask[i]
+
+        # Move the channel back to its original dimension
         out = out.movedim(1, -1)
+
         return (out,)