Re-order GroundedSAMInvocation._to_numpy_masks(...) to do slightly more work on the GPU.

Author: RyanJDick

invokeai/app/invocations/grounded_sam.py

@@ -156,11 +156,11 @@ def _segment(
 
     def _to_numpy_masks(self, masks: torch.Tensor) -> list[npt.NDArray[np.uint8]]:
         """Convert the tensor output from the Segment Anything model to a list of numpy masks."""
-        masks = masks.cpu().float()
-        masks = masks.permute(0, 2, 3, 1)
-        masks = masks.mean(dim=-1)
-        masks = (masks > 0).int()
-        np_masks = masks.numpy().astype(np.uint8)
+        eps = 0.0001
+        # [num_masks, channels, height, width] -> [num_masks, height, width]
+        masks = masks.permute(0, 2, 3, 1).float().mean(dim=-1)
+        masks = masks > eps
+        np_masks = masks.cpu().numpy().astype(np.uint8)
         return list(np_masks)
 
     def _apply_polygon_refinement(self, masks: list[npt.NDArray[np.uint8]]) -> list[npt.NDArray[np.uint8]]: