diff --git a/api/onnx_web/chain/tile.py b/api/onnx_web/chain/tile.py
index 9a294727..bc3a57ab 100644
--- a/api/onnx_web/chain/tile.py
+++ b/api/onnx_web/chain/tile.py
@@ -115,7 +115,7 @@ def make_tile_mask(
 
     # build gradients
     edge_t, edge_l, edge_b, edge_r = edges
-    grad_x, grad_y = [int(edge_l), 1, 1, int(edge_r)], [int(edge_t), 1, 1, int(edge_b)]
+    grad_x, grad_y = [int(not edge_l), 1, 1, int(not edge_r)], [int(not edge_t), 1, 1, int(not edge_b)]
     logger.debug("tile gradients: %s, %s, %s, %s", points_w, points_h, grad_x, grad_y)
 
     mult_x = [np.interp(i, points_w, grad_x) for i in range(tile_w)]