diff --git a/pm2d/web/server.py b/pm2d/web/server.py
index 0a1e0de..94b0db4 100644
--- a/pm2d/web/server.py
+++ b/pm2d/web/server.py
@@ -161,7 +161,10 @@ def _draw_matches(scene: np.ndarray, matches: list[Match],
         cx, cy = int(round(m.cx)), int(round(m.cy))
         # Overlay edge del modello orientato (richiesta utente):
         # warpa template alla pose, applica hysteresis identica al matcher,
-        # disegna pixel edge come overlay verde tenue.
+        # disegna pixel edge come overlay verde tenue. Maschera col
+        # _train_mask warpato + erode per rimuovere edge sui BORDI del
+        # rettangolo template (transizione bordo nero → scena = falso edge
+        # che appariva come "ROI" attorno a ogni match).
         if template_gray is not None and matcher is not None:
             t = template_gray
             th, tw = t.shape
@@ -172,11 +175,23 @@ def _draw_matches(scene: np.ndarray, matches: list[Match],
             warped_gray = cv2.warpAffine(
                 t, M, (W_scene, H_scene),
                 flags=cv2.INTER_LINEAR, borderValue=0)
+            # Maschera: train_mask se disponibile, altrimenti rettangolo pieno
+            mask_src = (matcher._train_mask if matcher._train_mask is not None
+                        else np.full((th, tw), 255, dtype=np.uint8))
+            warped_mask = cv2.warpAffine(
+                mask_src, M, (W_scene, H_scene),
+                flags=cv2.INTER_NEAREST, borderValue=0)
+            # Erode di spread_radius per scartare la fascia di transizione
+            # bordo che produce gradient spurio
+            er_k = max(3, 2 * matcher.spread_radius + 1)
+            kernel_er = np.ones((er_k, er_k), np.uint8)
+            warped_mask = cv2.erode(warped_mask, kernel_er)
             mag, _ = matcher._gradient(warped_gray)
             if matcher.weak_grad < matcher.strong_grad:
                 edge_mask = matcher._hysteresis_mask(mag)
             else:
                 edge_mask = mag >= matcher.strong_grad
+            edge_mask = edge_mask & (warped_mask > 0)
             if edge_mask.any():
                 edge_overlay = np.zeros_like(out)
                 edge_overlay[edge_mask] = (0, 220, 0)  # verde brillante