feat: NCC verify lazy con skip per shape-score alto

ncc_skip_above (default 0.85): se lo score shape e gia molto alto,
salta la verifica NCC (costosa: warp + corr per ogni match). I match
borderline 0.6-0.85 vengono comunque verificati.

Comportamento Halcon-style: NCC come tie-breaker per casi ambigui,
non come gate generalizzato. Su scene con molti match netti riduce
sensibilmente il costo della fase post-NMS.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

pm2d/_jit_kernels.py

@@ -246,22 +246,10 @@ def score_bitmap_rescored(
     return np.maximum(0.0, out).astype(np.float32)
 
 
-_HAS_NP_BITCOUNT = hasattr(np, "bitwise_count")
-
-
 def popcount_density(spread: np.ndarray) -> np.ndarray:
-    """Conta bit set per pixel.
-
-    Order:
-    1) Numba JIT parallel (preferito: piu veloce su 1080p, 0.5ms vs 1.6ms)
-    2) numpy.bitwise_count (NumPy 2.0+, SIMD ma single-thread)
-    3) Fallback numpy bit-shift puro
-    """
-    spread_c = np.ascontiguousarray(spread, dtype=np.uint8)
     if HAS_NUMBA:
-        return _jit_popcount_density(spread_c)
-    if _HAS_NP_BITCOUNT:
-        return np.bitwise_count(spread_c).astype(np.float32, copy=False)
+        return _jit_popcount_density(np.ascontiguousarray(spread, dtype=np.uint8))
+    # Fallback
     H, W = spread.shape
     out = np.zeros((H, W), dtype=np.float32)
     for b in range(8):

pm2d/line_matcher.py

@@ -572,6 +572,7 @@ class LineShapeMatcher:
         subpixel: bool = True,
         verify_ncc: bool = True,
         verify_threshold: float = 0.4,
+        ncc_skip_above: float = 0.85,
         coarse_angle_factor: int = 2,
         scale_penalty: float = 0.0,
     ) -> list[Match]:
@@ -805,7 +806,11 @@ class LineShapeMatcher:
                     search_radius=self.angle_step_deg / 2.0,
                     original_score=score,
                 )
-            if verify_ncc:
+            # NCC verify lazy (Halcon-style): skip se shape-score gia molto
+            # alto (probabilita falso positivo trascurabile). NCC e l'op
+            # piu costosa per match (warp + corr), quindi vale la pena
+            # saltarlo quando il gradiente shape e gia conclusivo.
+            if verify_ncc and float(score_f) < ncc_skip_above:
                 ncc = self._verify_ncc(gray0, cx_f, cy_f, ang_f, var.scale)
                 if ncc < verify_threshold:
                     continue