Local Median Color Boundary

app.py

@@ -56,16 +56,53 @@ def _process_saree_core(base_image: Image.Image, pattern_image: Image.Image):
     # img_pil = base_image.convert("RGB")  # <-- COMMENTED: this injects black behind transparency
     # img_np = np.array(img_pil)
 
-    # --- NEW: alpha-aware RGB (composite RGBA over white to avoid black fringe) ---
+    # --- ORIGINAL (white matte) kept for reference ---
+    # base_rgba = base_image.convert("RGBA")
+    # _arr = np.array(base_rgba).astype(np.float32)
+    # _rgb = _arr[..., :3]
+    # _a = (_arr[..., 3:4] / 255.0)
+    # _rgb_over_white = _rgb * _a + (1.0 - _a) * 255.0
+    # _rgb_over_white = _rgb_over_white.astype(np.uint8)
+    # img_pil = Image.fromarray(_rgb_over_white, mode="RGB")
+    # img_np = _rgb_over_white
+    # --- end ORIGINAL ---
+
+    # --- NEW: alpha-aware RGB using median color along interior boundary as matte ---
     base_rgba = base_image.convert("RGBA")
-    _arr = np.array(base_rgba).astype(np.float32)
-    _rgb = _arr[..., :3]
-    _a = (_arr[..., 3:4] / 255.0)
-    _rgb_over_white = _rgb * _a + (1.0 - _a) * 255.0
-    _rgb_over_white = _rgb_over_white.astype(np.uint8)
-
-    img_pil = Image.fromarray(_rgb_over_white, mode="RGB")
-    img_np = _rgb_over_white
+    _arr = np.array(base_rgba).astype(np.float32)              # (H,W,4), RGB in 0..255, A in 0..255
+    _rgb = _arr[..., :3]                                       # (H,W,3)
+    _alpha8 = _arr[..., 3].astype(np.uint8)                    # (H,W) uint8 alpha
+    _a = (_alpha8.astype(np.float32) / 255.0)[..., None]       # (H,W,1) float alpha
+
+    # Build a foreground mask from alpha (slightly strict to avoid wispy edges)
+    _fg_mask = (_alpha8 > 128).astype(np.uint8) * 255          # (H,W) 0/255
+
+    # Morphological interior boundary: foreground minus a 1-iteration erosion
+    _k = np.ones((3, 3), np.uint8)
+    _eroded = cv2.erode(_fg_mask, _k, iterations=1)
+    _boundary = cv2.bitwise_and(_fg_mask, cv2.bitwise_not(_eroded))  # thin interior ring
+
+    # If boundary is too thin/few pixels, widen the ring via morphological gradient
+    if int((_boundary > 0).sum()) < 100:
+        _dil = cv2.dilate(_fg_mask, _k, iterations=2)
+        _ero = cv2.erode(_fg_mask, _k, iterations=2)
+        _boundary = cv2.subtract(_dil, _ero)
+
+    _idx = (_boundary > 0)
+    if not np.any(_idx):
+        # Fallback: use entire foreground if boundary not found
+        _idx = (_fg_mask > 0)
+
+    # Compute median color over the selected boundary pixels (in 0..255 space)
+    _median_color = np.median(_rgb[_idx], axis=0) if np.any(_idx) else np.array([255.0, 255.0, 255.0], dtype=np.float32)
+    _median_color = _median_color.reshape(1, 1, 3)             # (1,1,3)
+
+    # Composite RGB over median matte (avoid introducing black/white bias)
+    _rgb_over_matte = _rgb * _a + (1.0 - _a) * _median_color
+    _rgb_over_matte = np.clip(_rgb_over_matte, 0.0, 255.0).astype(np.uint8)
+
+    img_pil = Image.fromarray(_rgb_over_matte, mode="RGB")
+    img_np = _rgb_over_matte
     # --- end NEW ---
 
     # Prepare tensor