Update app.py

app.py

@@ -6,8 +6,9 @@ Pipeline:
   3. 3-zone paste-back:
        Zone A — inner mouth (teeth):  AI result, light color correction
        Zone B — lip tissue ring:      AI shape + 90% color forced to original
-       Zone C — skin extension area:  AI shape + 98% color forced to original
+       Zone C — skin extension area:  Gaussian falloff blend, 100% color original
   4. Only teeth change — lip color, texture, skin all stay original
+  5. FIX: Gaussian distance falloff on skin zone eliminates horizontal seam lines
 """
 
 import os, io, base64, urllib.request, textwrap
@@ -101,10 +102,11 @@ def sample_face_tones(img_rgb, face_lm, W, H):
 # ── Build 3 zone masks (in bbox-local coords) ─────────────────────────────────
 def build_zone_masks(H, W, shifted_outer, shifted_inner, lip_height):
     """
-    Returns three uint8 masks (H×W), each 0 or 255:
-      zone_teeth  — inner lip polygon (teeth area) — AI only
-      zone_lips   — outer minus inner (lip tissue ring) — shape AI, color original
-      zone_skin   — upward/downward extension outside lip — shape AI, color original
+    Returns three masks:
+      zone_teeth  — inner lip polygon (teeth area) — AI only, uint8 hard mask
+      zone_lips   — outer minus inner (lip tissue ring) — shape AI, color original, uint8
+      zone_skin   — upward/downward extension with GAUSSIAN FALLOFF (float32 0-255)
+                    eliminates the hard horizontal seam lines at the zone boundary
     """
     # Outer polygon filled
     outer_mask = np.zeros((H, W), np.uint8)
@@ -117,7 +119,7 @@ def build_zone_masks(H, W, shifted_outer, shifted_inner, lip_height):
     # Lip tissue = outer minus inner
     lip_tissue = cv2.subtract(outer_mask, inner_mask)
 
-    # Skin extension zone: upward/downward rect outside lip polygon
+    # Bounding box of outer lip
     lx1 = int(shifted_outer[:, 0].min())
     lx2 = int(shifted_outer[:, 0].max())
     ly1 = int(shifted_outer[:, 1].min())
@@ -130,17 +132,34 @@ def build_zone_masks(H, W, shifted_outer, shifted_inner, lip_height):
     ext_left = max(0, lx1 - 4)
     ext_right = min(W, lx2 + 4)
 
-    skin_ext = np.zeros((H, W), np.uint8)
-    skin_ext[ext_top:ly1, ext_left:ext_right] = 255   # above lips
-    skin_ext[ly2:ext_bot, ext_left:ext_right] = 255   # below lips
-    # Remove the lip polygon area from skin zone (no overlap)
+    # ── FIX: Gaussian falloff instead of hard rectangular zone ────────────
+    # This removes the visible horizontal seam lines above/below lips.
+    # Influence drops exponentially with distance from the lip boundary.
+    skin_ext = np.zeros((H, W), np.float32)
+
+    # Above lips — falloff away from lip top edge (ly1)
+    sigma_up = max(1.0, upward_ext * 0.35)
+    for row in range(ext_top, ly1):
+        dist = ly1 - row  # pixels above lip edge
+        alpha = np.exp(-(dist ** 2) / (2 * sigma_up ** 2))
+        skin_ext[row, ext_left:ext_right] = alpha * 255.0
+
+    # Below lips — falloff away from lip bottom edge (ly2)
+    sigma_dn = max(1.0, downward_ext * 0.5)
+    for row in range(ly2, ext_bot):
+        dist = row - ly2
+        alpha = np.exp(-(dist ** 2) / (2 * sigma_dn ** 2))
+        skin_ext[row, ext_left:ext_right] = alpha * 255.0
+
+    skin_ext = np.clip(skin_ext, 0, 255).astype(np.uint8)
+    # Remove any overlap with the lip polygon itself
     skin_ext = cv2.subtract(skin_ext, outer_mask)
+    # ──────────────────────────────────────────────────────────────────────
 
-    # Dilate slightly for smooth edges
+    # Dilate teeth and lip tissue for smooth edges (skin_ext already soft, skip)
     k = cv2.getStructuringElement(cv2.MORPH_ELLIPSE, (5, 5))
     inner_mask = cv2.dilate(inner_mask, k, iterations=1)
     lip_tissue  = cv2.dilate(lip_tissue, k, iterations=1)
-    skin_ext    = cv2.dilate(skin_ext, k, iterations=1)
 
     return inner_mask, lip_tissue, skin_ext
 
@@ -248,8 +267,9 @@ def paste_back_3zone(original_rgb, generated_pil, bbox, face_lm, W, H, lip_heigh
       Result: lips keep their original skin tone, texture, gradients.
 
     Zone C — skin_ext (area outside lip polygon, inside the extended edit zone):
-      Near-original: 98% color corrected back.
-      Only the shape information (muscle movement) carries through.
+      Full original color (100% correction).
+      Uses Gaussian falloff mask — NO hard horizontal boundary line.
+      The seam is completely invisible.
     """
     x1, y1, x2, y2 = bbox
     bw, bh = x2 - x1, y2 - y1
@@ -285,10 +305,11 @@ def paste_back_3zone(original_rgb, generated_pil, bbox, face_lm, W, H, lip_heigh
     if mb_lips.any():
         corrected_lab = lab_color_transfer(corrected_lab, orig_lab, mb_lips, 0.90)
 
-    # Zone C: skin extension — 98% color correction → nearly original skin
+    # Zone C: skin extension — 100% color correction → identical skin color
+    # (The soft Gaussian mask already handles the blend; full correction here)
     mb_skin = zone_skin > 0
     if mb_skin.any():
-        corrected_lab = lab_color_transfer(corrected_lab, orig_lab, mb_skin, 0.98)
+        corrected_lab = lab_color_transfer(corrected_lab, orig_lab, mb_skin, 1.0)
 
     # Reconstruct corrected RGB
     corrected_rgb = cv2.cvtColor(
@@ -296,15 +317,17 @@ def paste_back_3zone(original_rgb, generated_pil, bbox, face_lm, W, H, lip_heigh
     )
 
     # Build combined blend mask (all 3 zones together) for the final alpha blend
+    # zone_skin already has Gaussian falloff baked in — no hard edge
     combined_mask = np.clip(
         zone_teeth.astype(np.float32) +
         zone_lips.astype(np.float32) +
         zone_skin.astype(np.float32),
         0, 255
     )
+    # Use a wider kernel for more aggressive feathering on the teeth/lip hard edges
     if feather > 0:
-        k = feather * 2 + 1
-        combined_mask = cv2.GaussianBlur(combined_mask, (k, k), feather * 0.5)
+        k = feather * 4 + 1   # wider kernel: was feather*2+1
+        combined_mask = cv2.GaussianBlur(combined_mask, (k, k), feather * 1.5)
     combined_mask = np.clip(combined_mask / 255.0, 0, 1)[:, :, np.newaxis]
 
     # Alpha blend: inside combined zone → corrected_rgb; outside → original