Update app.py

app.py

@@ -40,10 +40,9 @@ def warp_design(design, mask, warp_scale):
     # Resize design to match mask dimensions
     design_resized = cv2.resize(design, (w, h))
 
-    # Ensure mask is single-channel grayscale
-    if len(mask.shape) == 3:
+    if len(mask.shape) == 3 and mask.shape[2] == 3:
         mask = cv2.cvtColor(mask, cv2.COLOR_BGR2GRAY)
-    
+
     # Ensure mask is uint8
     if mask.dtype != np.uint8:
         mask = (mask * 255).astype(np.uint8)