Update app.py

app.py

@@ -32,7 +32,7 @@ def warp_design(design, mask, warp_scale):
     scaled_mask = (mask * 255 * (warp_scale / 100)).astype(np.uint8)
     
     # Ensure mask is single-channel
-    if len(scaled_mask.shape) == 3:
+    if len(scaled_mask.shape) == 3 and scaled_mask.shape[2] == 3:
         scaled_mask = cv2.cvtColor(scaled_mask, cv2.COLOR_BGR2GRAY)
 
     return cv2.bitwise_and(design_resized, design_resized, mask=scaled_mask)