add default alpha_matting

app.py

@@ -28,6 +28,15 @@ def remove_background(input_image, bg_color, model_name, alpha_matting, post_pro
             "post_process_mask": post_process_mask,
             "only_mask": only_mask
         }
+
+        # Add alpha matting parameters if enabled
+        if alpha_matting:
+            remove_kwargs.update({
+                "alpha_matting": True,
+                "alpha_matting_foreground_threshold": 270,
+                "alpha_matting_background_threshold": 20,
+                "alpha_matting_erode_size": 11
+            })
         
         # Use the remove function
         if session or bg_color_rgba: