If you drag an object outline,you can easily delete the background by deleting the rest.
Subsequent modifications are easily calibrated with area fill or area delete functions.

It is inconvenient to delete existing backgrounds and delete all background areas with the delete tool.
This app has the advantage of being able to reveal exactly what you want,just like a lasso.

[main function]
 - Area lasso (background can be removed with one drag)
 - Fill area
 - Delete area