Scan only what's inside the scanning rectangle

[matteoberla]

Hi,
i've noticed that the package doesn't scan only what's inside the scanning rectangle,
but when i have a page with many barcodes i don't know whick one is chosen and makes it difficult to use it as i need to cover the ones i don't need to scan.

Is it possible to force the package to scan only on the scanning area? Thnak you.