You would have to access the backup files. Where ever they were stored. If the files were only on the phone itself, then you would have to copy them to an account (google, cloud, etc.) or to a computer and then copy them over to the tablet. You could also reinstall that account to the phone (you can have more than one) and then sync those images (if on the phone) to the account. Download them on the tablet and then again remove the account.