Your picture is very unlikely to come back. ios devices have AES-256 encryption. Even if the file system data can still be dumped from the flash chip, it's easier to make up new photos than trying to crack it.
Erase all content and settings
The “Erase all content and settings” option in Settings obliterates all the keys in Effaceable Storage, rendering all user data on the device cryptographically inaccessible. Therefore, it’s an ideal way to be sure all personal information is removed from a device before giving
it to somebody else or returning it for service. Important: Do not use the “Erase all content and settings” option until the device has been backed up, as there is no way to recover the erased data.
From ios security overview