gistfile1.txt

db.tickets.find({'contact.portrait': {$exists: true}}).snapshot().forEach(
	function (ticket) {
		var rfc2397_portrait = 'data:' + ticket.contact.portrait['mime-type'] + ";base64," + ticket.contact.portrait.data.base64();
		db.tickets.update({_id: ticket._id},
			{
				$set: {
					'contact.rfc2397_portrait': rfc2397_portrait,
				},
				$unset: {
					'contact.portrait': true,
				},
			}
		);
	}
);