透過1px×1pxのGIFをPHPで出力

メモ。

<?php
header('Content-Type: image/gif');
echo base64_decode('R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==');

ちなみにPNGの場合。

<?php
header('Content-Type: image/png');
echo base64_decode('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAABGdBTUEAAK/INwWK6QAAAAtJREFUGFdj+A8EAAn7A/0r1QhFAAAAAElFTkSuQmCC');