PHP script to render a single transparent pixel (PNG or GIF)

I have to create a PHP that will return an image stream of one transparent dot (PNG or GIF)

Could you point me to an easy to use solution?

Answer

Transparent 1×1 PNG:

header('Content-Type: image/png');
echo base64_decode('iVBORw0KGgoAAAANSUhEUgAAAAEAAAABAQMAAAAl21bKAAAAA1BMVEUAAACnej3aAAAAAXRSTlMAQObYZgAAAApJREFUCNdjYAAAAAIAAeIhvDMAAAAASUVORK5CYII=');

Transparent 1×1 GIF:

header('Content-Type: image/gif');
echo base64_decode('R0lGODlhAQABAJAAAP8AAAAAACH5BAUQAAAALAAAAAABAAEAAAICBAEAOw==');