Make php echo a 1x1 transparent gif in a few different ways

pxl-char.php

header( 'Content-type: image/gif' );
# The transparent, beacon image
echo chr(71).chr(73).chr(70).chr(56).chr(57).chr(97).
     chr(1).chr(0).chr(1).chr(0).chr(128).chr(0).
     chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).chr(0).
     chr(33).chr(249).chr(4).chr(1).chr(0).chr(0).
     chr(0).chr(0).chr(44).chr(0).chr(0).chr(0).chr(0).
     chr(1).chr(0).chr(1).chr(0).chr(0).chr(2).chr(2).
     chr(68).chr(1).chr(0).chr(59);

pxl-fwrite.php

header("Content-type: image/gif");
		header("Content-length: 43");
		$fp = fopen("php://output","wb");
		fwrite($fp,"GIF89a\x01\x00\x01\x00\x80\x00\x00\xFF\xFF",15);
		fwrite($fp,"\xFF\x00\x00\x00\x21\xF9\x04\x01\x00\x00\x00\x00",12);
		fwrite($fp,"\x2C\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02",12);
		fwrite($fp,"\x44\x01\x00\x3B",4);
		fclose($fp);

pxl-pack.php

header("Content-Type: image/gif");
header("Content-Length: 49");
echo pack('H*',
  '47494638396101000100910000000000ffffffff'
 .'ffff00000021f90405140002002c000000000100'
 .'01000002025401003b'
);