<?php
// hemiolos.lima-city.de/forum/image_test.php

echo "<img src=\"./image.php\" alt=\"--\" />";

// source output
echo '<hr />';
highlight_file('./image_test.php');
echo '<hr />';
highlight_file('./image.php');

<?php
// hemiolos.lima-city.de/forum/image.php

$bild = './test.png';

$im = imagecreatefrompng($bild);

header('Content-type: image/png');

imagepng($im);
imagedestroy($im);