To set up and output an image the very minimum:
<?php
$img = new Imagick();
$img->newImage( 200, 200, new ImagickPixel( 'lime' ) );
$img->setImageFormat( "png" );
header( "Content-Type: image/png" );
echo $img;
?>
Copy, paste; and if imagemagick is enabled it should come up with a lime colored square.