($width, $height) = $im->getBounds();

##</code><code>##

$centerX = $width / 2;
$centerY = $height / 2;

##</code><code>##

$black      = $im->colorAllocate(0,0,0); 
$font_file  = gdGiantFont;
$text       = "test";

$im->string($font_file, 400, 240, $text, $black);