phpthumb - disable output - php

Question

$phpThumb->GenerateThumbnail() or $phpThumb->RenderToFile() create a output with header information and the thumbnail. How can i disable it? I need to store the thumbnail without a return of the thumbnail on the harddisk.
Here is my code:
require 'class.phpthumb/phpthumb.class.php';
$phpThumb = new phpThumb();
$phpThumb->config_temp_directory = 'thumbnails_c/';
$phpThumb->config_cache_directory = 'thumbnails_c/';
$phpThumb->config_cache_disable_warning = true;
$phpThumb->cache_maxage = 86400 * 30;
$phpThumb->cache_maxsize = 10 * 1024 * 1024;
$phpThumb->config_cache_force_passthru = false;
$phpThumb->setSourceData($file_data);
$phpThumb->setParameter('w', 45);
$phpThumb->setParameter('h', 32);
$phpThumb->setParameter('zc', 1);
$phpThumb->setParameter('JPEGquality', 100);
$phpThumb->setParameter('f', 'jpeg');
if ($phpThumb->GenerateThumbnail()) {
if ($phpThumb->RenderToFile($path_to_the_new_file)) {
// return the data as an array
return array(
'thumbnail' => $phpThumb->OutputThumbnail(),
'contenttype' => 'image/jpeg',
);
} else {
// error
return false;
}
} else {
// error
return false;
}
greetings!

Answer 1

From the readme:
Calling as an object (not using phpThumb.php):
NOTE: most people don't need to and
should not do this. If you just want
to display resized images, please just
use phpThumb.php, not the object mode.
To render output to one (or more)
files instead of the browser, you
should skip phpThumb.php and
instantiate your own object.
Please take a look at
/demo/phpThumb.demo.object.php for
details.