Php function to save a image - php

Question

I have some images used for the avatars of the users on my website, for example http://drksde.tk/images/avatar-Luxie.jpeg
I want to add a link that allow the users to download the avatar image, when someone click in the link a Save As dialog should appear.
Now the problem is that the picture is not downloaded properly, but the dialog appears, here is the link to download the avatar, and the code:
<?php
$username = $_GET['username'];
$size = $_GET['size'];
$ext = $_GET['ext'];
$border = $_GET['border'];
$basename = basename($_SERVER['REQUEST_URI']);
if(!isset($size)) { $size = 'small'; }
if(!isset($ext)) { $ext = 'jpeg'; }
if(!isset($border)) { $border = 'true'; }
$file = 'avatar-'.$size.'-'.$username.'.'.$ext;
header('Content-Description: File Transfer');
header('Content-Type: application/octet-stream');
header('Content-Disposition: attachment; filename='.$basename);
header('Content-Transfer-Encoding: binary');
header('Expires: 0');
header('Cache-Control: must-revalidate');
header('Pragma: public');
#header('Content-Length: ' . filesize($file));
ob_clean();
flush();
readfile($file);
exit;
?>

Answer 1

You can check out Example #1 in the php.net manual here:
http://php.net/manual/en/function.readfile.php
It shows how to force an image download.
You could place it into a script image.php and use it like this
download avatar image
You could use it with the $_GET['user'] parameter to serve the right user image file.
Just remember to validate the GET input.