Can I "echo" a .jpg image through php without processing it?

Yes, you can. Just readfile instead of imagecreatefromXXX+imagejpeg.

header('Content-Type: image/jpeg');$src = /* process $_GET['image'] to recover the path */;readfile($src);

The /* process $_GET['images'] to recover the path */ part implies any sanitizing you need to do on the input to avoid that someone requests a forbidden file. If your script input is a file path, this may mean checking from a predefined list, stripping of possible directory separators, checking against a regex, etc. Another way would be to store paths inside a database and pass the script a simple id, and recover the file path with it. This might be a better idea, as users will see no mention of any file path on the script URL (if you just pass a path, people can actually guess where files are, and that's what you're trying to prevent).

Sure, using readfile. Don't forget to restrict the allowed image names. Otherwise, you'd be creating a directory traversal vulnerability.

header('content-type: image/jpeg');$img = preg_replace('/[^0-9a-z\._\-]/', '_', $_GET['image']);readfile($img);

What about something like http://www.php.net/manual/en/function.readfile.php

From the example

<?php$file = 'monkey.gif';if (file_exists($file)) {    header('Content-Description: File Transfer');    header('Content-Type: application/octet-stream');    header('Content-Disposition: attachment; filename='.basename($file));    header('Content-Transfer-Encoding: binary');    header('Expires: 0');    header('Cache-Control: must-revalidate, post-check=0, pre-check=0');    header('Pragma: public');    header('Content-Length: ' . filesize($file));    ob_clean();    flush();    readfile($file);    exit;}?>