How to replace or rename image file name containing umluats or accents on file upload

Hello, as I am based in Europe I have a problem that people using our website and wishing to upload an image often have an umlaut, an accent or an empty space in their image file name such as: märz.jpg or le hôtel.jpg.

While the file will upload and the name will be inserted into the DB, the image will not display due to this problem.

In another thread I am asking about how to rename both the uploaded file and the text that is inserted into the DB with a number.

Another approach would be to remove the offending characters as discussed in the thread (Rejecting File Names with Wrong Characters - 11/26/2012) where Jason Byrnes wrote:

the following example will remove the & \ ' character, you can add others to the array:
<?php
if(isset($_FILES)) {
foreach($_FILES as $k => $v) {
$_FILES[$k]["name"] = str_replace(array("&","\\","'"),"",$_FILES[$k]["name"]);
}
}
?>

----------------

Taking this approach I have added the following code to the top of mage page:

----------
<?php
if(isset($_FILES)) {
foreach($_FILES as $k => $v) {
$_FILES[$k]["exhibition_image"] = str_replace(array("ä","ö","ü","é","à","é","ò","ô"," ","&","\\","'"),"",$_FILES[$k]["exhibition_image"]);
}
}
?>

------------
From the upload form:

<input name="exhibition_image" type="file" id="exhibition_image">

----------

From the upload Server behavior:

$InsertQuery->bindColumn("exhibition_image", "s", "".((isset($_FILES["exhibition_image"]))?$_FILES["exhibition_image"]["name"]:"") ."", "WA_DEFAULT");

---------

Unfortunately, both the uploaded image file as well as the file name text inserted into the DB still have the umlaut.

I am using the WA MySqli extension and WA DataBridge File Manipulation feature.

Any suggestions?
Thanks for your help.