Clean up image name after uploading

[Presto-X]

Hello everyone,

 

I want to clean up image names after they have been uploaded, I only want to use [a-z] and [0-9] and turn spaces in to underscores?

 

I was trying to use this but it took out the period before the image extension

 

$image = strtolower(preg_replace("/^[a-z0-9][a-z0-9\-]+[a-z0-9]$/i", "", $image));

 

These are some of the other ways I have tride, I think I am close just not quite there yet:

$targetChars = array(" ", "%20", "[", "]", "(", ")", "'", "-");
$image = str_replace($targetChars, "_", $image);
$image = preg_replace('/^\W+|\W+$/', '', $image);
$image = preg_replace('/\s+/', '_', $image);
$image = strtolower(preg_replace('/\W-/', '', $image));
$image = preg_replace('/[^a-z0-9]/', '', $image);
$image = strtolower(preg_replace("/^[a-z0-9][a-z0-9\-]+[a-z0-9]$/i", "", $image));
$image = preg_replace('/[^\w\d_ -]/si', '', $image);