I have two questions.
1. There are four folders under images /library/. File, Flash, Image and Media. What are they?
2. I'm going to put the following .htaccess file inside images/ and above four folders, which could prevent file execution when someone somehow uploads a malware inside this public folder. Is this a good idea?
<FilesMatch "\.(php|pl|py|jsp|asp|htm|shtml|sh|cgi.+)$">
ForceType text/plain
</FilesMatch>
Also, I make sure 644 permissions for files and 755 permissions for folders.
I believe those directories are used by the file manager and one of the advance editors that uses a plugin for images. The only thing that should be in their are image files so your .htaccess file should be fine. Your permissions are fine as well.
Thanks.