RewriteEngine On
RewriteBase /

# Skipped for existing images
RewriteCond "%{REQUEST_FILENAME}" "!-f"
RewriteCond $0#%{REQUEST_URI} ([^#]*)#(.*)\1$
RewriteRule "^([^/.]+)/([^/.]+).jpg$" "%2preview.php?t=$1&v=$2" [L,QSA]

RewriteRule "!^[^/.]+/[^/.]+.jpg|preview.php.*$" "-" [R=404,L,NC]