RewriteEngine on
RewriteCond %{HTTP_REFERER} !^http://(www\.)?images.yandy.com(/)?.*$     [NC]
RewriteCond %{HTTP_REFERER} !^http://(www\.)?yandy.com(/)?.*$     [NC]
RewriteCond %{HTTP_REFERER} !^https://(www\.)?yandy.com(/)?.*$     [NC]
RewriteRule ^(.*)(gif|jpg|jpeg|bmp|png)$ - [F,NC]