Password protect large file

I've noticed that in some galleries, folks have been able to password protect the links to the cel page, while still displaying a thumbnail for the cel. How can I do this? I want people to be able to see a censored thumbnail, but still need a password to view the uncensored file.

Go to "My Account," then under "Style," click on "Gallery Settings" and choose yes for password protect.

I don't think there's a way to set this up for individual cels--it's all or nothing. Unless, of course, you want to completely protect the cel, thumbnail and all. That can be done by editing the cel.

Thank you, klet! That is exactly what I was looking for. Much appreciated.