How to make a thumbnail image of a pdf filedocument?

Hi guys,

I am wondering what the best practice is to show the pdf thumbnail of a pdf filedocument.

Should i make a thumbnail jpeg-image object of the pdf file document and show it on that way? Or should I store the PDF as an image object (seen it is a filedocument also) and then generate a jpeg-image of it?

Or how do you guys show it as thumbnail?

EDIT 1: we have different files in our app. we want to make an image of the pdf files we have in our app and show it to the user.

thnx