I googled now about 30 min but I didn't find anything useful yet.
Anyone got a tutorial for that or is there a build in function in ASP.NET2?

I like to use a thumbnail function for my small gallery which resizes jpg gif png to a given size when the site is being displayed.

Thanks for every input!

Hello.

Several ones here:

http://www.google.pt/search?biw=1260&hl=pt-PT&q=generate+thumbnail+aspnet&meta=

Maybe this will help you:

http://www.developer.com/net/asp/article.php/3098311

One more page with example code

http://www.goucham.net/net/uploadimage.aspx