See the question and my original answer on StackOverflow

You can find a very good article from a Microsoft Employee here: Resizing images from the server using WPF/WIC instead of GDI+ that proposes to use WPF instead of GDI+. It's more about thumbnailing but it's overall the same issues.

Anyway, at the end it states this:

I contacted the WPF team to have the final word on whether this is supported. Unfortunately, it's not, and the documentation is being updated accordingly. I apologize about any confusion this may have caused. We're looking at ways to make that story more acceptable in the future.

So WPF is also unsupported in web apps and still is I believe :-S