I know pngcrush, optiPNG and so on, but all of them are just a command line tools. What I need is a dll that I could use internally in my application. It's hard to believe that there is no such thing... yet I couldn't find one.

To make things clear: I need that for 32bit ARGB images, so conversion to 8bit is not an option. I need real optimization.

I would like to use the library within .net app, but I can do P\Invoke, so managed code is not necessary.