David Anson wrote his own PNG encoder and shares with you the source code, a simple test application and the automated test suite.
Source: Delay's Blog
Okay, so what does a PNG (Portable Network Graphics) image encoder have to do with pseudo-localizing on the Silverlight platform? Almost nothing - except for the fact that I went above and beyond with my last post and showed how to pseudo-localize not just text, but images as well. It turns out the technique I used for that (reading the System.Drawing.Image instance from the resources class and manipulating its pixels before handing it off to the application) won't work on Silverlight.