This is a bug fix for alpha channel blending as submitted by Jan.

WriteableBitmap in Sivlerlight uses pre-multiplied values for the colors when there is transparency involved (see MSDN Article), so PNGWriter must de-multiply the values.  unfortunately this is not a lossless process so the colors will be a little bit off, but it should not be noticeable to end users.

Thanks Jan!

I’ve released two libraries for Windows Phone, one is a CRC library, supporting both CRC32 and Adler32 CRC functions, the other is and PNG writer for WriteableBitmaps.

Both of these libraries are eventually going to be used in Live Titles to support transparency but aren’t quite ready for prime time yet.

Both libraries are released to the public domain.