I'm executing dcraw and using an anonymous pipe to pipe it to a char array.
My question is how can I create a
You can create a Gdiplus::Bitmap from an IStream source. There are built-in Windows APIs that can do this for you - see CreateStreamOnHGlobal. Another way is to write your own class that implements IStream.
Here is an example using CreateStreamOnHGlobal to load PNG resources from memory.