Yes - the simplest way is just to use
Bitmap.GetPixel[
^]and
Bitmap.SetPixel[
^] - there are faster ways of doing the processing, but they require unsafe code and pointers, so I'd get it working with these first!
Do note that "white" is an ambiguous concept: it has a specific meaning in terms of bitmaps - full R, G, and B, basically - but as far as our eyes are concerned there are a range of RBG values which appear "white" or "off white". You may find there is very little actual "white" in a random image and need to provide a "whiteness" offset of some description.