2007.01.04 18:56 "Re: [Tiff] Access to bare libtiff codecs?", by Edward Lam
approximate method you describe. At least, I don't know of any entirely in-memory TIFF-encode API functions. Of course, I'm no libtiff expert.
If you use the C++ interface, then in theory, you could create an in-memory TIFF file via TIFFStreamOpen() with a strstream.