FWIW, TIFF is an open specification,
http://partners.adobe.com/asn/developer/PDFS/TN/TIFF6.pdf
and *is* programatically accessable, I did it several years ago.
I have few complaints about either TIFF or HTML, however, for
best results I would choose PDF, I have seen many spectacular
renditions made with it. Just found the spec
http://partners.adobe.com/asn/developer/acrosdk/docs/filefmtspecs/PDFReferen
ce.pdf
John A.