2004.03.19 04:05 "Re: [Tiff] TIFF to BMP or similar", by Bob Friesenhahn
You will obtain the best leverage to accomplish this if you start with software that can already do what you say. See ImageMagick (http://www.imagemagick.org) or GraphicsMagick (http://www.graphicsmagick.org/) for packages that can already read and write TIFF and BMP, plus output data in the format you specify.
The main holdup will likely be the use of Watcom C/C++ since ImageMagick works with the Microsoft compiler, and GraphicsMagick works with the Microsoft and Borland compilers. Some effort would be required to use a different compiler.