tiff or tif is actually the preferred bitmap for most professional graphics.probably the best available for OS/2 albeit using x11 are Imagemagick or Gimp
OpenOffice.org and even the old StarOffice SHOULD be able to handle most *.tiff files as will older winOS/2 (win16)versions of Corel Photo Paint Adobe Illustrator etc,
tiffs are non lossy and as such are larger and require more memory than the compressed bitmaps.
You could convert but for maintaining qaulity it is best to keep the file as tif for quality, you can always convert to jpeg png etc later for individual uses of the file