It seems that to convert Nikon Raw TIFF camera images (.nef anyone?) to anything other then that is to be done by a utility called ufraw, with help of another utility called dcraw. Luckily, both of these tools are already available in Fedora --as I expected.
Now, I do not know what these tools do or how they do what they do even though Lydia has tried to explain it to me. I think I have some sort of basic understanding but nothing more.
Lydia would like to be using the GIMP to convert her Forensic Science foo into very much different blabla once or twice or trice, all dependent on the ufraw plugin for the GIMP.
There we go, that's doable. I'll be working on that for her... During my vacation here ;-))
- ufraw plugin for the GIMP