the answer, if ever, is in the man page of mkisofs, because growisofs forwards
the arguments about content to this program.
The newer releases of cdrtools support an option -find
with mkisofs. See
http://cdrtools.sourceforge.net/private/man/cdrecord/mkisofs.8.html
After reading the description of -find, examples, and dead link, i would try
growisofs -Z /dev/dvdrw -R -J -find /some/files -name '*.jpg'
In practice i don't try this, because i have my own program
xorriso for such jobs. :))
xorriso -outdev /dev/dvdrw -blank as_needed -joliet on \
-findx /some/files -name '*.jpg' -exec add_missing / --
This will copy the *.jpg files underneath /some/files into
the ISO and create the directories which host them.
E.g. file /some/files/dogs/wuffy.jpg will become /dogs/wuffy.jpg in the ISO.
Have a nice day :)
Thomas