Recently we have found TIFF manipulation packages which do not recognize
TIFF files output by xv.  This is due to a missing XRESOLUTION and YRESOLUTION
tag which apparently is required (or at least believed to be required) for
valid TIFF.  I have checked both xv 2.x and xv 3.x and neither of these
do indeed copy these tags.

Has anyone out there hacked in the fixes for xv to support these tags?
I have been told that I could find some code in tiff/tools/tiffcp.c, but
that directory is one of many of the tiff group not distributed with xv.  I
hope to obtain the original tiff src and look at it, but would prefer
to find code already known to work in xv.