[Xastir] DRG Error: Compression Algorithm Does Not Support Random Access

[ZPO]

Howdy!

I'm having an issue using the WA clipped DRGs from -
http://rocky2.ess.washington.edu/data/raster/drgclip/index.html - .

Some of the DRGs load fine, but the majority (especially the 24Ks)
give an error of "compression algorithm does not support random
access".  After some Googling, it appears this means the tiff files
were written in non-sequential format during the clipping process.  I
checked and it appears to be using PACKBITS compression and scanline
mode.

Based on my reading it appears the correct answer is to reprocess the
files through TIFFCP and convert them.  I'm unsure whether I should
convert them to strips or tiles.  It looks like scanline format is out
since it doesn't allow random access when using compression.  Between
strips and tiles, is there a preference on which Xastir can process
more efficiently for pan/zoom/update operations?  At first glance I'm
guessing tiles would be the most efficient.  Along with the goes the
question of recommended tile size.  16? 32? 64? 128?

I tried using TIFFCP on one file and it dumped the GEOTIFF-specific
tags as TIFFCP doesn't know what to do with them.
is there an analog to TIFFCP buried somewhere in the GEOTIFF tools
that I haven't found yet?  Fortunately, there are already TFW files
for each quad, but I'd like something a bit cleaner and standalone if
at all possible.  Once I've done a few more tests I can batch them up
and do them all at once.  Whatever method works best I'll post back to
the group.  Thanks in advance for any pointers and hints.

73 N5VFF - Brian