* remember not to delete anything until right at the end (in case GPX waypoint
  refers to a pic that's the first in a batch, the later ones of which we want
  to keep)

* strip orientation information and embedded thumbnails:

      	exiftool -overwrite_original -n -Orientation=1 *.JPG *.jpg
	exiftool -overwrite_original -ThumbnailImage= *.JPG *.jpg

  (this will leave creation data the same)

* flush all thumbnail caches with:

	killall thunar Thunar
  	rm -fr ~/.cache/thumbnails/ ~/.cache/geeqie/thumbnails
	thunar &
	
* move pictures to top/bottom/left/right subdirs as usual but copy back with:

  	mkdir bottom left right top
      	for X in bottom/*; do jpegtran -copy all -rotate 180 $X > ${X#*/}; done
      	for X in left/*; do jpegtran -copy all -rotate 90 $X > ${X#*/}; done
      	for X in right/*; do jpegtran -copy all -rotate 270 $X > ${X#*/}; done
      	mv top/* .
      	rm -fr bottom left right top

   (ignore 'Invalid SOS parameters for sequential JPEG' errors)

* use prefix-createdate to create a symlink farm of the picture files with the
  recorded (and possibly wrong) creation time at the front so they get sorted
  on that attribute

* if times of the camera photos need shift w.r.t. phone photos then use something
  like:
  
	exiftool -overwrite_original -createdate+=36 SAM_*

  (adds 36 hours to create timestamp; don't know how to do minutes; refer to man
  page)

  and then regenerate the symlinks with prefix-createdate again

* run the pic renamer