how to clean whiteboard snapshots in general:

  http://matthew.mceachen.us/blog/how-to-clean-up-photos-of-whiteboards-with-gimp-403.html
  apparently the URL above is defunct.

  new URL on this topic: https://gist.github.com/adsr303/74b044534914cc9b3345920e8b8234f4
  requires a bit of gimp knowledge.

====

[untested]

script for whiteboard cleaning in batch can be found in this folder also.
the batch-whiteboard-clean.scm script should go in: ~/.gimp-2.6/scripts
command:
  gimp -i -b '(batch-whiteboard-clean "*.png")' -b '(gimp-quit 0)'
from site: http://registry.gimp.org/node/19822