Whether this is worthwhile is debatable since here we are not transmitting data over a network
In addition, jpeg2000 (the biggest data hog) is already a compressed image format.
May not remain.
This is an extremely crude implemenation which almost works by accident. Nevertheless it does work.
It can be tested with the instructions at http://opensimulator.org/wiki/Feature_Proposals/Deduplicating_Asset_Service#Testing
It does not interact at all with the existing asset service or any data stored there.
This code is subject to change without notice and should not be used for anything other than gawking.