It looks very similar to a problem I had a while ago.
http://www.iceinspace.com.au/forum/a...tachmentid=557
Boiled it down to either a compression problem or electrical interference or too high gain (if bird says it I believe him
see
http://www.iceinspace.com.au/forum/s...light=jupiter). The image on the right is pre-waveletting in registax. You can already see the tesselation. The one on the right is after waveletting. Admittedly this is an extreme example, but some of the Unwaveletted images didn't show tesselation til after waveletting