>Hi, > >today's compression technology is serious science indeed. Yes, >the lossless compression in NEF is only almost lossless. I >tested the compression performance in my D3 and the file size >dropped from 25 MB to 15 MB. I use it all the time.
This is a real surprise to me, so I just went and read hundreds of postings over the years, and I could not find anything really definitive. Some seemed to mix up early compressed (no adjective) with the newer lossy vs. lossless compressed.
Some did it by testing -- taking two images and comparing -- and for the kind of extremely slight variations attributed to lossless loss, I can't see that as ever really working.
The most interesting were discussions of the actual code to de-compress, but that all seemed also to date back to D70 days?
Nikon calls its algorithm "reversible". Generally speaking, unless it lost something in translation, that would imply no loss at all.
Are you SURE that Lossless truly has loss? Has Nikon ever commented?