This is a bit of a tech topic, but so far I can’t find an authoritative answer to it. It would seem, from my experience of recently upgrading from Lr 2.6 to Lr 2.7, and also from testing the 30-day trial of the Lr 3.0 release, that there is some confusion (at least in my mind) over the new raw pipeline shared with ACR and exactly what it does or does not do.
I think this may be partly due to the fact that 2.7 kind of slipped by pretty much under the radar without much comment here, because everyone had their attention on the imminent release of Lr 3. Anyhow, it would seem that 2.7 has exactly the same new demosaicing algorithm as Lr 3, but without the remainder of the the PV 2010 raw pipeline. There is no mention of this in the release notes pdf for 2.7, in fact I discovered it quite by chance when browsing Victoria Bampton’s site. So 2.7 is actually rather more than just a dot upgrade with support for a few new cameras. But there seems to be even more to it than this.
Last night I thought I would compare TIFFs which I had exported in Lr 2.6 with the same image RAW files in 2.7, which have exactly the same develop settings as when they were exported. I wanted to see if the demosaicing was really much different, and what exact effect that might have. I did this by printing an enlarged crop from each file of the same image area, to the same degree of enlargement.
There was a noticeable and quite unexpected difference. The RAW image in 2.7 has a lot more noise in the shadow areas than the file I produced in 2.6. The correctly exposed areas also have a very slightly better rendering of fine detail. But it looks as if 2.7 applies considerably less noise reduction by default than 2.6, which means that all the images I previously edited before upgrading will need re-visiting with new NR edits (if I want to print from the RAW rather than the TIFF). Again, I see no mention of this in the 2.7 release notes.
Would anyone care to comment, or would other 2.7 users like to check their files?
John