Thinking about DNG
I guess I need to get out more…or I have too much time on my hands. Here I am, going through my image library, wondering what happened to my good intentions about using the DNG format for my stored RAW files.
Back in the summer of 2007 I jumped on the Lightroom train and made some significant improvements to the way I managed my image libraries. Nearly three years later I am working pretty much the same way…with a couple of exceptions.
The biggest thing I haven’t followed through with is the use of the DNG file format. On paper it really seems like a good idea. Especially for an information/data/asset management geek like myself. The three big positive features for me are:
1. Open file format – it doesn’t rely on any single company to ensure I will still be able to read my files in 20 years (anyone remember Kodak photocd format?)
2. No sidecar files – metadata is stored inside the DNG rather than in a separate file. Personally I think this is a good thing – one less file to delete by accident and a lot less files to backup.
3. File size – in general DNG files are smaller than the manufacturer’s proprietary formats (e.g. CR2 or NEF) due to a better compression algorithm. This is now becoming more important to me due to higher pixel counts and ever larger RAW files (my trusty old Canon 1D mkIIN RAW files are about 8mb, whereas my new Canon 7D files are about 24mb…).
So it seems that I really should make the change and start converting those files to DNG…
-!-
Lightroom, RAW, Technology
Reader Comments (6)
Hi Mark,
hope you enjoyed Mull (and judging by the pic of the "Flying Barn Doors" at the top of this posting, you did!)
I've bottled the "convert everything into DNG and throw away the CR2s" approach too - I'd had the same intention, with the added incentive that converted DNGs can allow you to process files from newer cameras in converters that might not have "caught up" yet.
I guess that - even though I've done a lot of comparative testing between DNGs and CR2s of the same images and have never been less than satisfied with the results of the converted DNGs - there's an attachment to the originals: I can't shake the notion that holding onto the CR2s is a good idea "just in case...", in which case there's no real point in DNGs for archiving...
And of course, storage is pretty cheap these days.
But I still like the *idea* of DNGs!
I look forward to following your progress towards this Brave New World..!
Dear Mark,
I have got an article and a video tutorial for you and your readers should you need more advice on the http://thelightroomlab.com/2009/06/converting-digital-camera-raw-files-to-the-dng-format-using-adobe-photoshop-lightroom/" rel="nofollow">three ways to re-wrap raw files into the dng container using Adobe Photoshop Lightroom. You can also find an excellent discussion of this file format's advantages http://www.dpbestflow.org/file-format/raw-file-formats" rel="nofollow">here from the ASMP's dpbestflow project.
--
David Marx
http://www.thelightroomlab.com
Thanks for that, David.
As it happens I'm happy using the Adobe DNG converter for the job - I'm not yet entirely immersed in Lightroom, being a big fan of Capture One, which plays very nicely with DNG files in my experience, and which (thanks to their recent acquisition of MS Expression Media, a free copy of which was made available to Cap One licence holders) also fulfills my DAM needs.
Thinking a bit more about this, one other thing that keeps me away from a fully DNG approach is that some converters - Bibble 5, say - don't support DNG at all.
If Bibble Labs ever get round to sorting their demosaicing algorithms out Lr 3-stylee, I'm quite likely to want to go back to it (it's currently great with some cameras like my 40D, but not remotely as good with others, like the 7D) and I won't be able to do that if I throw away all my CR2s.
Errrr... me again, Mark!
This time something very pro the DNG idea.
You know that I'm a big fan of the free Raw Therapee converter: unfortunately, the latest alpha release is unusably unstable on my machine, but the previous stable release doesn't support 7D files.
Last night I thought I'd see who RT would do with some "images I'd made" yesterday - just Blackbirds and the like in a local graveyard (trying - and failing - to find some Nigel Blake-style Spotflys!) - so I ran the files through the latest version (6.1) of the free DNG converter first (these are 400 ISO and 800 ISO files).
I've never noticed this before, but doing direct 100% crop comparisons of the CR2 and the DNG, the conversion to DNG has stripped out every last bit of Chroma noise from the image - they are literally squeaky clean, no observable Chroma whatsoever: there's a tiny - trivial - loss of micro contrast and very fine detail, and a tiny - trivial - colour shift, but overall the file is just much cleaner than the original, before any actual NR is applied.
I didn't have the chance to do any proper conversions though, so tonight I'm going to run a few DNGs and their equivalent CR2s through Lr 3 and Cap One 5 - I suspect that the conversions from the DNGs will be rather nice, and presumably even smoother and cleaner than the CR2 equivalents.
I've also just remembered that Cap One 5 can convert to DNG too (a direct conversion with no other changes applied) - it'll be interesting to see how those DNGs will look: and I might as well do likewise with Lr 3.
Have you noticed this "free" IQ benefit from converting to DNG, Mark? It does seem to change the nature of the OOF areas in other ways too - it slightly emphasises the slight maze effect that the green channel imbalance generates, but it smooths these artifacts out too, and I don't think they will be a problem at all in the end result.
I admit that I'm surprised by the extent to which the appearance of the file changes when converted to DNG - as I say I've never been conscious of this before (and I'm pretty sure I'd have done like-for-like comparisons in the past on say, 40D files) and the changes, although arguably welcome, aren't exactly trivial or insignificant..!
Thanks David and Keith.
Keith, interesting stuff - look forward to hearing the results of your tests.
In the run-up to switching to DNG, I completed the first stage of my workflow changestoday - I have finally got all my images into a single LR3 catalog. I had been using multiple catalogs (e.g. one for avian, one for other nature, one per client etc.) bit decided to use LR3 as the catalyst for change.
Next step is to get my CR2s converted to DNG...then find time to finish the updates to all my plug-ins...