To DNG or not

[Curtis Cunningham]

The posts I've searched through on DNG files are all about a year old, and so I thought I'd see what the current thinking is on this format.

I'm just starting out with understanding RAW files and am reading Bruce Fraser's book on Camera RAW for CS2. He makes what seems to me to be a strong case for using DNG files. While he admits his bias in this area, I'd like to know what you all think about this format to help me understand it a little better.

Thanks.

[Dennis_Vied]

I have not yet had the opportunity to use DNG. A couple of years ago, it was a hot item when Open RAW was making the very valid argument that the community must have a format that would survive all the changes in software and hardware. It seems to have died down now, but nevertheless is still a very valid argument.

My gut hunch is, as long as good support for all RAW files exist, DNG will never grab a toehold.

[DierkHaasis]

Still the same as a year ago:

If you have or plan an Adobe centric to exclusive work-flow DNG is the way to go. That means Lightroom->Bridge->Photoshop->Lightroom. I am sure you are experienced enough to save and back-up your original camera RAW files.

If you rely on non-Adobe products for image handling and processing DNG is just another format, one that isn't widely adopted or supported. It might still make sense to use DNG in this case if you have a camera producing sidecar files with your RAW photo, since DNG merges them into one file easier to handle. Unfortunately you might then have to convert to TIFF before using other programs.

For example, I use Nikon cameras and NEF. Over the course of Nikon Capture NX's lifetime I have come to like this program a lot and rely on it. ATM Capture NX supports only [camera] NEF, TIFF and JPEG but can save all three as NEF. For some years I also had a Canon G2, which produces CRW+THM, the latter of which contains the preview and metadata; I converted them to DNG for easier handling, then converted those with standard settings to TIFF, opened the TIFF in NX, worked on the photo and saved it back as NEF. Not the best of work-flows.

[AndrewRodney]

Convert to DNG is my first step in ingestion. It will verify the Raw so I know the data is fine before I format the card.

I don't like sidecar files, I want the rendering instructions inside the DNG. DNG's without also embedding the original Raw (so you CAN get that NEF out should you wish) is smaller than original Raw file.

DNG contains embedded JPEG of a size you can specify, can update based on current rendering instructions, can be used for printing without rendering the entire DNG (we need applications to support this).

Non proprietary format. Not held hostage by Canon or Nikon. DNG is an open spec.

[Noel_Carboni]

Perhaps, but you can be sure the ability to open older proprietary .CRW or .CR2 (or .TIFF or .NEF) raw files will remain available for a long time.

Adding a step to change the format on general principles costs time and effort.

Direct storage of the parameters used to convert/manipulate the file is nice, but practically speaking there are new conversion and editing features being added all the time, so if you need to revisit an old raw file you might want to forget the old choices and do it all over again anyway.

For what I do I find I don't normally have to go back and revisit large groups of conversions, but rather I go back and do individual conversions. An example was a landscape shot I wanted to reprint not long ago... When I did the first edit of the image years ago I saved the result as a .psd, from which I did prints. I was always bothered a little by some minor color fringing the lens delivered at the corners. Back when I first did the conversion there was no CA correction capability. Now there is. So when I reworked the image I was able to employ the more modern Camera Raw converter and I got a better result, not to mention the slightly different choices I made during editing because I'm better at it now than I was then. Would DNG have helped me here? Not really.

I guess it boils down to whether you feel ongoing extra effort is warranted to buy you some theoretical non-proprietary format compatibility and long-term storage of your conversion and editing parameters.

-Noel

[AndrewRodney]

Originally Posted by Noel_Carboni

Perhaps, but you can be sure the ability to open older proprietary .CRW or .CR2 (or .TIFF or .NEF) raw files will remain available for a long time.

I don't know how long, a long time is.

Back in the 1990's, I thought I'd be able to open (acquire) my PhotoCD image packs. Now I can't in CS3/Mac Intel without jumping through hoops. Eventually? Who knows.

Adding a step to change the format on general principles costs time and effort.

It takes a bit more time to ingest when I import into Lightroom but I have verified all the data before card format. The only other way to do this would be not to import DNG, ask for 1:1 previews which actually take longer and more disk space.

Direct storage of the parameters used to convert/manipulate the file is nice, but practically speaking there are new conversion and editing features being added all the time, so if you need to revisit an old raw file you might want to forget the old choices and do it all over again anyway.

I don't want to risk losing any of the original rendering instructions with double the number of files I'd have to keep track of. I do like having a smaller Raw archive. I expect to see some really useful capabilities embedded in DNG in the future that will not be possible in a Raw, like multiple rendering instructions. Or a print history etc. DNG is like PDF for Raws.

Of course, you don't have to use it. There are enough compelling advantages to me that I do.

[Noel_Carboni]

I imagine that if/when the ability for me to open my D30 .CRW files goes away, that I'll just convert them to JPEG or TIFF with the older version of Photoshop that I will still have installed.

Is .DNG evolving? Will programs always be able to open early "versions" of .DNG? Is there any certainty that .DNG support will be around longer than .CRW support?

Trying to illuminate the compelling reasons for using .DNG is exactly why we're discussing this. Thank you for your insights, Andrew and everyone.

Just curious: How often do you detect a corrupted raw file, Andrew? Can't say I've ever run across a bad one myself. I guess it's always a good thing to verify your files, but if a file IS corrupted, what can you do about it? Are you suspicious of your CF cards, computer hardware, cabling, what? A little more money invested in top quality hardware could help there rather than taking on additional work for every photo.

I don't want to risk losing any of the original rendering instructions

I guess that's the fundamental point where you and I differ... But of course as I described I simply don't find the need to go back to a whole mass of edited files very often, and when I do I actually quite enjoy reprocessing the data from the original raw file(s). By the way, a sidecar file doesn't have to be generated; I don't like 'em either, and prefer to have the converter remember the conversion parameters in its central database. Again, this speaks to my not having a lot of love for the conversion process nor the parameters I've selected; as far as I'm concerned raw conversion is just a necessary evil to get me to where I can *really* edit an image. I suppose I'm just an outdated old timer for thinking like this.

-Noel