In the workflow class I taught last weekend, we had some discussion about the Adobe DNG format, and if RAW shooters should convert to DNG when uploading their images to the computer.
I've published a fair amount on this subject. In Digital Photography Podcast 114, Julieanne Kost talks about on Lightroom and DNG, and she's a big proponent of the open file format. Anyone who has been to one of my workshops knows that if you're not using Lightroom or Aperture, I recommend Photo Downloader, which comes with Adobe Bridge and allows you to convert to DNG during the upload process (as does Lightroom).
But, just because you can convert to DNG easily, does that mean you should? I'm not as worried about my RAW files becoming unreadable someday as others (a big reason some advocate converting to DNG). But what I don't like about the RAW workflow (outside of Aperture and Lightroom) are the XMP sidecar files cluttering up my picture folders. So, believe it or not, one of the reasons I do like DNG is because it's tidy. All those metadata files are stored in the container and not out floating around.
I am curious though... do you have a strong argument either for or against converting your RAW files to DNG? If so, I'd like to hear.
Technorati Tags: Adobe Camera Raw, Derrick Story, digital photography, DNG, Photo Downloader, Technology, The Digital Story
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Posted by dstory on April 28, 2008
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I posed this question once to a software developer of a popular RAW converter and was told...
"Personally I don't think you gain much by conversion to DNG. Most software that supports a camera model with DNG will also support that camera models native RAW format as well. Very few programs at this time support DNG files for camera models that they don't natively support as well. The camera manufacturer specific metadata (often known as maker notes) can with some models be lost. Most camera manufacturers own software only supports the camera native RAW format. If you want to be able to process your RAW files with the camera manufacturers software you generally need the original RAW format. DNG is openly documented, but like TIFF (on which it is based) there is a very wide range of possibilities of how exactly it may be implemented. In some cases there may be bugs with the implementation for rare format options. Often there is still quite a bit of per camera model customization necessary to get good results out of a DNG file which only very loosely specifies things such as color rendering, default camera tone curve (not specified at all in DNG itself), default levels of contrast, saturation, noise reduction and so on. Some cameras may look fine with generic DNG default options, others may not."
Sounds to me like a good enough reason NOT to go with DNG.
Commented by: Anonymous at May 2, 2008 12:21 PM
Some other considerations:
- Whether you have a "mainstream" camera. I have a Panasonic DMC-LZ30 which shoots in raw. This is supported by Camera Raw, Lightroom and Bibble, but not by Aperture, Capture One, DXO (in raw mode), or BreezeBrowser. Given that this model is 3 years old, if it's not already supported, it won't happen later. Converting to DNG gives you more options when it comes to conversion at a later time. The potential issues of a format being orphaned in the future are perhaps more important for non-mainstream cameras. Given the rapid proliferation of raw formats, raw converter software vendors are more likely to decide to remove support for older non-mainstream cameras to reduce code bloat. Also, the camera market is in flux, with a number of long-standing camera makers going out of business or being acquired by other companies. This is not an issue for a mainstream DSLR from a big-name maker.
- The size of the raw files. The Panasonic raw files are 15MB for an 8 MP image. The DNG is half that size. If storage space (or backup space) is an issue, then you might want to use DNG, if it's significantly smaller.
Commented by: Kurt at April 30, 2008 12:47 PM
Yes, there are some interesting comments about this on the TDS Flickr Public Group:
http://www.flickr.com/groups/thedigitalstory/discuss/72157604707510520/
Commented by: Derrick at April 29, 2008 05:32 PM
i've heard or read somewhere that while DNG specs are open source, the conversion from RAW to DNG has not been standardized and that different converters will implement it differently. is that correct? if so, that tells me it's a one way street and i might lose data in the conversion process that i'll regret later.
Commented by: c1 asia at April 29, 2008 03:51 PM
Two very interesting comments so far. I really like the points you raise Scott, and I think they are notable depending on the type of backup strategy used.
As for Kevin's question about Windows Explorer, anyone have an answer out there?
Commented by: Derrick at April 28, 2008 04:01 PM
I used to be a diehard DNG advocate, I liked the cleanliness, and the 10-15% saving on file size, that was until my backup strategy changed a bit. I use lightroom, but export XMP changes on the fly. This will write to the DNG and not a sidecar XMP file. Let's say I have 10GB of DNG photos that are backed up, I do small tweaks, add more keywords, and such. When I do a smart backup (write only those files that have changed) all 10GB will write, If I keep with the camera raw files (.crw or .cr2) the changes are written to Sidecar files, and only those are backed up. This is WAY faster, it's less than 8MB. This makes me more likely to backup more often, which is really the key. I'm not worried about files being compatibility being lost, if I see that on the horizon, I will convert my cold storage archives to DNG.
Commented by: Scott E Winklebleck at April 28, 2008 01:29 PM
More a question than an argument: can DNG files be seen natively in Windows Explorer as you can with Raw files if you add the right codec? If so, the its a wash. If not, sometimes I like to look at my pix without opening some bloated software so I just use Explorer.
Commented by: Kevin Purcell at April 28, 2008 11:41 AM
I posed this question once to a software developer of a popular RAW converter and was told...
"Personally I don't think you gain much by conversion to DNG. Most software that supports a camera model with DNG will also support that camera models native RAW format as well. Very few programs at this time support DNG files for camera models that they don't natively support as well. The camera manufacturer specific metadata (often known as maker notes) can with some models be lost. Most camera manufacturers own software only supports the camera native RAW format. If you want to be able to process your RAW files with the camera manufacturers software you generally need the original RAW format. DNG is openly documented, but like TIFF (on which it is based) there is a very wide range of possibilities of how exactly it may be implemented. In some cases there may be bugs with the implementation for rare format options. Often there is still quite a bit of per camera model customization necessary to get good results out of a DNG file which only very loosely specifies things such as color rendering, default camera tone curve (not specified at all in DNG itself), default levels of contrast, saturation, noise reduction and so on. Some cameras may look fine with generic DNG default options, others may not."
Sounds to me like a good enough reason NOT to go with DNG.
Commented by: Anonymous at May 2, 2008 12:21 PM