DNG vs RAW

[sanyasi]

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I am curious what the distinction is between RAW and DNG. Specifically, I understand that RAW is what comes out of the camera and is camera specific and that DNG is a universal format. What I am focused on is Lightroom edits. I recall reading that with DNG, Lightroom creates a sidecar file with the edits. This would seem to be preferable in the event the Lightroom catalog becomes corrupt, together with the backup?

 

Any thoughts?

 

Jack Siegel

[ho_co]

Jack, as I understand it, RAW is the general term. DNG is one type of RAW, as are RWL (D-Lux 4), NEF (Nikon), etc. DNG was invented by Adobe to be universal and hopefully reduce the proliferation of camera-specific formats. Of course, when Panasonic introduced cameras that wrote additional information to the RAW file, Adobe had to change the DNG specification to accommodate the new instructions.

 

RAW is in all cases what comes out of the camera, though the camera manufacturer can and does massage the data before they're dumped to the card. (See, for example, ChromaSoft: Visualizing DNG Camera Profiles Part 1.) Some manufacturers use proprietary RAW formats, others use DNG for the purpose.

 

The intended universality of DNG has yet to be realized.

 

 

Lightroom handles all original files non-destructively. It writes sidecar files alongside the proprietary RAW files if for no other reason than that Adobe has no rights to write or modify RWL or NEF files. In the case of DNG, contrary to what you've understood, Adobe products currently write your processing instructions directly into the DNG. It's still non-destructive, because your settings can be changed or deleted by editing the DNG.

 

Some people aren't happy with the fact that Adobe treats proprietary formats and DNGs differently. (See, for example, http://www.l-camera-forum.com/leica-forum/digital-post-processing-forum/104239-does-lr-alter-your-referenced-raw.html.)

 

 

I don't think either method is 'better' for a damaged catalog. The catalog is just the index to the various image files. If it becomes corrupt, no damage is done to your images (assuming you've stored them somewhere that didn't go up in smoke when the Lightroom catalog did), though you may now have much more difficulty turning up a specific one.

 

Actually, a theoretical disadvantage to the use of sidecar files is that you now have two files to keep up with if you decide to move the file to another folder, for example. But in fact, Lightroom or Photoshop takes care of the logistics automatically when you transfer the files from within the software rather than from the Finder.

 

 

But those are opinions I'm ready to see corrected by more knowledgeable forum participants.

[LuxBob]

I can add nothing to what Howard said regarding the differences but would add that attempts to set standards in a world where the technology is still developing usually fail, rightly so.

The problem that I see with this is how long term do we preserve our stock? There are problems in terms of how durable the various media are in the long term, how long will suppliers maintain those physical interfaces, ditto software interfaces and how long will the various formats remain in use. Usually there are upgrade paths but not always.

Although I am about 99% digital, good old film does have some advantages when it comes to long term storage. Apologies for taking this somewhat O.T.

[sandymc]

It's still non-destructive, because your settings can be changed or deleted by editing the DNG.

 

One addition to what Howard has said - the changes that Adobe products make to DNGs are non-destructive if what you use to read the modified file correctly implements the full DNG spec. Many non-Adobe products, for example Capture One, only implement enough of the DNG spec to read specific camera files, and may not be able to correctly decode a modified file.

 

Sandy

[jaapv]

I can add nothing to what Howard said regarding the differences but would add that attempts to set standards in a world where the technology is still developing usually fail, rightly so.

The problem that I see with this is how long term do we preserve our stock? There are problems in terms of how durable the various media are in the long term, how long will suppliers maintain those physical interfaces, ditto software interfaces and how long will the various formats remain in use. Usually there are upgrade paths but not always.

Although I am about 99% digital, good old film does have some advantages when it comes to long term storage. Apologies for taking this somewhat O.T.

There is no reason to suppose that software will simply go up in smoke when a format becomes obsolete. Either the support will be rather indefinite ( for instance Bitmap) or there will be conversion programs floating around on the Internet. Film, however - there has plenty been lost in fires and gone up in smoke...

[Jamie Roberts]

There is no reason to suppose that software will simply go up in smoke when a format becomes obsolete. Either the support will be rather indefinite ( for instance Bitmap) or there will be conversion programs floating around on the Internet. Film, however - there has plenty been lost in fires and gone up in smoke...

 

...not to mention colour shifts, etc... Physical storage of film is at least as difficult and probably more fraught with difficulty these days than, say, storage of TIFF files (the TIFF spec goes back to the mid-80s at least).

[roguewave]

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Howard, I'm glad you included Roger's thread. I still believe that the the most important issue is to have a separate copy of the original RAW file. When I mean separate, I mean that the original Raw file is saved in one place & then a copy of all the raw files to be converted to DNG's is made before the conversion to the DNG format. Don't ever use the original RAW files for conversion. Make a second copy of all the RAW files & convert them, not the originals. This gets lost in the details. Adobe changes things when you convert & when you copy & convert.

[haroldp]

There is no reason to suppose that software will simply go up in smoke when a format becomes obsolete. Either the support will be rather indefinite ( for instance Bitmap) or there will be conversion programs floating around on the Internet. Film, however - there has plenty been lost in fires and gone up in smoke...

 

In addition, my digital photo's (mostly RAW, some old jpg's) are multiply backed up, both onsite, offsite, and in the cloud.

 

I can also easily find every digital photo I ever took. Not so my chemical photos.

 

The one storage format that has survived intact through multiple computing generations is the hard drive. As they increase in capacity, I regularly copy directories to newer drives.

 

Other media both optical and magnetic have come and gone.

 

Regards ... Harold