Are all DNGs created equal?

[edslaughter]

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I'm confused about .DNG files and hope someone can enlighten me.

 

I had assumed that as an industry standard a DNG file was a DNG file, and that any program that could read some could read them all.

 

If so, this seemed to imply two possible workflows: first, what I now have, is one where a camera makes a RAW file and a separate program (for example Adobe RAW Converter) turns is into a DNG which can then be read by any program that knows about DNGs.

 

The other flow would be a camera (say a Leica or a Ricoh GR) that makes a DNG directly. I had assumed that those DNGs could be read by any program that uses DNGs just as if they had been made as output from Adobe RAW or some other converter.

 

But instead I read that some programs (Aperture?) can't read Leica DNG files until a new version of the program is released that specifically supports the DNG from a particular new camera.

 

Is this true? If so, does anyone understand what the issue is?

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[jrgeoffrion]

I'm confused about .DNG files and hope someone can enlighten me.

 

I had assumed that as an industry standard a DNG file was a DNG file, and that any program that could read some could read them all.

 

If so, this seemed to imply two possible workflows: first, what I now have, is one where a camera makes a RAW file and a separate program (for example Adobe RAW Converter) turns is into a DNG which can then be read by any program that knows about DNGs.

 

The other flow would be a camera (say a Leica or a Ricoh GR) that makes a DNG directly. I had assumed that those DNGs could be read by any program that uses DNGs just as if they had been made as output from Adobe RAW or some other converter.

 

But instead I read that some programs (Aperture?) can't read Leica DNG files until a new version of the program is released that specifically supports the DNG from a particular new camera.

 

Is this true? If so, does anyone understand what the issue is?

 

Yes, it's true. DNG is a nice concept but many things are missing from its specifications (lens information for example). DNG is nothing more than a RAW TEMPLATE that stipulates which information needs to be collected and where this information resides. Nothing more. It speeds up the reverse engineering required for software developers to add a new camera/model to their database. Unfortunately, it's not an "open standard" in the sense that it is "dictated" by Adobe without any outside input (to my knowledge).

[geoff]

DNG is not an open standard in the sense that data stored in a DNG file can, and most often, contains proprietary information about a particular camera model. It is definitely not a Rosetta Stone which converts every different type of RAW camera file into an open, universal or unified format. This is a myth in as much as it is to expect any such solution in the first place. However, I believe that Adobe, with DNG, has strived to go as far as possible in this area.

 

As I currently understand it, DNG files are wrapper files that contain separate components. One for RAW image data and another for details specific to the camera itself, which is needed to conduct a RAW conversion.

 

This second bit of information is usually proprietary. That is why Aperture and all other RAW developer applications, that offer DNG support, also need to understand a camera’s proprietary information in order to open a DNG version of an image from said camera.

 

Therefore one DNG file is not necessary the same format as another DNG file. The placeholder structure is the same but the contents may vary.

 

The illusion stems for the fact that Adobe does a very good job at supporting the proprietary RAW files from the broadest range of cameras, in the first place, and thus by default enables the support of DNG files derived from these cameras. Even Rawshooter notes on there supported camera list which DNG files are supported and which are not.

 

I know that this may fly in the face of conventual perception of what DNG is and the associative benefits, but this is the information I have come across in attempting to thoroughly investigate the issue.

 

A simple Google search will turn up a lot of information about this issue. Another good place to learn more is at the OpenRAW website.

 

Additionally, is important to understand that Aperture, itself, has little to do with which camera RAW files are read and which are not. It is specific files with in Mac OS itself that contains this information which Aperture references. Likewise, Aperture relies on the Core Image technology of Mac OS X as the RAW conversion engine.

[Guest guy_mancuso]

This has been the big debate that it is and was intended for open standard but it is not , well said guys

[nemeng]

What the other blokes said.

 

See also the FAQ entry at:

 

Leica FAQ - Digital Accessories & Issues

[edslaughter]

Thank you all very much for the prompt, helpful, and unwelcome explanation. I'm disappointed but I guess I'm not surprised.

 

I was a little confused, however, since I could download the purported M8 DNG and open it in the ancient version of the Camera Raw plugin that I have on my PS CS1 software--a plugin written a year or two before the M8 came out.

 

I guess this means that either Leica did a good job a making a .dng file that contains no proprietary info, _or_ that whoever posted the .dng actually opened it in one program that understood it, but then saved it as a slightly different, more "universal" .dng.

 

(There must be something rather like that, since I can use the latest standalone Adobe Raw Converter to convert the RAW from the latest camera to DNG, and then open that DNG in my old CS1 Camera Raw, which never heard of the new camera and which can't open the RAW file from it.)

 

All rather random and complicated. It sounds like we're still in the bad old days where the question of whether you can use Camera X with software Y on machine Z is a contingent, moving target and all you can do is check with others about the specific combination before you buy.

[geoff]

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I guess this means that either Leica did a good job a making a .dng file that contains no proprietary info, _or_ that whoever posted the .dng actually opened it in one program that understood it, but then saved it as a slightly different, more "universal" .dng.

 

(There must be something rather like that, since I can use the latest standalone Adobe Raw Converter to convert the RAW from the latest camera to DNG, and then open that DNG in my old CS1 Camera Raw, which never heard of the new camera and which can't open the RAW file from it.)

 

Very interesting and very frustrating. It would be nice if we could just get some straight, complete, and open answers from the likes of Adobe, Apple, and Leica with regards to RAW and DNG support. Is there anything to hide from the public?

 

BTW, I’m downloading the Aperture 1.5 and Mac OS X 10.4.8 as I write. I can testify that Aperture 1.1.2 with Mac OS X 10.4.7 does not work with the Leica M8 DNG file, that's floating, around. It behaves just like DMR files with a small JPEG preview display.

[nemeng]

BTW, I’m downloading the Aperture 1.5 and Mac OS X 10.4.8 as I write. I can testify that Aperture 1.1.2 with Mac OS X 10.4.7 does not work with the Leica M8 DNG file, that's floating, around. It behaves just like DMR files with a small JPEG preview display.

 

On the other hand, an old version of DCraw running as a unix command line tool via Mac OS X v10.3.9, opened and processed the M8 sample DNG files just fine. No problems. Good colour, sharpness etc.

 

The only glitch so far is that the current version of DCraw cannot extract the thumbnail in the M8 DNG file. Well, it can, but not in any form which is readable on my machine :?)

 

Which all means... brand-new DNGs are prefectly readable by legacy RAW apps IF THE CONVERSION SOFTWARE IS WRITTEN INTELLIGENTLY.

 

Apple's Aperture appears to ignore the camera/chip meta-data inside DNG files. Try to open a DNG file from a camera not on their list and... problems. As noted by many others, this is actually poor programming by the Apple team, and not an inherent fault in the DNG spec.

[ho_co]

Very interesting and important information! Thanks.

 

I think this question is not off track for this thread; let me know if I should post it elsewhere instead.

 

When running Adobe DNG Converter, one has the choice of embedding the original RAW image or not.

 

Seems to me a strange question. If I'm converting, say, a Digilux 2 file to DNG:

1) I'm converting to DNG because it's supposedly more permanent than RAW, so why save the RAW?

2) A program that reads DNG can't read an embedded D2 RAW.

3) A program that reads D2 RAW can't extract it from a DNG.

4) So basically, if I wrap the DNG around the RAW, haven't I lost access to the RAW file anyway?

 

So is there an advantage to embedding the RAW image? If so, what is it?

 

Thanks.

 

--HC