DNG: Are there multiple DNG formats out there?

[robert_ades1]

I got this message from DxO. It was my understanding that Adobe's DNG RAW

format was intended to be universal, open source code, so that hopefully all the

camera manufacturers and software would eventually come on board to a universal

standard. DxO is saying that there are at least two DNG formats. Can anyone

explain this?

 

Quote:

--------------

Finally in regards to the question about Lightroom.

 

It is not possible for Lightroom to read DxO DNG files because they are

different types of DNG files.

 

DNG (Digital Negative) format is Adobe propritary. There actually 2 kind of DNGs.

 

- Raw DNG or CFA DNG (colored Filtered Array): contains raw image data + added

meta data and is not demosaiced. This Raw format is (usually) 4 channels coded

with 12 bits (sometimes 14 bits) color depth.

 

- Linear DNG: contains RGB image data and is demosaiced. Linear DNG format is 3

(or more) channels coded with 16 bit color depth. Due to the bit depth coding,

the size of a linear DNG is larger and much more important than a Raw DNG.

-------------

End Quote

[mtwhite]

It reminds me of an old saying in the computer industry. "Standards are wonderful! There's so many to choose from!"

[kevin_schoedel]

There is one (current version of the) DNG format (described <a href="http://www.adobe.com/products/dng/pdfs/dng_spec.pdf">here</a>). The specification allows for a number of variations in how the raw image data is stored, since not all cameras have the same kind of sensor. As the message says, the raw image data can be stored either in CFA form (for cameras with Bayer type sensors) or in linear form (for Foveon or triple sensors, or for processed images). The implication of the message is that Lightroom does not read some valid DNG files, which sounds a bit dubious.

[colinsouthern]

It's not accurate to say that DNG is a proprietary format - it's very much an open standard.

 

Personally I'd find it very strange if lightroom couldn't open a DNG that conformed to the standard.

[john falkenstine]

Adobe clearly states on their netsite that DNG is an open platform. The intent of DNG is to avoid the cyberbabble of different RAW file formats. It think its a good idea.

[randmcnatt]

Was that an email from Dxo tech support? I've had some very wierd correspondence with them, like the time they tried to convince me that Dxo won't reprocess an image because it rewrites the RAW file. Maybe they have a slow link to Bablefish, but sometimes they don't seem to make any sense.

[godfrey]

There is one DNG specification. It is owned by Adobe and is publicly disclosed. Lightroom will

read DNG files, both CFA and Linear encoded. You can create them with DNG Converter from

a native format RAW file and import them into LIghtroom.

 

I notice they don't tell you what form of DNG file they produce. It sounds like they have not

implemented their DNG output files in compliance with the DNG specification.

 

Godfrey

[Spearhead]

Bibble can't read Ricoh DNG files. I'm not sure why, but they can't. They do support other cameras that ouput DNG. Something interesting here...

[colinsouthern]

"There is one DNG specification."

 

So far, there have been 2 versions of the DNG specification. Version 1.0.0.0 was published when DNG was launched in September 2004, with the simultaneous release of "2.3" (ACR and DNG Converter). Version 1.1.0.0 was published in February 2005, but was used in "2.4" released in January 2005.

[robert_ades1]

Thank you everyone for your replies. For whatever reason, DxO 4.5 (the current release) is designed to be compatible with Lightroom, but the files DxO creates for Lightroom are either JPEG or TIFF, but not DNG. This seems rather odd considering the fact that DxO will produce DNG files that are easily accessed by Bridge, ACR and PSCS2.

 

So I can't understand it.

 

I've owned DxO software for a long time, and their processing algorithms are pure genius, but their software design needs more work. It's always frustrating.

[eugene_scherba]

<p><i>their processing algorithms are pure genius</i></p>

 

<p>I don't get what is so special about DxO. PTLens does lens distortion + chromatic

aberration + vignetting correction for $10. Photoshop CS+ Lens Correction tool corrects

chromatic aberration for free (if you have Photoshop).</p>

 

<p>Pure algorithm-wise, <a href="http://www.iridientdigital.com/">Raw Developer</a>

has the absolute best demosaicing I have encountered so far, besting ACR (admittedly, I have

not tested DxO yet).</p>

[robert_ades1]

DxO is the only software to date that can calculate on each of the three RGB layers, on a per-pixel basis, the errors for each lens/sensor pair. For instance, PT Lens, which is great in its own right, only considers the lens defects itself, but the measured impact on a particular camera lens sensor. DxO also measures the noise at each ISO for each camera sensor and can apply reverse algorithms to cancel out that noise.

 

ACR can correct some of the chromatic aberation in an image, but it cannot do so with the precision of DxO, because again, DxO measures the abberation for individual pixel, not for the image as a whole.

[howard_slavitt2]

DxO outputs to linear DNG files. I have been processing Canon 5D files in DxO (just using chromatic aberration and vignetting corrections) and outputting them to LINEAR DNG files, and then opening them in Lightroom. They are essentially identical to files that I open for the first time in lightroom. The difference is that the DxO, linear DNG files, have already been demosaiced, and have also had the few corrections I've done to them applied. The Raw DNG files, are not demosaiced; for those files Lightroom does the demosaicing.

[qtluong]

<i> I got this message from DxO.

Quote: -------------- Finally in regards to the question about Lightroom.

 

It is not possible for Lightroom to read DxO DNG files because they are different types of DNG files.

</i>

<p>

Either this reply is mistaken, or DxO broke something, because I can certainly read the DNG files processed by DxO v3 in Lightroom 1.1.

Lightroom reads both linear and raw DNG files.

[robert goldstein]

<p><em>Late, late response for those who may find this thread in a search about linear DNG or DxO.</em></p>

<p>DxO Optics Pro is currently up to version 5.3.3. It can still produce linear DNGs which are most definitely readable by Lightroom/ACR. It is important to understand that these are not RAW files, and some information may not be carried over into the DNG. For instance, if Dxo clips highlights, the highlights will remain forever clipped in LR or any other digital editor. Clipped shadows, in contrast, are virtually completely recoverable, a disparity that I do not understand. On the other hand, DxO can do a superb job at highlight recovery, far superior to LR/ACR in my experience. So, the trick is to set DxO's "Exposure Compensation" control to "slight" so that it will automatically recover highlights. On some images, you may need to go to a stronger level to accomplish this, but the software is very good at pulling detail out extreme highlights.</p>

<p>So is it worth the effort to use Dxo as a prelude to LR/ACR rather than just processing directly in the latter? My answer is a very strong "yes." The RAW conversions from DxO are far superior to what I can get in LR, no matter how hard I try. I have done a great many comparisons, and believe me, the DxO processed images are much sharper, cleaner and more detailed, and they have a level of 3D modeling that I have not seen with any of the RAW processing programs that I have tried.</p>

<p>Rob</p>