Alteration of DNG's?

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My workflow is to convert my NEF images to DNG's while importing my cards into Lightroom. I have not archived the original NEF's.

Now I am in a circumstance that I may have to prove that my DNG's are
as-shot from the camera, and not altered in any way. Is there a way to do this? Can DNG's be altered any more easily than NEF's? Is one format more legally or electronically immutable than the other?

Thanks for all help.
 
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Welcome to Lightroom Forums grohfoto!

Your DNGs ARE pristine as shot with just a different standard container format. If you think that what you saw on the camera's screen as being the not altered ones, then NEFs aren't either. That said, what you see on screen is an altered version rendered from the original unaltered data because any raw file do have to be rendered/interpreted somehow whatever the program used.
 
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I forgot to add that NEF (raw) files never get overwritten by Lightroom except for the capture date if you explicitly tell Lightroom do to so. As a consequence, writing data to XMP will create a separate XMP file for those. DNG files self contain the XMP data so can be overwritten but just in part as the raw data part in them is still never overwritten. Somehow, DNG = NEF + XMP
 
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[quote author=Denis Pagé link=topic=9'47.msg6'91'#msg6'91' date=1264544788]
Somehow, DNG = NEF + XMP
[/quote]NEFs are an extension of the TIFF6 standard and so is DNG. Each consists os a header segment and a data segment. The DNG header can contain the EXIF, IPTC and an XMP section. The NEF contains at least the EXIF, and certainly not the XMP. The data segment of the NEF is compressed and probably other things , while the DNG data segment can be compressed or uncompressed and linear (RGB) or mosaiced.
 
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To ask the question another way, is there any way that a manipulated image can be saved as a DNG and represented as an original, straight-off-the-camera image? Or, is the RAW file incorporated in the DNG always intact and legally/morally accepted as the actual capture?

Is there any reason to save both RAW files from the camera plus the DNG conversions? Are they not the same as far as integrity of information?

Finally, I am not so naive as to think that any image can't be manipulated. Any reason to believe that a DNG would have less veracity than an NEF or a CR2 in a legal setting, or in a photocompetition?

Appreciate your facts and thoughts.
 
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We're probably not the right folks to ask that question of. I think it would be almost impossible to manipulate a raw image without proprietary information from the camera/sensor mfg'r. A DNG perhaps a little less impossible, because of the 'openness' of the Adobe specification, but still a technical challenge.

I have read of, but not followed, discussion concerning hash codes embedded at shutter time, by certain cameras/mfgrs which can almost provide a 'fingerprint' of authenticity. I said 'huh, how about that' and moved on.

I know of folks who do a DNG conversion and also save the native camera raw file as well in their backup strategy.

Because the DNG file is in fact writable in certain segments, although not in the raw data segment, I presume it could be said that it's a little bit less trustworthy, but I think we're talking serious hacking to get in there.

Good enough for photo judges? Probably. Good enough for the Supreme Court, who knows?
 
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[quote author=grohfoto link=topic=9'47.msg6'933#msg6'933 date=126456279']
To ask the question another way, is there any way that a manipulated image can be saved as a DNG and represented as an original, straight-off-the-camera image? Or, is the RAW file incorporated in the DNG always intact and legally/morally accepted as the actual capture?
[/quote]The RAW files that come out of my camera are DNGs. There are at least 12 camera manufacturers that either offer DNG as an optional RAW format or it is the only RAW format produced by their camera. If I had to go to court with my image, I'd want to have the one that came from the camera be it NEF, CR2 or DNG. If I were entering a photo competition, I would certainly insist that a DNG be an acceptable source file.
 
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If I am correct in my thinking NEF's get written to by NX so I guess there is no difference there from DNG. If you wanted an NEF to be authenticated I believe you would need the specific Nikon software.
 
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[quote author=grohfoto link=topic=9'47.msg6'933#msg6'933 date=126456279']
Finally, I am not so naive as to think that any image can't be manipulated. Any reason to believe that a DNG would have less veracity than an NEF or a CR2 in a legal setting, or in a photocompetition?
[/quote]
If you're talking forensic levels, then that's a specialist field. You could try asking the guy behind http://forensicphotoshop.blogspot.com/ and there's someone else whose name escapes me. Jurisdictions will vary in what is permissible. And perhaps because DNG is, in a sense, a derivative of the NEF, the introduction of some element of doubt may be sufficient to make a DNG less credible in court - even after the provision of evidence that it would be the same as the NEF original.

If it's merely a competition, a reset version would be decent evidence. And don't forget Capture NX lets you do monkey business with NEFs too...

John
 
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