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9 Messages

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156 Points

Mon, Apr 8, 2019 10:13 AM

Answered

Camera Raw/DNG: Loss of information when converting raw to DNG

Hello. My questions to developers of DNG concern the DNG format, into which I have been converting all RAW photos, considering that DNG is a complete analogue of RAW. I use Canon equipment. 
1. I recently have found that in many photo contests, if a photo reaches the final and claims prizes, confirmation of the rights to this photo (authorship) in the form of RAW files is required, and the DNG format is not considered as such. 

2. Once I had a claim about a Canon lens purchased - on specific photos as an example. The support required me to submit RAW files. The DNG files were not accepted by Canon support and I was told that they lacked some important information. 

Question 1. Please confirm that when converting RAW to DNG some information is lost, that 
a) does not allow to identify the authorship of the photo, 
b) does not allow to perform photo equipment service support.
Please indicate which information is being lost. 
If the statements written above are incorrect, please give a professional refutation. 

Question 2. What recommendations can you give to avoid the problems described above when using DNG?

I believe that these issues are very important for many photographers around the world.
Thank you!

Responses

978 Messages

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16.6K Points

a year ago

Demanding a RAW file to confirm ownership is meaningless. What if you shot using JPEG? Or on film?

Canon would need to let you know what data is missing. Many vendors have their own proprietary data that is not industry-standard and the DNG spec wouldn't deal with that. I'm not sure why its a big deal- shoot a sample photo and send the RAW file.

Or, embed the RAW inside the DNG.


9 Messages

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156 Points

Thank you, David!
1. Regarding the photo contest, it would be more correct to say about the authenticity of the photo, not about the authorship. Here is a quote from the rules of the one contest in my translation:
"Also, in order to establish authenticity, it is necessary to provide RAW files (.CR2, .NEF, .ORF, .PEF, etc.) or original uncorrected JPEG files ... DNG files are allowed only if they are the main format of the RAW camera"

2. Here is the answer of Canon support in my translation:
"ORIGINAL files in both JPG and RAW format contain extensive service information based on which we can often draw some conclusions. Any conversion of the original files leads to complete or partial loss of it and partial or complete loss of even standard EXIF ​​information. This does not allow us to make any reasonable assumptions about the reasons for the occurrence or the presence of problems when analyzing images. Converting original RAW files to DNG format leads to a loss of debug information. We can not comment on whether there is a loss in image quality and the possibilities of its processing in this transformation."

I use old Canon EOS 6D camera.

Champion

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2.1K Messages

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36.3K Points

a year ago

It's my understanding that Adobe includes all camera manufacturer proprietary data in the DNG file in MakerNotes. Adobe will sometimes support a new camera model with a new feature such as Canon's 'dual-pixel' technology before supporting that specific feature. In most cases Adobe will attempt to support the new feature in an update, which they did for Canon 'dual-pixel support in LR 6.8.

https://helpx.adobe.com/x-productkb/multi/editing-canon-dual-pixel-raw-cr2.html

As far as authorship is concerned the camera embedded copyright information in a raw file cannot be overwritten using LR, but there are many other metadata editors that can. Given that fact I don't see how a camera raw file proves authorship any better than a DNG file. Perhaps someone else landing here knows otherwise and will respond.

https://en.wikipedia.org/wiki/Comparison_of_digital_image_metadata_editors




9 Messages

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156 Points

Thank you, Todd!
See, please, my comment given above on David’s answer.

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2.1K Messages

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36.3K Points

"ORIGINAL files in both JPG and RAW format contain extensive service information based on which we can often draw some conclusions. Any conversion of the original files leads to complete or partial loss of it and partial or complete loss of even standard EXIF ​​information.
That's would be the case for "conversion" to JPEG, TIFF, or DNG file format. However, I believe some of the metadata editors at the link I posted simply copy ALL of the raw CR2 file data and then only change specific non-proprietary EXIF data. This shouldn't disturb any Canon "service information," at least from the standpoint of a non-Canon staff person examining the file (i.e. contest judges).
 Further, Canon's raw editing software (DPP) can "change" information in the file as a 'Save' operation, which makes it no longer an "original" file. User who do so cannot submit these Canon SW edited files? I'm remain skeptical of the value for such a restriction. As they say "Rules are Rules," but often able to be broken!

9 Messages

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156 Points

I have started this conversation in the hope of getting arguments in defending my rights for photo equipment service and participation in photo contests, since all my photos are now in DNG format.
As far as I understand, the answer of the Canon service was given about all possible forms of converting RAW to DNG, regardless of what program was used. At the same time, they did not even ask me what programs I use. Information is lost - that's all!
But I converted the photos in question to DNG when importing from them from flash drive to a disk in LR.
Todd, one personal question: are you a representative of the Adobe development team? If not, do you know how to draw their attention to my questions?

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2.1K Messages

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36.3K Points

Todd, one personal question: are you a representative of the Adobe development team? If not, do you know how to draw their attention to my questions?
No I am not, but Adobe Engineering does monitor posts in this forum.

IMHO it's a question that has only one "academic" answer. Neither raw files or DNG files are valid proof of ownership since the file metadata can be edited without detection by lay people (i.e. judges). However, there is one possible way to prove original file ownership of the images through use of the file's Maker Notes Serial Number field. The camera would then have to be physically inspected by the judges to confirm that its serial number, make and model matches the file data. Lacking that a DNG file is just as valid proof of ownership as an original raw file.

978 Messages

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16.6K Points

I'm not sure that getting service or entering a contest is a "rights" issue. For service, you must still have the lens or you wouldn't care. So shoot a few RAW files and send them.

Contests, well, that's up to the judges. What Adobe says is irrelevant.