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Author Topic: I'm confused as hell over Raw vs DNG processing differences and would like help  (Read 18644 times)

Gel

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Sometimes I outsource my editing to a third party company and a lot of the time they suggest I send in compressed DNGs at 2000px across the long edge.
This takes 500 wedding images down in size significantly. But I often hear that editing the images this way (and then getting xmp sidecar files back) will mean the edit is not optimal or will look different when paired up to the raw files on my machine.

This is also a loaded question in that while most of my raw files are from Canon, the Pentax 645z writes PEF and DNG in camera. Should I treat the in camera DNG with the same suspicion?
I only ask this because when I have looked at other editors they state NOT to send DNG's or the edit will look different. I'm talking editing with white balance, exposure correction and curves applied. Nothing more complicated than that.

Can anyone confirm or deny this being the case? I thought DNG was just another container for the same data.

john beardsworth

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DNG has been expanding since it was first introduced. Put simply, DNGs can be the original type which is just like the raw file and contains all the raw data (this is what your Pentax creates), or a later type of lossy or compressed DNG which is much smaller because the raw data is demosaised. The editor should be able to use them for those types of adjustments and, when applied to your raw files by importing the xmp files, they should be almost optimal. The "almost" is because you should review the results carefully to reassure yourself, but any risk is as much about the skills of the editor. So you can try their service and see how close they get.

If other editors don't accept DNGs, maybe it's because they don't use Adobe software or they don't know how to get the adjustments from DNGs back to you so you can apply them to your raw files.
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Gel

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Thanks John, it's reassuring to hear that.

Here's one such company:

https://www.evolveedits.com/faqs/

'RAW files always provide the best results, even when compared to a .DNG file, not to mention the .xmp file that comes with RAW is a huge time saver come delivery. If your process includes working other types of files, this isn’t a problem, just let us know.'

AlterEgo

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Sometimes I outsource my editing to a third party company and a lot of the time they suggest I send in compressed DNGs at 2000px across the long edge.
This takes 500 wedding images down in size significantly. But I often hear that editing the images this way (and then getting xmp sidecar files back) will mean the edit is not optimal or will look different when paired up to the raw files on my machine.

This is also a loaded question in that while most of my raw files are from Canon, the Pentax 645z writes PEF and DNG in camera. Should I treat the in camera DNG with the same suspicion?
I only ask this because when I have looked at other editors they state NOT to send DNG's or the edit will look different. I'm talking editing with white balance, exposure correction and curves applied. Nothing more complicated than that.

Can anyone confirm or deny this being the case? I thought DNG was just another container for the same data.

if you are using Adobe raw converters and you produce DNG files with them or with Adobe  DNG converter of the matching version there shall be no difference between working with DNG or original raw files (except of course possible bugs in Adobe code)... as your adjustments are simple white balance, exposure correction and curves applied your 3rd party retouchers will do just fine with proxies (lossy compressed DNG)... if you are using less DNG friendly converters like C1 then your mileage will (might be) be totally different
« Last Edit: April 06, 2015, 09:14:40 am by AlterEgo »
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eliedinur

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Using lossy reduced resolution DNGs as proxies is exactly what LR itself does when using Smart Previews, except they are slightly bigger (2560 pixels). My experience has been that they are fine for any global adjustments other than sharpening and NR which are better done on the full resolution original zoomed to 100%.
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john beardsworth

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RAW files always provide the best results, even when compared to a .DNG file

No, as they are using Adobe software, the results are absolutely identical whether it's a raw file or a regular DNG. If you send them lossy compressed DNGs, they will probably make identical decisions about adjustments like exposure, highlights etc. They send you xmp files, and you apply them to your raw files. So again, probably no impact on results.

You should check that if you send them lossy compressed DNGs, then they will send you xmp files. That FAQ isn't clear about it - my reading is that they mention xmp in connection with raw files, not DNGs. They would have to know an obscure trick to generate xmp files from the lossy compressed DNGs.

Are you using Lightroom? If so, see the info at https://www.evolveedits.com/lightroom-5-smart-previews/ . This would be the way I would recommend - far less messy and error prone than playing around with xmp files.
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Steve House

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As I understand it, the advantage of DNG over RAW is that the edit information for a RAW file has to be carried by an XMP sidecar file while the DNG can carry that same info in metadata in the file itself, eliminating the need for the sidecar. While the sidecars don't take much space, having two files for each image increases the overall system complexity. My personal workflow is to convert to DNG for import into LR for my working files while copying the original lossless compressed NEF raw file to a second drive as the backup.
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digitaldog

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As I understand it, the advantage of DNG over RAW is that the edit information for a RAW file has to be carried by an XMP sidecar file while the DNG can carry that same info in metadata in the file itself, eliminating the need for the sidecar.
That and any custom DNG profiles one might build but not send along with the DNG. Not having that important piece of the processing could very well produce a disconnect among the parties working on the image. All the little bits and pieces that are scattered about can be embedded into the DNG container (although I don’t think Lens profiles fall into that camp yet).
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AlterEgo

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As I understand it, the advantage of DNG over RAW is that the edit information for a RAW file has to be carried by an XMP sidecar file while the DNG can carry that same info in metadata in the file itself
some OEM raw converters do modify non DNG raw files and write their parametric adjustments inside, there is nothing that prevents any TIFF based file format from carrying whatever you want inside...
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rgs

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I have occasionally converted my RAW files to DNG and I understand that Adobe wants us to do that and they want to make DNG the universal RAW standard. I'm not sure when the sidecar files appear but many of my CR2 RAWs do not seem to have an accompanying sidecar file. I don't know at what level of PP the sidecar is generated but it's not in camera and, it seems, routine PP does not produce it either. So I'm not sure how badly DNG is needed. Although DNG is somewhat successful, it is far from universal and, if Adobe continues to promote their cloud versions at the expense of local machine installs, I may have to change software - at which time I don't want to have to figure out how (or if I can) to convert DNG back to CR2.

So, no DNG for me. It seems smarter to keep the RAW as originally produced by the camera - at least until (?) there is a truly universal RAW format. But then I could be all wet.
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digitaldog

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I have occasionally converted my RAW files to DNG and I understand that Adobe wants us to do that and they want to make DNG the universal RAW standard. I'm not sure when the sidecar files appear but many of my CR2 RAWs do not seem to have an accompanying sidecar file. I don't know at what level of PP the sidecar is generated but it's not in camera and, it seems, routine PP does not produce it either. So I'm not sure how badly DNG is needed. Although DNG is somewhat successful, it is far from universal and, if Adobe continues to promote their cloud versions at the expense of local machine installs, I may have to change software - at which time I don't want to have to figure out how (or if I can) to convert DNG back to CR2.
So, no DNG for me. It seems smarter to keep the RAW as originally produced by the camera - at least until (?) there is a truly universal RAW format. But then I could be all wet.
Adobe treats proprietary raws as read only. So any XMP metadata has to be saved to a sidecar file (or a database). This isn't an issue with DNG, the container can accept this data and since Adobe controls it, they have no issues writing this data in their container. There are many other advantages to the format besides storing XMP data inside a container with raw! Lots more. But if DNG isn't for you, that's totally cool. Be useful to make the decision fully understanding what DNG can provide and where it can be a slight workflow issue. For those of us that understand the usefulness of DNG, well it's darn useful!  :P
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mouse

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That and any custom DNG profiles one might build but not send along with the DNG. Not having that important piece of the processing could very well produce a disconnect among the parties working on the image. All the little bits and pieces that are scattered about can be embedded into the DNG container (although I don’t think Lens profiles fall into that camp yet).

Andrew-
Just ran across your reply and am curious about the inclusion of custom DNG profiles in the DNG file.  It seems that I have two options to create a DNG file from my raw files (NEF). 
--First, simply download the raw images from the card via the Adobe DNG converter to my computer. 
--Second, open the raw (NEF) file in ACR and (before or after editing) select "save image" and select DNG as format. 

I can understand that, if I use the second option, the Camera Profile (custom dcp or otherwise) as selected in ACR will be saved to the DNG file.  If I use the first option (my usual workflow) what, if any, camera profile will be saved to the DNG file?
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digitaldog

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If I use the first option (my usual workflow) what, if any, camera profile will be saved to the DNG file?
Either Adobe Standard or a profile you may have selected as a preset I believe.
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rgs

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Adobe treats proprietary raws as read only. So any XMP metadata has to be saved to a sidecar file (or a database). This isn't an issue with DNG, the container can accept this data and since Adobe controls it, they have no issues writing this data in their container. There are many other advantages to the format besides storing XMP data inside a container with raw! Lots more. But if DNG isn't for you, that's totally cool. Be useful to make the decision fully understanding what DNG can provide and where it can be a slight workflow issue. For those of us that understand the usefulness of DNG, well it's darn useful!  :P

Ok. I can go for that. My problem is simply that I don't trust Adobe much as far as trying first to get the hooks in then turn up the expense. Having said that, I would very much like to know what some other advantages (other than the attempt at universality) are. Maybe DNG is more worth it than I have thought. Can you list some or point me in the right direction?
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mouse

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Either Adobe Standard or a profile you may have selected as a preset I believe.

Thanks Andrew.

Where would the profile be specified within the DNG converter.  I have never seen an option of choosing a dcp profile to be attached to converted files.  Specifically, if I create a custom dcp profile, how do I ensure the DNG converter uses that profile?

Actually, in practise, this is inconsequential.  At some point every DNG file has to go through ACR (or LR), where the custom profile of my choice can be specified as the default.  Correct me if I am wrong.
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Denis de Gannes

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Ok. I can go for that. My problem is simply that I don't trust Adobe much as far as trying first to get the hooks in then turn up the expense. Having said that, I would very much like to know what some other advantages (other than the attempt at universality) are. Maybe DNG is more worth it than I have thought. Can you list some or point me in the right direction?

I find this article provides the main pros and cons and is not unduly long.
  http://www.lightroomqueen.com/articles-page/convert-dng/
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digitaldog

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Where would the profile be specified within the DNG converter. 
It's applied in LR or ACR via the calibration pane or upon import if you have that so set in LR.
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digitaldog

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My problem is simply that I don't trust Adobe much as far as trying first to get the hooks in then turn up the expense.
Then you should also stop using PSD and TIFF as Adobe owns and controls both.

Articles:
http://www.ppmag.com/reviews/200709_adobedng.pdf

http://news.cnet.com/8301-17938_105-57371809-1/adobe-offering-new-reasons-to-get-dng-religion
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AlterEgo

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Then you should also stop using PSD and TIFF as Adobe owns and controls both.
my dSLM does not make PSD or TIFF ... so they stopped
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