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Author Topic: Looking for technical literature on converting to DNG, editing, and exporting  (Read 809 times)

jeffh

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First and foremost, I am not looking for everyone's opinions on whether converting to DNG is a good idea or not. There are plenty of those opinions online already, and I have read many of them. I want to form my own opinions from factual information... I just haven't found the facts yet.

So, what I am looking for is a detailed and accurate description of what happens when a raw file is converted to DNG, brought into an editor such as Lightroom or Photoshop, and then exported for print. I would imagine that this amount of detail could occupy a chapter within a book, or even an entire book in itself. Can anyone recommend a reputable text that covers this topic in depth?

Thanks!
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kirkt

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Here is the current (v1.4) DNG Specification document from Adobe:

http://wwwimages.adobe.com/content/dam/Adobe/en/products/photoshop/pdfs/dng_spec_1.4.0.0.pdf

And here is an overview of the DNG file format from dpbestflow.org:

http://www.dpbestflow.org/DNG

and a bit about the archival aspects of DNG:

http://www.dpbestflow.org/file-format/archive-file-formats

Hopefully this gives you an idea of what happens to your raw file when you convert to DNG and then use that file to start you r editing workflow.
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Dave Ellis

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First and foremost, I am not looking for everyone's opinions on whether converting to DNG is a good idea or not. There are plenty of those opinions online already, and I have read many of them. I want to form my own opinions from factual information... I just haven't found the facts yet.

So, what I am looking for is a detailed and accurate description of what happens when a raw file is converted to DNG, brought into an editor such as Lightroom or Photoshop, and then exported for print. I would imagine that this amount of detail could occupy a chapter within a book, or even an entire book in itself. Can anyone recommend a reputable text that covers this topic in depth?

Thanks!

Hi Jeff

The references listed by kirkt are a good starting point to learn about DNG. The DNG spec is a bit "heavy going" but Chapters 5 and 6 give a good indication of Adobe's approach to raw conversion. Once the initial raw conversion is done, the rest of the process of editing and printing is exactly the same, irrespective of whether a proprietary raw file or DNG file is used as the starting point.

In fact the raw conversion process is much the same too as the raw data that has to be converted is the same in the DNG file as the raw data in the original raw file. The DNG file contains some extra information that can be used in the raw conversion process but basically the same things must happen for both the raw and DNG files. One difference with the DNG file is that adjustment settings made during processing are stored in the file itself whereas when the raw file is used the adjustment settings are stored either in the LR database or in a sidecar XML file in LR or ACR.

Dave
« Last Edit: January 28, 2017, 01:55:34 AM by Dave Ellis »
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jeffh

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Thanks for the suggestions!
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scyth

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One difference with the DNG file is that adjustment settings made during processing are stored in the file itself

or in a sidecar (.XMP) or in a database = it all depends what you decide w/ a particular software ...
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scyth

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So, what I am looking for is a detailed and accurate description of what happens when a raw file is converted to DNG

unfortunately the only way to do this is to look @ the source code of the specific converter ... and ACR/LR/DNG converter are not the only ones that do "raw" to "dng" conversion (and they are not available in their source code form)... to get as close to the situation as possible you can only / need to look @ DNG SDK ( not DNG specification, which also does not described the actual conversion process ) = https://www.adobe.com/support/downloads/dng/dng_sdk.html  ... take a note, while version says "1.4" on the webpage the code is actually silently being updated by Adobe (so what you download today might not be what will be there tomorrow)... so you need to see rev. changes in the actual C++ code to see what bugs Adobe fixed ( hopefully you save the original raw files  ;D - bugs related to the actual conversion process done by ACR or LR or DNG converter are not there )
« Last Edit: February 04, 2017, 12:44:15 PM by scyth »
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scyth

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And here is an overview of the DNG file format from dpbestflow.org:


and those are again = "those opinions online already" as OP said
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