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Extracting Full Size JPEG Preview From Enhanced Super Resolution DNG

Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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What is the most efficient way to create and extract a full sized JPEG from an Enhanced Super Resolution DNG generated from a camera RAW file?

 

When I use the Enhance/Super Resolution function on a CR2 image, LR generates only a medium-sized embedded preview JPG with the created DNG file. (I had hoped that by setting JPEG Preview to Full Size in LR's Preferences/File Handling/Import DNG Creation, the Previews created by Enhance would also be full size.  Alas, this setting seems to have no effect on this behaviour.)

 

Once I have created the Enhanced DNG, I can upgrade its embedded JPG preview to full size by using the /Metadata/Update DNG and Metadata command. After that, I can achieve my goal of extracting the large enhanced JPG. (I use RawPreviewExtractor by LibRaw LLC.) At this point in my workflow, I generally keep the extracted JPG and original CR2 file, and delete the generated DNG to save a lot of space.

 

Step 1, generating the enhanced DNG from the CR2, and step two, using Update DNG to upgrade the DNG's embedded JPG preview to full size, are both very time-consuming processor-intensive functions. 

 

To save time and to simply the workflow, is there some way that I can force LR to embed a Full Size preview JPG Preview when creating a DNG using Enhance/Super Resolution, so that I do not have to reprocess the resulting DNG using the Update DNG feature?

 

If there is no way to do that, then I would like Adobe to treat this as an app improvement request.

 

Thank you,

 

David

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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The correct name of the command under Library/Metadata menu that I referred to in the 3rd and 5th paragraphs of my original post is "Update DNG Preview and Metadata", not "Update DNG".

 

David

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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AFAICT the most efficient way is to have LrC export a full-size JPG from each one. That gives you close control over the specifics, and you can leave LrC to process through a batch of images while you get on with something else. It does not include the step of re-writing a very large DNG file to disk with updates, nor the step of re-extracting a preview that must then be re-written to disk as a new JPG anyway. It just goes straight to this desired result. 

 

Afterwards you can delete this same highlighted set of enhanced DNGs - again, from inside LrC.

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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Thanks @richardplondon.  Please see my reply to @GoldingD.

 

-David

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LEGEND ,
Mar 15, 2023 Mar 15, 2023

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Why are you trying to extract an embedded preview from a DNG instead of simply exporting to a JPEG?

 

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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Why are you trying to extract an embedded preview from a DNG instead of simply exporting to a JPEG?

 

 

I am trying to extract an embedded full res super res enhanced preview JPEG from the enhanced DNG rather than exporting a JPG from it in the hopes that this will save me that step, and time.

 

The Enhance / Super Resolution command already creates a DNG which contains an embedded JPG preview.  That JPG preview can be extracted from the DNG almost instantly.  (The RawPreviewExtractor tool that I mentioned can extract the full res JPG previews from hundreds of DNGs in a second or two).  

 

The alternatives for generating a full sized JPG from the Super Res DNG, either "Update DNG Preview and Metadata"  then preview extraction, or Export JPG, take considerably more processing and time to produce those JPGs.

 

The problem for me is that the preview JPG embedded in the DNG generated by Enhance + Super Resolution is much smaller than the full size of the super res image.


If
 Enhance / Super Resolution is instead somehow able to embed a full res JPG preview in the DNG rather than a medium sized one, then only one extremely rapid processing step after Enhance/Super Res would be required to create a set of full resolution JPG from a set of edited and enhanced camera RAW files. 

 

If Enhance / Super Res cannot do that, then I suggest that Adobe consider modifying the Enhance / Super Resolution feature to allow a user to optionally choose that the embedded JPG preview be full sized.

 

- David

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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The problem for me is that the preview JPG embedded in the DNG generated by Enhance + Super Resolution is much smaller than the full size of the super res image.


By @David A. Gilmour

 

So instead of using Metadata/Update DNG and Metadata to embed a full size preview, simply export a JPEG at full resolution.

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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So instead of using Metadata/Update DNG and Metadata to embed a full size preview, simply export a JPEG at full resolution.

 

Thanks @john beardsworth . That is the next best alternative, no doubt. 

 

When Exporting JPGs from DNGs, LR may take a few seconds to generate each exported image, depending on processing power, etc. In comparison, extracting the embedded JPEGs from a set of hundreds of DNGs takes only a second or two. Based on the tests that I have done with my setup, the latter process is on the order of hundreds of times faster. When processing many large batches of images, the time saved by extracting rather than exporting could be substantial.

 

Enhance + Super Resolution always generates and embeds a preview JPG in the DNG. Unfortunately it is a low res preview.** If there is a way to have LR embed a full res preview rather than low res, then the job would be nearly done, save the very rapid extraction step.

 

**That in itself feels to me like a curious design choice for the Enhance/SR feature. Why not generate an embedded preview that matches the super resolution of the  DNG? The difference in filesize between a Enhanced+SupRes DNG file with an embedded low res preview versus a full res one is very small.

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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Are you certain Enhance is not just copying this low-res preview data from its source? 

 

IMO if you are unhappy with how long it would take to Export a super-res JPG, you will equally be unhappy with how long EXTRA it would take to generate one and embed it into the DNG. Whether when that was being originally generated, or during a later Metadata snd Preview update. Those are surely, give or take, equal sized tasks to carry out.

 

** I doubt that most users of DNG or Raw or Camera JPG for that matter, whether in standard or super-res, give the embedded preview much thought at all. "Why not" - because that would be a lot of calculation to produce something that swiftly becomes redundant so far as the Catalog is concerned. Either straight away a replacement internal preview will be generated, or failing that, the moment the user touches some adjustment this must then happen regardless.

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Community Beginner ,
Mar 16, 2023 Mar 16, 2023

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Thanks for your reply, @richardplondon 

 

quote

Are you certain Enhance is not just copying this low-res preview data from its source? 

 

I have no idea. What would the source be? When I extract the preview from the generated DNG, I see that it represents the edited version of the image, so this rules out the source being the preview embedded in the original CR2.  Is the Enhance function copying one of the previews of the editted source file from its "..Previews.lrdata" folder?  If so, maddeningly it always grabs a low res version from there, even if a 1:1 is available.

 

quote

 

IMO if you are unhappy with how long it would take to Export a super-res JPG, you will equally be unhappy with how long EXTRA it would take to generate one and embed it into the DNG. Whether when that was being originally generated, or during a later Metadata snd Preview update. Those are surely, give or take, equal sized tasks to carry out.

 

I know how long it takes for LR to Export a full res JPEG (a few seconds for me usually), and how long it takes to complete "Update DNG Preview (on the order of 10's of seconds per file).  Because they are extra steps, neither makes me happy.  I would much prefer to know if there is a way to control the size of the Preview that is already being created and embedded in the DNG generated by Enhance.

 

quote

 

** I doubt that most users of DNG or Raw or Camera JPG for that matter, whether in standard or super-res, give the embedded preview much thought at all. "Why not" - because that would be a lot of calculation to produce something that swiftly becomes redundant so far as the Catalog is concerned. Either straight away a replacement internal preview will be generated, or failing that, the moment the user touches some adjustment this must then happen regardless.

 

I had never given it much thought either, until I got excited by the Enhance+SupRes feature, and started producing DNGs. Then I quickly noticed that viewer apps represent the "super resolution" DNG using its wee embedded preview. That was surprising and aggravating.

 

In my case, I do not edit the generated DNG by Enhance, nor do I have any other use for the massive file. My only interest is in obtraining a high quality JPG version of the super resolution, enhanced version of my already edited CR2.

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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@David A. Gilmour , while I am not addressing your specific question, you may have an interest in this thread in the feature request.

https://community.adobe.com/t5/lightroom-classic-ideas/p-enhance-details-as-option-in-export-menu/id...

 

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; ( also laptop Win 11, ver 23H2; LrC 13.3.1,;) 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; Camera OM-D E-M1

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LEGEND ,
Mar 15, 2023 Mar 15, 2023

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As everyone else said just export the file.  The time difference between export and extract is not worth worrying about.  I am sure an "app improvement request" concerning this will be ignored as I doubt anyone else would use this and secondly there is no preview extract built into LrC

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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@Bob Somrak , that is what the outcome is likely to be.

My thought is how does a full size jpeg export compare to a jpeg extracted from a "preview file". 
Preview files are specifically built to display images in the Library Module and I believe they are in Adobe Color space and I am not sure the "Quality" can be adjusted, exported images are rendered from the original images and the Quality and Color space can be selected. See the screen capture.

4E22B854-A490-4C06-A4E9-D597451B9C61.png

 

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; ( also laptop Win 11, ver 23H2; LrC 13.3.1,;) 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; Camera OM-D E-M1

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Community Expert ,
Mar 15, 2023 Mar 15, 2023

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The embedded preview saved within an external DNG file, which is what the OP is discussing, is not necessarily going to be of the same specifications as a LrC preview that's made for Library-module internal pirposes.

 

Regardless, Export can ensure that whatever is most suitable gets made (within a batch workflow). incorporating latest parametric adjustments as well as any output processing.

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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My thought is how does a full size jpeg export compare to a jpeg extracted from a "preview file". 

 

Thanks for your comment @DdeGannes .  You're right that extracting the JPG Preview rather than exporting a JPG means that you're stuck with the choices of "JPEG Quality" and colour space made by the app developers, or perhaps by those who control the relevant DNG file standards.  I can tell you that the JPEGs that I have been extracting from the DNGs produced by the Enhance+SupRes function are in sRGB colour space and appear to be of very high quality with no apparent JPEG artefacts.

 

- David

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Community Beginner ,
Mar 15, 2023 Mar 15, 2023

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As everyone else said just export the file.  The time difference between export and extract is not worth worrying about.  I am sure an "app improvement request" concerning this will be ignored as I doubt anyone else would use this and secondly there is no preview extract built into LrC

 

Thanks for your comments, @Bob Somrak .  

 

Different people have different needs.  In my case, for large projects, being able to go straight from Enhance+SupRes to the full res JPGs that I require would certainly more useful and valuable to me than the alternatives that have been described and that I have tried.

 

My original question was, can this be done?  I have yet to see an answer to that question.  If I see no solutions offered in the next short whil,e, then I will conclude that there is likely no way to force LR Enhance+SupRes to generate a full res embedded preview JPG in the DNGs that it generates, and that a modification to LR would be required to accomplish this.

 

While I acknowledge your certainty that that the community's level of interest would be so low that I will be ignored, I see no harm in raising it in the LR Ideas forum. Who knows, maybe Adobe's decision to generate a low res preview rather than a full res one during Enhance+SupRes processing was an oversight that it will want to correct.  Since LR already provides two ways to force LR to embed full res JPG previews into DNG files (unfortunately neither of those functions is helpful in addressing my need) I am hopeful that the job of adding an preview size selection option to the Enhance+SupRes feature would not be onerous. 

 

While LR does not provide a preview extraction feature, I believe that at least one DAM, Photo Mechanic, does. So Adobe could may some competitve motivation for adding that feature to LR also. 

 

If I post these ideas, yes, they may dangle in the wind ignored.  But perhaps they will spur the development team to investigate and to act.  I'm inclined to make the request rather than give up without trying.

 

-David

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LEGEND ,
Mar 15, 2023 Mar 15, 2023

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Actually, Adobe provides a preview extraction script you can download and install in LrC

 

https://helpx.adobe.com/lightroom-classic/kb/extract-previews-for-lost-images-lightroom.html

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Community Expert ,
Mar 16, 2023 Mar 16, 2023

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Actually, Adobe provides a preview extraction script you can download and install in LrC

 

https://helpx.adobe.com/lightroom-classic/kb/extract-previews-for-lost-images-lightroom.html


By @Bob Somrak

 

This targets a different "preview" - the ones in the catalogue preview folders. The OP is talking about previews embedded in the DNG.

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LEGEND ,
Mar 16, 2023 Mar 16, 2023

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Community Beginner ,
Mar 16, 2023 Mar 16, 2023

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Actually, Adobe provides a preview extraction script you can download and install in LrC

 

https://helpx.adobe.com/lightroom-classic/kb/extract-previews-for-lost-images-lightroom.html

This targets a different "preview" - the ones in the catalogue preview folders. The OP is talking about previews embedded in the DNG.

 

That was my first reaction too, @john beardsworth, although on reflection I am wondering if @Bob Somrak has hit on a good workaround. I am not sure what "..Previews.lrdata"-type previews LR creates as the Enhance+SupRes function generates a DNG. If a full res JPEG is immediately available among that internal set of previews, is extracting it the shortcut that I have been looking for?  I will test the idea.

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Community Expert ,
Mar 16, 2023 Mar 16, 2023

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Different people have different needs.  In my case, for large projects, being able to go straight from Enhance+SupRes to the full res JPGs that I require would certainly more useful and valuable to me than the alternatives that have been described and that I have tried.

 

My original question was, can this be done?  I have yet to see an answer to that question.  If I see no solutions offered in the next short whil,e, then I will conclude that there is likely no way to force LR Enhance+SupRes to generate a full res embedded preview JPG in the DNGs that it generates, and that a modification to LR would be required to accomplish this

 

You do have quite a fixation with using an external app to get these full res JPEGs! You already have an answer - instead of rebuilding the DNG preview and then using a 3rd party app, simply export.

I don't think there's any way to generate a full res preview automatically, and that is a shame as I get fed up of camera manufacturers or software developers making arbitrary choices about embedded preview sizes rather than defaulting to full size. But for the workflow you've described, I've given you a one step solution that remains entirely within LR and doesn't require some third party app. So I wouldn't hold out much hope if you only based this feature request on using a third party app for something LR does perfectly well.

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Community Expert ,
Mar 16, 2023 Mar 16, 2023

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An analogy comes to mind - you have a choice of how to get to city A: you can drive directly there in about an hour. Not a very interesting journey, nothing special.

 

OR you can drive in the opposite direction, to city B's airport (this takes about an hour), from where you can catch a jet flight to city A. This way you can benefit from the fastest means of transport available - fully ten times the speed of your car. But is it the better journey, taken overall?

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Community Beginner ,
Mar 16, 2023 Mar 16, 2023

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You do have quite a fixation with using an external app to get these full res JPEGs! You already have an answer - instead of rebuilding the DNG preview and then using a 3rd party app, simply export.

I don't think there's any way to generate a full res preview automatically, and that is a shame as I get fed up of camera manufacturers or software developers making arbitrary choices about embedded preview sizes rather than defaulting to full size. But for the workflow you've described, I've given you a one step solution that remains entirely within LR and doesn't require some third party app. So I wouldn't hold out much hope if you only based this feature request on using a third party app for something LR does perfectly well.

 

Thanks, @john beardsworth.  A former employer called my fixations persistence. I prefer tenacity.

 

If I cannot find a way to force Enhance+SupRes to embed a full size preview, then yes, Exporting a full res JPG is the only way for me to go. That is, while I wait to see if I can stir any interest on Adobe's part in addressing the strange situation of its Enhance + Super Resolution process embedding a low res preview rather than one of matching resolution in the generated DNG.

 

It is unfortunate that, whether or not Adobe makes this change, a 3rd party tool is still currently required to extract the previews from RAW/DNG files. Sometimes 3rd party tools are all we have when a developer leaves functional holes in their application. For years, I have been using your Big Note and ListView plugins, along with a few other choice LR plugins. I don't suppose that you would like to write one for extracting the preview from a DNG? 😉

 

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Community Expert ,
Mar 16, 2023 Mar 16, 2023

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Ha ha! I could, and am pretty sure I do have one based on Exiftool somewhere. But my plugins tend to focus on things you can't do perfectly well in LR.

 

It's also worth adding that - as you may know - one of the benefits of DNG is that its embedded previews do allow you to create pixel-perfect renditions of the photo including your editing work, even if the editing application is no longer available.

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Community Expert ,
Mar 16, 2023 Mar 16, 2023

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Yes indeed an embedded full-res preview in tbe DNG may lend some futureproofing. If that is to reflect Catalog editing, that would be a question of subsequent DNG update, not initial creation. But in this instance the OP wants a super-res DNG only to get a JPG from - after which, it would be deleted from disk. For that purpose, an ability to export a super-res processed JPG directly from the original resolution Raw instead, plus edits, would seem to be the most efficient option of all. Were that available.

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