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Extracting Full Size JPEG Preview From Enhanced Super Resolution DNG

Forum|Forum|2 years ago
March 15, 2023
7 replies
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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

Windows

This topic has been closed for replies.

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richardplondon

Community Expert

Out of interest, I have just done an empirical test - using as input an older file from a camera (Pentax K10D) producing technically good Raw but of limited resolution: AFAICT the use case where super-resolution is going to be of the most practical benefit day to day.

I took that processed and cropped Raw and:

A - made a plain JPG export, quality 90, no resizing, no output sharpening.

B - same, except with resizing set to to double the (as cropped) pixel dimensions.

C - same (doubled resolution), adding output sharpening set to Screen, Low.

Then I also made an Enhance+SuperRes DNG and exported that to JPG:

D - quality 90, no resizing, no output sharpening.

AND... compared. To my eyes, with the particular image chosen, D is slightly nicer than C but it is very very subtle and would not I think be apparent except in a close side by side comparison. B is a little softer looking than D but I can't really point to any pixel feature that is present in D and not present in B.

Perhaps this suggests the most efficient option so far? No creation of an enhanced DNG in the first place. Just a reasonably good visual assessment of the Raw file concerned - like a virtual 200% zoom, let's say - as exported directly from that Raw.

David A. GilmourAuthor

Participating Frequently

Interesting, @richardplondon. I have been impressed by the extra detail that I perceive in the images that Enhance+SupRes and its AI magically produce, especially from my older CRW files. Those observations were very casual though. I have not taken your more methodical comparative approach. I will try some testing along the lines that you suggest, using a selection of my RAW files.

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richardplondon

Community Expert

Again, just for interest and a purely indicative sample. I can imagine Enhance making more of an obvious difference with some kinds of subject matter, or zero difference in other cases.

As I say, I don't see any differences of content, more of presentation - Enhance is magical but not actual magic - but notably, the treatment of dark / light sharpening 'halo' along edges. Of course the original's sharpening did not have doubled scaling in mind.

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hanomann

Known Participant

What are you doing with the super resolution jpg? Remember it is only 8 bit.

David A. GilmourAuthor

Participating Frequently

What are you doing with the super resolution jpg? Remember it is only 8 bit.

By @hanomann

I do various things with those super resolution JPGs, but this is the primary one.

I use iMatch as my digital asset manager. When I use iMatch to view the Canon RAW files in my archives, its 'Visual Proxy' feature enables me to see the edited, enhanced, super resolution version of those images, rather than the untouched original exposure that I would otherwise see. There is a setting within iMatch where you can establish a simple universal rule that associates your RAW files with their visual proxies.

There is more information on this feature of iMatch here: https://www.photools.com/help/imatch/rel_versions.htm?dl=h-38

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hanomann

Known Participant

At the end of your workflow you have the orignal Canon Raw file, an enhanced jpeg and in the Lightroom catalog the processing receipt as the product of your workflow within Lightroom, right? What are the advantages of iMatch that let you prefer to use two dam programs?

Bob Somrak

Legend

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

M4 Pro Mac Mini. 48GB

DdeGannes

Community Expert

@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.

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; (also Laptop Win 11, ver 24H2, LrC 15.0.1, PS 27.0; ) Camera Oly OM-D E-M1.

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richardplondon

Community Expert

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.

DdeGannes

Community Expert

@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/idi-p/13643372

Regards, Denis: iMac 27” mid-2015, macOS 11.7.10 Big Sur; 2TB SSD, 24 GB Ram, GPU 2 GB; LrC 12.5,; Lr 6.5, PS 24.7,; ACR 15.5,; (also Laptop Win 11, ver 24H2, LrC 15.0.1, PS 27.0; ) Camera Oly OM-D E-M1.

GoldingD

Legend

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

David A. GilmourAuthor

Participating Frequently

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

john beardsworth

Community Expert

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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richardplondon

Community Expert

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.

David A. GilmourAuthor

Participating Frequently

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

-David

David A. GilmourAuthor

Participating Frequently

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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