DNG downsampling

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Part of my job is to weed through thousands of photos and pull up the few hundred that I deliver. Still, I have chosen to keep around what I've shot just in case, maybe a year from now, my clients have some weird request for some photo that wasn't important today. For this case (which has come up many times), I use DNG Converter to downsize my raw files from 24MP to 6MP to save storage space. I would like this to be built into LR so that I can select files and have them remain in the catalog but be down-converted. I'd like Adobe to give me the best possible method... maybe a 4:1 which would reduce issues? 24->6MP or 32->8MP or some 4:1 binning.  
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seanhoyt-dot-art

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Posted 2 years ago

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Photo of Victoria Bampton - Lightroom Queen

Victoria Bampton - Lightroom Queen, Champion

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How small do they need to be? Have you tried converting to lossy dng at their original size?
(Edited)
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seanhoyt-dot-art

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I frequently take a 100GB set down to 5GB. Lossy full size will give me 25GB. 
(Edited)
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Victoria Bampton - Lightroom Queen, Champion

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Makes sense. Ok, try this:

1. Put all the photos you want to downsize in a new collection.
2. Select them all and go to Export. Set "Add to Catalog" at the top, then set the DNG size and lossy compression further down. Hit Export.
3. Delete the photos in the first collection ONCE THE EXPORT COMPLETES.

The downsized photos will now be in the catalog. They won't be in collections, have flags, and they won't have any VC's or other information that's not stored in XMP. 

It's not exactly what you're asking for, but this same request was heavily debated when lossy DNG was introduced, and the decision at the time was they didn't want to make it too easy to throw away originals, due to the number of unsuspecting users who would do it by accident.
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seanhoyt-dot-art

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I appreciate your replies here. Yeah, I did see Tom's reply 5 years ago about this export method. That will actually save time versus using the external DNG converter. Thanks! 

IDK, the same (unsuspecting user) argument could be used for those that execute a lossy DNG convert and toss out 3/4 of their data along with originals using the dialog. Or those that backspace on a set of images and click to delete them from disk vs remove from cat. I'm much in favor of putting ownership onto the user given the correct dialog warnings. They could also help here with file locking (or in LR, mark as "final"). 
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seanhoyt-dot-art

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Export 'kinda' works. You totally lose file structure :(
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Victoria Bampton - Lightroom Queen, Champion

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Ah, I assumed they were all in one folder. There's a plug-in or two that can export to a matching folder structure, which might help. http://photographers-toolbox.com/products/lrtreeexporter.php
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seanhoyt-dot-art

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For the second part of my question, I'm wondering if there's value in the 4:1 pixel bin. There is currently no real downsample option that does not require interpolation and other complexities. Why not bin it then compress it? 
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Victoria Bampton - Lightroom Queen, Champion

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That I'll have to leave to an engineer (and you might want to put it as a "reply" so it's more visible)
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Just Shot Me

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Ah there is a DNG converter built into LR. Library module Library menu item Convert Photo to DNG.
There are many option available in the dialog box.

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Victoria Bampton - Lightroom Queen, Champion

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Very true, but that doesn't allow downsampling, which is the feature the OP is requesting. Reducing the pixel dimensions at the same time as conversion is only available in the Export dialog, currently by design.
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Just Shot Me

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So what the OP needs is that down sample option included into the LR DNG converter.
Photo of Victoria Bampton - Lightroom Queen

Victoria Bampton - Lightroom Queen, Champion

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Yup, you've got it. But there was a lot of pushback against that idea when lossy DNG's were introduced. Of course there are new engineers on the team now, so it might swing the other way.