I'm apparently entitled to unlimited storage with Amazon (Prime Photos) and I've uploaded all my DNG images (about 20GB) to their "cloud". When I view them online, they are tiny. Apparently that's because when you upload DNGs, Amazon displays the embedded JPEG preview.

What's the proper way to regenerate all the previews (preferably with my corrections) in Lightroom 3? I found some guides that appeared to do something, but from what Exiftool is telling me, the original camera previews are still being used. These are small and totally not color-corrected.

For what it's worth, the photos were originally imported with Pentax's RAW format and I later converted them to DNG, not sure if that's what's preventing the re-creation of the previews or not.


To regenerate the embedded DNG preview for an image, right-click on the image, choose Metadata, then choose Update DNG Preview & Metadata.

I use this process to ensure that the thumbnails that Windows Explorer displays for DNGs reflects the changes I have made to the image in LR, so I believe it should do what you want.

If you want to do this for multiple images, simply ensure you have selected all the images in the Library module for which you want to regenerate the previews.

Caveat: this is valid in LR6, and while it has been a while since I was running LR3, I have no reason to believe it would not be the same in LR3.

  • That sure seems like it should do it, but no luck. I have previews set to full size, found the menu item you mentioned and chose "Update DNG Preview & Metadata". LR was obviously doing something, pegged the CPU for a good 20 minutes. But previews were not full size (that I can tell - Finder shows maybe 400px wide), and even worse, did not seem to include edits.
    – sporker
    Jan 30 '17 at 0:02

In the current lightroom if you just convert to DNG again, it will redo the DNG from the one there, and change preview size. I cannot say in Lightroom 3, that is very old, and I do not have a copy any longer. There is also a Metadata Preview rebuild option, but I do not see (in the current version) that it permits changing the size. I do not know if that retains the existing size, or Lightroom's default size is used, but you might try that as well.

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