Jpegs converted to DNG in Lightroom 4 show as "Digital Negative / Lossy Compressed"

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Hi,

I always convert my jpeg files to DNG format and this worked fine in Lightroom 3 but now that I am using Lightroom 4 my jpegs are converting to "Digital Negative / Lossy Compressed", at least according to the Metadata filter for file type. All my jpegs previously converted to DNG lossless under Lightroom 3. Why are they now converting to lossy? I do not have the "Use Lossy Compression" setting ticked when I convert. If I continue to use Lightroom 4 to convert, will my lossy files be inferior to the Lightroom 3 lossless conversions?

Thanks,
Adam.
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Adam Hall

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Posted 6 years ago

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marcos souza

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Sorry, but why convert JPEG in RAW? Once cooked carrots cannot be raw again!
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Rob Cole

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DNG does not imply raw, necessarily, just like NEF does not imply raw necessarily (you can save a jpeg in a NEF file via NX2, just like you export a jpeg as DNG in Lightroom). Still, it does beg the question of why wrap a jpeg in a DNG. There was a thread about this recently, but in a nutshell:

Lr edited jpegs will not show edits outside Lr, whereas DNG-wrapped jpegs, will (via embedded preview), so it actually makes some sense to wrap jpeg masters with DNG, in Lightroom, then export without the wrapper (since Lr changes are baked in at that point).

And for the sake of completeness: - the reason to wrap jpegs in a nef is for non-destructive editing support in nx2.
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Rob Cole

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The only way I've found to tell the difference between a raw converted to lossy dng and a jpeg converted to a (no additional loss) dng is by the "original raw file name" in the metadata panel, on a photo-by-photo basis (or by checking white balance & camera profile in develop module...).

But if it says "lossy compressed", it means the image data is in jpeg format, whether it maintains editing characteristics of original raw, or was a jpeg to start with...

UPDATE: I have added a feature request for distinguishing metadata:

http://feedback.photoshop.com/photosh...

UPDATE #2: You can distinguish between DNG-wrapped jpegs and lossy-compressed DNGs of original raws by looking at the camera profile - wrapped jpegs will always be "embedded". Granted, you'll need DevMeta or AnyFilter or some such thing to do this. Without one of the aforementioned, you may be able to look at camera-model or lens-data etc to distinguish, but I'm not sure if that's 100% reliable.
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Rob Cole

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|> " If I continue to use Lightroom 4 to convert, will my lossy files be inferior to the Lightroom 3 lossless conversions? "

To answer your original question more specifically:

No - you will not lose quality when converting jpegs to DNG in Lr4 - same unaltered jpeg image data, just different metadata handling...
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Adam Hall

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Hi Rob,

Thanks for your help with this - good to know that Lightroom 4 is only describing them as lossy because the original sources were jpegs, which of course were already compressed. Hopefully the programmers will be able to update the metadata for the older jpeg-to-DNG conversions too so they won't say lossless.

Cheers,
Adam.
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Rob Cole

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|> "Hopefully the programmers will be able to update the metadata for the older jpeg-to-DNG conversions too so they won't say lossless."

+1 vote.