DNG Convert Thumbnail JPGs

[Michael23287264zq69]

I've been trying to convert RAW images (CR2, CR3, NEF) to DNG using the lastest version of Adobe DNG Converter (as well as Adobe Bridge when that didn't work).  The DNGs appear to be just fine on my desktop, but when I ingest them into our DAM the images provide a strange thumbnail – often with a higher contrast and yellow tint.  Almost looks like film from the 80s.

We initially thought it was our DAM, but upon further inspection my engineer tells me our DNG files seem to be neglecting a thumbnail preview in spite of us setting it to Full Size in the converter.

Either something is wrong with the converter or my engineer is missing something.  Is there someone who I can work with who can help troubleshoot this with me?  Maybe at the very least review one of my converted files and tell me if a full-sized thumbnail JPG is held within it?

Running MacOS Monterey 12.2.1 on a 2017 iMac Pro.

[TheDigitalDog]

Have your people gone through this:

https://www.adobe.com/content/dam/acom/en/products/photoshop/pdfs/dng_spec_1.4.0.0.pdf

Have you tried using Lightroom Classic to convert and what settings are you selecting for the conversions to DNG.

There are Adobe folks who occasionally lurk here, if you don’t hear from anyone, PM me and I'll try to at least get a name of someone inside Adobe you might contact.

You can supply a DNG via something like Dropbox for others to review. Just provide a URL to the public folder.

[Michael23287264zq69]

Thank you so much!

[Rikk Flohr: Photography]

We'd love to obtain a sample DNG for review by the engineers. Would you be able to provide a file to us?

[Michael23287264zq69]

Thank you, Rikk!  I just sent you a PM with a link to the file as well as some screenshots for reference.  I greatly appreciate your help.

[Rikk Flohr: Photography]

I have the files and will forward to engineering for review. I will respond on this thread once they've given me a report. 

[Rikk Flohr: Photography]

Thank you for the files. We've reviewed the information and find that the DNG appears to be correct and have accurate previews. At this point we are leaning towards a problem with your other DAM Software. We recommend your filing a bug with them and include the same data you provided to us. 

Comments from the engineer: "The DNG also contains “raw previews” (i.e., making it a Smart Preview as well) and I’m guessing that the DAM software is trying to read that preview instead of the normal JPEG-based ones.  To test this theory, the customer can try re-exporting the DNG without “fast load data” embedded and check if the same issue results in the DAM software."

I hope this helps. 

[Michael23287264zq69]

Rikk,

First and foremost, thank you so much for all your help.  Please extend my thanks to the engineers taking the time to look into this matter for us as well.  I greatly appreciate the assist.

I tried re-exporting the DNG without the Fast Load Data option being checked and still got the same yellow tint color balance issue in the thumbnail shown within our DAM.  Does that mean it confirms your engineer's suspicions that the issue is tied to the DAM trying to read a Smart Preview versus the JPG-based one?  If it helps by giving context, the DAM we are using is Open Text Media Manager.

Also, one other question regarding DNG JPG previews as a whole – are any adjustments made to the DNG like contrast or brightness, etc. reflected in the JPG preview?  In other words, if someone makes an adjustment, does the DNG file then replace the JPG, or is that JPG always going to be of the original, un-adjusted asset?  Sorry if that's a entry-level kind of question.  Still getting myself familiar with the format.

[TheDigitalDog]

You may want to check this out. Old but still a good read:

https://www.dpbestflow.org/dng

One of the most useful features of DNG is the ability to embed a preview in the file that displays the image after you have made your adjustments. This is particularly helpful if you need to look at the file with software other than that with which you made the adjustments. This is particularly valuable for third-party DAM software. In these cases, it’s helpful to have a large embedded JPEG preview in the DNG. It makes the file a bit larger, but it’s extremely useful.

[Rikk Flohr: Photography]

" Does that mean it confirms your engineer's suspicions that the issue is tied to the DAM trying to read a Smart Preview versus the JPG-based one? "

Yes. 

thedigitaldog's link provided is a good place to go for information.