Corrupt DNG?

Hello hivemind...

I was working on my LR catalog and I found an image that had a black exclamation mark saying that LR had problems reading this photo... I tried opening it in PS CC2014 and it says the file format module cannot open the file. I have the latest version of ACR on my machine. The Win10 picture app can "open" it as well as FastStone Viewer 6.8. However, it is my opinion that these apps only read the preview embedded in the file. Can anyone confirm or deny? I think that perhaps some of the metadata might be hosed up... Does anyone have any suggestions regarding recovery efforts for the DNG? It doesn't appear that any other files are having the same issue as the images are on a RAID array which also checks out. I no longer have the CR2 because the image is from mid 2016ish. I can share the DNG if anyone is interested in trying it themselves. That said, I would not be heartbroken if it was lost... I am just a sucker for digging in since I am fairly technical... I saw there is a project on GitHub that parses DNGs... I may play with that..

Thanks in advance!

I believe I have answered my own question. I used another RAW file reader which returned very little information leading me to believe a) the RAW file is corrupt and b) that FastStone and Windows just use the embedded jpeg in the file to return the image when compared against a known good DNG file. For anyone one that is interested, I used an application called RAWDigger which has a free trial license... I guess this image is toast...

Thanks!

Is it an out of camera DNG? Or did you convert it to DNG from another RAW format? If it was converted you could simply go back to the original file and create a new DNG conversion. Personally I don't see a lot of point in converting from a native format to DNG unless you need it for software compatibility issues, or you are using the RAW panoramic stitching or HDR modules. Either way I would always archive the original files, along with backups. I always try to make sure that I have at least two copies of every original image file, everything else can be rebuilt as long as you have those original files backed up.

Alan

There are a few ways to validate a DNG, the general gist being described here:

https://dpbestflow.org …validation/dng-validation

You can usually do this with Lightroom or Bridge, which it sounds like you are essentially doing now.

If you download the Adobe DNG SDK:

https://www.adobe.com …ownloads/dng/dn​g_sdk.html

there is a utility called "dng_validate" that will also perform these tasks.

If worse comes to worse and you cannot validate the DNG, you may be able to extract the embedded JPEG from it with dcraw, using the command:

dcraw -e filename.DNG

Thanks for the reply... No, it was a conversion from a CR2 which is long gone. In 14 years, this is my first corruption of a RAW file. I think that's a pretty good track record for my storage array in spite of it being long in the tooth. Though, it concerns me that it's starting may be starting now and I have received no warnings from the array manager. The other possibility is that it's been this way for years and I have just never noticed. Since the image is unimportant based on the preview jpeg, I feel no remorse deleting from my catalog. I am currently checking the entire catalog as I have already checked the array. Such is life.

Thanks!

Thank you for the reply... Yes, I was thinking of going down that route as a third or fourth measure but I guess I decided I don't need to put too much time/effort into an image I don't quite care about. Also, the RAWDigger uses the Adobe SDK for DNG parsing/enumeration so I feel somewhat validated when that application didn't work either. I don't need to extract the jpeg preview from the DNG because I have a full sized processed JPEG on Flickr of the image. Not as a backup but as something that I presented to the person. I can download it and replace the DNG in my collection for historical purposes.

Thanks!

I wrote a little program to help with this about five years ago. Not sure if it'll still work, but in short it's not difficult to validate a DNG file

https://photography-on-the.net …/showthread.php​?t=1391986

Thanks... I will take a look!