JPEG XL revisited

[suttonbg]

Dear Mario,

I'm writing (again) to seek your advice (again). This post roughly follows on from the thread started by jch2103 on Nov 10, 2022.

Today I found that panorama or HDR images I had generated with Adobe Camera Raw and saved as DNGs (the only option) would not show thumbnails in iMatch ("Nothing to show for this file") and would not open in File Explorer or Photos on my Windows 10 machine (error message: unsupported file type). It seems to affect only images generated since about November 2023 and is not a problem for DNG files generated from single RAW files edited in ACR.

A useful hour long chat session with Adobe Support revealed that recent versions of ACR were using the JPEG XL rather than the original JPEG codec for the embedded preview image. A work-around they suggested, which works, is to save the images with compatibility set to an older ACR version, such as 12.4.

I wondered if Microsoft had released a WIC codec for this format, but a Google search lead to complete confusion. However, I noticed that in a post by deaded on Oct 5, 2023, his WIC listing includes
" Codec 'Microsoft JPEG-XL Decoder' (Vendor: F0E749CA-EDEF-4589-A73A-EE0E626A2A2B) for extensions .JXL"
so that made me wonder if, indeed, such a codec existed and could be loaded. If you have any knowledge about this, I would appreciate it. My own WIC diagnostics lists no such codec.

I note all the points you raised in your earlier posting why this might be an orphan format, but if Adobe and Microsoft start using it,... If it would be of any value to you, I would be happy to provide samples of DNG files which do and do not provide functional previews and thumbnails in iMatch, as I have it set up, at least.

Kind regards
 

[ubacher]

This problem started since Adobe started using DNG Version 1.7 which uses the jpeg xl coding inside the dng (so I understand)
When I generate a stitched panorama in ACR the dng it outputs is such.
There are no codecs for this new version of dng yet.
Similarly for JPEG XL, which camera raw can also output now. No codec yet.
I just found that irfanview can display it.

And .HDR files have the same problem - no codec.

( I was just today googling and testing about these formats!)

[Mario]

If neither Windows WIC nor LibRAW support your special Adobe-only DNG variant, you'll have to wait until they do.

I wondered if Microsoft had released a WIC codec for this form

Microsoft distributes updates to WIC as part of the regular Windows updates.
LibRaw occasionally publishes new "official" releases (not beta version) I then include in IMatch.

If DNG slowly becomes yet another of the ever-changing, proprietary RAW formats it was designed to replace, we're in trouble.
Adobe has changed DNG many times over the years, whenever they needed something for one of their products.
Usually breaking perfectly fine workflows, Windows WIC codec support, LibRaw support and other software in that process.
But, hey, Adobe! They're like Apple. They do what they want and their customers have to eat it.

I don't want to support yet another 3rd party image library like the Adobe DNG SDK. I already support 3rd party image, video and audio libraries, Windows WIC and LibRaw.
My lifetime is limited. And making oneself more dependent on Adobe is a bad idea, IMHO.

If Adobe wants to change DNG all the time, they should provide a DNG WIC codec again. They did years ago, but stopped support for it for unknown reasons. Or they should let Microsoft know in advance so Windows can ship an updated DNG codec that handles whatever Adobe has come up with.

[Mario]

I've had a look at the ADOBE DNG SDK (Software Development Kit).
And I could even compile their sample DNG Validator.

Unfortunately, it seems Adobe does not publish any documentation or examples or a guide for how to use the Adobe DNG SDK.
At least I could not find anything, not even a tiny piece of code that shows how to load a DNG, extract the preview in any format.
This puts pretty much a stop to this route.

Reverse-engineering how to use the hundreds of functions in the SDK to read DNG files in IMatch without WIC codecs or LibRaw could take a very loooooong time.
Best to wait until Microsoft and LibRaw catch up with the latest changes Adobe did do the DNG format.

[Carlo Didier]

Today I found that panorama or HDR images I had generated with Adobe Camera Raw and saved as DNGs (the only option) 
 

You can also save a copy from ACR as a TIFF image. That's what I do. Still have to then manually delete the DNG if I don't want to keep it.