DNG 1.7 lossy: unable to open embedded preview

[xnview]

Exactly. Below is screenshot of what I see when opening that file. If you open the DNG 1.4 version (_MG_5078.c7.dng) you see that it opens full size preview but the DNG 1.7 version does not although full size JXL preview is inside the file as you can confirm e.g. with extracting previews with exiftool.

i have not that. Could you try 'update catalog from files'? windows?

[golemus]

Exactly. Below is screenshot of what I see when opening that file. If you open the DNG 1.4 version (_MG_5078.c7.dng) you see that it opens full size preview but the DNG 1.7 version does not although full size JXL preview is inside the file as you can confirm e.g. with extracting previews with exiftool.

i have not that. Could you try 'update catalog from files'? windows?

Yes, windows 11.

I tried it but it did nothing. I also disabled catalog completely and the issue remained.

Worth noting is that I use typically viewer window instead of the preview window in browser.

[xnview]

I tried it but it did nothing. I also disabled catalog completely and the issue remained.

you need to change to half/full in settings>Read>RAW>View

[golemus]

I tried it but it did nothing. I also disabled catalog completely and the issue remained.

you need to change to half/full in settings>Read>RAW>View

I know that rendering of RAW DNG 1.7 data works now (although there are still color rendering issues which I think I might have mentioned in different topic). But this topic was meant to be report of issue with "embedded preview" feature. Title of topic was maybe a bit unclear but I now changed it from "preview" to "embedded preview".

I guess purpose of embedded preview is to be able to browse photos fast through, if you enable half or full it reduces browsing performance significantly why I tend not to use it unless there is some special case need. There is a full size .JXL file inside a DNG 1.7 lossy file which I think I mentioned already and it appears to not be rendered at all.

[xnview]

I guess purpose of embedded preview is to be able to browse photos fast through, if you enable half or full it reduces browsing performance significantly why I tend not to use it unless there is some special case need. There is a full size .JXL file inside a DNG 1.7 lossy file which I think I mentioned already and it appears to not be rendered at all.

So preview is good, right?
And you would like to use jxl too for thumbnail?

[golemus]

I guess purpose of embedded preview is to be able to browse photos fast through, if you enable half or full it reduces browsing performance significantly why I tend not to use it unless there is some special case need. There is a full size .JXL file inside a DNG 1.7 lossy file which I think I mentioned already and it appears to not be rendered at all.

So preview is good, right?
And you would like to use jxl too for thumbnail?

Could you be more specific what you mean?

1. Rendering of RAW data of DNG 1.7 lossy files seem to work OK except of issues with color space.

2. Rendering of JXL embedded preview of DNG 1.7 lossy files does not appear to work at all.



Of those I mainly use 2. because it is so much faster to open and browse through. Especially if there is lets say 300 DNG lossy images in a folder with no titles and you are searching for specific image. Or trying to decide which of the images to delete and which to keep. It would take ages to do this if you had 1. turned on. I am not claiming that performance is bad but IMO it is like that also in other apps such as Faststone or Windows Photo.

I'd use 1. only if there is need for process the DNG file.

e.g. for the file you already mentioned _MG_5078.10m.ly.dng, I extracted to same shared folder its previews. It contains this 468 KB .JXL file which XNMP seems to be unable to use for embedded preview:

https://nx76363.your-storageshare.de/s/ZDGWGsKxK3RzxZb

Instead it uses wrong file as source for embedded preview function, this 9 KB .JPG file which is also inside the DNG file:

https://nx76363.your-storageshare.de/s/TXJBcM7F3n2sT77

[golemus]

My Nextcloud seems to have temporary issue, if the links dont work you can extract the same JXL file from lossy dng with this command:

exiftool -preview:subifd2:previewjxl -b -W %%d\%%f-EMBX%%-c.%%s "%IFILE%"

[golemus]

Worth noting I am now only referring to what is rendered inside A. ViewerWindow.

I am not taking any stand on how the file should be visible in B. BrowserWindow or C. BrowserWindow-Preview or D. BrowserWindow-thumbnails. Or don't have knowledge how DNG 1.7. lossy files should work with Catalog or thumbnail caching.


I have not yet tested functionality with DNG 1.7 in B, C or D as I use most of time A.

[golemus]

I rewrote bug report in 1st post a bit more specifically that it should be reproduced inside ViewerWindow.

[golemus]

In case my nextcloud is offline when you are next time online I also put the files to wetransfer. it has all preview files extracted with exiftool from both DNG17-lossy and DNG14-lossless (both done with adobe DNG tool)

Link:

https://we.tl/t-DoF1wHJRKYt1L3ez

[golemus]

This is what Libraw dev said about the issue:

> To enable JPEG-XL previews please set LIBRAW_RAWOPTIONS_ALLOW_JPEGXL_PREVIEWS bit in imgdata.rawparams.options
> (not all apps/callers supports JPEG-XL, so it need to be enable explicitly)
> LibRaw uses largest (enabled) preview in unpack_thumb.
> Also one may use unpack_thumb_ex(N) to extract Nth thumbnail from thumb_list

[golemus]

.

My Nextcloud had an issue but the shares above should be working again.

[golemus]

This bug is still present in 1.12.2