P: Regarding JXL Compression in derived Merge/Enhance DNG Images

[tigre58]

Why with LR CC v.13, the files panorama files are now saved as lossy files?

[Rikk Flohr: Photography]

The compression method for derived DNGs has been changed from JPEG to JPEG-XL, which provides a smaller data footprint without loss of quality. 

Creating a merged DNG such as a panorama is already a “lossy” process because the merged pixel data has been demosaiced, aligned, and blended from the original photos.  Using JPEG XL compression makes a much smaller visual change.

[tigre58]

But , in previous versions of LR CC,  panorama files were saved as lossless files. Is posible change this set before making a panorama?

[Rikk Flohr: Photography]

See additional comments added above. 

[JohanElzenga · Accepted solution]

But , in previous versions of LR CC,  panorama files were saved as lossless files. Is posible change this set before making a panorama?

By @tigre58

Do not look at the words 'lossy' and 'lossless', look at your image and see if there is any visible effect of this new compression method. Recreate an older panorama and compare the old massive DNG with the new, much smaller DNG. Do you have any reason to be concerned?

[ClintGryke]

I just noticed this change today and came across this thread in search of the answer which is neatly provided thanks. However, it does raise a couple of questions. This may be pretty pedantic but it would be really interesting to know what the experts think.

So I've been experimenting with the new HDR Edit and Export feature in Lightroom. I have an Apple  XDR monitor which I have been using for HDR video up to now but this ability to edit and export stills in XDR is very exciting. In fact this is how I realised the Merge to HDR DNG file had changed as I was doing a HDR merge to test the HDR editing in Lightroom Develop Module.  Now in the guidance from Adobe (Edit and Export in HDR), it recommends using JPEG XL or AVIF files for export for sharing and web galleries and TIFF or PSD where additional HDR work is required.  The implication here is that the lossy compression of the merged DNG file is of no noticeable importance if not doing further editing but it may well be important if doing further editing.

So my question is in the case of merged DNG files, is there any point in exporting as lossless TIFF or PSD as against JPEG XL? In other words, is the data already lost in the same way as it would be if exporting an 8-Bit JPEG originally derived from a raw file for example as a TIFF or PSD? There is a huge difference in the file sizes for sure. My main usage at the moment would be importing into Final Cut Pro and some editing may be needed there to color match my HDR video.

[JohanElzenga]

Yes, the data are lost. The fundamental difference between lossless compression and lossy compression is that in lossless compression the decompressed image is bit for bit identical to the original. In lossy compression that is not the case. The decompressed file will not be absolutely identical to the original file. Whether that leads to any practical and visible differences is another matter that I cannot answer. My own suggestion is always that the proof of the pudding is in the eating, not in reading the recipe. Try it yourself.

[ClintGryke]

Sure - I can't see any difference from detailed examination of a few DNG files derived from the older and new processes. Perhaps with further editing? 

[reproo2773183]

The compression method for derived DNGs has been changed from JPEG to JPEG-XL, which provides a smaller data footprint without loss of quality. 

Creating a merged DNG such as a panorama is already a “lossy” process because the merged pixel data has been demosaiced, aligned, and blended from the original photos.  Using JPEG XL compression makes a much smaller visual change.

By @Rikk Flohr: Photography

Are you saying that previously a merged DNG Pano used an older JPEG encoding that supported 16bit?

[Rikk Flohr: Photography]

"The compression method for derived DNGs has been changed from JPEG to JPEG-XL, which provides a smaller data footprint without loss of quality. "

"Are you saying that previously a merged DNG Pano used an older JPEG encoding that supported 16bit?"
That appears to be exactly what was said. 

[reproo2773183]

Thanks Rikk, Crystal clear now 🙂

Panorama Merge in Photoshop then saved as Layered PSD, completely avoids Lossy compression? or same as the old Lightroom?

[JohanElzenga]

Panorama merge in Photoshop saved as layers is completely different. The compression depends on how (which file format and which compression) you decide to save it.

[reproo2773183]

Up to 5 minutes ago I thought that was the case :), not so sure anymore.

[JohanElzenga]

Up to 5 minutes ago I thought that was the case :), not so sure anymore.

By @reproo2773183

Why? You are comparing apples and not even oranges, but potatoes. Panorama merge in Lightroom creates a DNG that is auto saved. Panorama merge in Photoshop is done with RGB images rather than raw images, and there is no auto save to any mandatory file format. You choose the file format and the compression.

[reproo2773183]

love the anology.

in French

Pourquoi? Vous comparez des pommes et même pas des oranges, mais des pommes de terre.

So might be closer than you assume. 🙂 LOL

[ACEkin]

I knew something must have changed in DNG files not because I detected quality loss but because I lost the ability to view them in external viewers. Viewing DNG panoramas in Windows File Explorer, FastStone, or XNView image viewers has become impossible. Is there a workaround to be able to browse folders and see these files? Out of curiosity, does "lossy" DNG compression still maintain the color space and 16-bit image information?

[Olaf314551382lie]

Ich habe Lightroom Classic Version 13.0.1 und Camera Raw 16.0 auf meinem neuen Rechner installiert.

Seitdem bekomme ich VERLUSTREICH komprimierte Panoramen und HDRs mit deutlich reduzierter Auflösung und Dateigröße (Dateityp "Digitales Negativ/Verlustreich komprimiert". Ich möchte jedoch verlustfreie DNG-Dateien erzeugen.

Mache ich etwas falsch oder haben andere das gleiche Problem? Anwendungsfehler oder Bug?

Über Tipps bin ich sehr dankbar!

Viele Grüße

Olaf

[kglad]

in the future, to find the best place to post your message, use the list here, https://community.adobe.com/

p.s. i don't think the adobe website, and forums in particular, are easy to navigate, so don't spend a lot of time searching that forum list. do your best and we'll move the post (like this one has already been moved) if it helps you get responses.

<"moved from cc desktop">

[reproo2773183]

Hi Olaf,

You are not doing antything wrong.

Lightroom's Panorama and HDR Merges to DNG have always been lossy compressed.

I think the report bit that said type "Digital Negative/Lossless" was the "bug".

You should expect the significantly reduced file size because JPEG XL is a lot more efficient than JPEG.

You should NOT expect significantly reduced resolution.

Maybe check if the Merge is using the less sharp of the originals?

[Olaf314551382lie]

Hi reproo2773183,

Thank you so much for your comment! You are right!

I just tried HDR merging 3 Nikon RAW files (47 MB, 50 MB, 53 MB) using my old computer (LrC Version 12.5 + Camera Raw-Version: 15.5) and got an HDR DNG with a size of 151 MB.

With my new PC (LrC Version 13.0.1 und Camera Raw 16.0) I merged the exact identical NEFs, resulting in an HDR DNG size of just 28 MB.

When comparing both HDRs side by side in 100 % view (or even enlarged to 200 % and virtually exposing + 2 f-stops to better be able to assess the dark parts of the image) - I couldn't identify visible differences, despite the file size reduction by approx. a factor of 5. How is this possible? New/better algorithm?

I guess I was confused by the terminology „Digitales Negativ/Verlustreich komprimiert“, corresponding to the smaller size and „Digitales Negativ/Verlustfrei“ for the original one.

Thanks again for your help!

Best regards,

Olaf

[Ross2511000501vd]

Hello all, I wondered if you can help me.

When taking bracketed shots, I have been merging them in Lightroom as an HDR merge. To give you an examples my RAW files are each 85MB in size. I am generally merging 5 shots. Once it has created the HDR merge, which provides a DNG file, the size is reduced to 14MB for the stacked file. Is this correct or is there something I am missing? I believed that the idea with stacking or bracketing was to retain more data from each shot. Am I wrong in thinking that the size of the output DNG file should be as large as all RAW files put together? Please do let me know any thoughts or if there is something I am missing or have done incorrectly. I have attached a sample photo showing the smaller merged file and the original RAW file.
Many thanks

Ross