DNG 1.7 (Camera RAW 16) / JPEG XL / lossy support

[golemus]

Dunno how many have noticed but DNG format has had a major change since version 1.7 (or was it already 1.6) with inclusion of JPEG XL compression. It makes RAW files much smaller.

e.g. some old CR2 and RW2 files space consumption reduce up to 70%. Of course it is lossy so some information will be lost but it is good for pics that are not very important and you still want to keep option open for RAW noise removal and levels adjustment.

XNView MP does not support it. Actually XNView MP barely supports any DNG lossy compressions even from older versions and DNG has lot of bugs (sometimes colors render differently than other times).

I did tests with Adobe DNG converter and there seems to be couple of different parameters that affect how well XNView (and other programs) can handle it:

- lossy vs. lossless RAW compression. Lossy in general seems to cause issues. Anyway with JPEG XL space savings starts to be so large that IMO it is worth of implementing.

- presence of preview image. If XNView settings there is "Camera Raw: Embedded, half RAW, full RAW". Sometimes (although rarely) you get files where quality of preview is bad and you would want to look at RAW image without modifying the setting. Is there some keyboard shortcut that would open the RAW file instead of the preview file?

- presence of "Embed Fast Load Data". This setting is supposed to make RAW processing faster but as side effect I noticed with some programs (Faststone) problems of rendering RAW correctly).


- a bit of side question is there some difference between Camera RAW 16 and DNG 1.7.1 or does it just mean that Camera RAW 16 = "DNG 1.7.1 without demosaicing and uncompressed data" ?

[golemus]

I am thinking of converting all of my RAW files now even that they will not open and I am curious which settings I should use for XNView MP to be able to open it when there is (hopefully) support. e.g. should Embed Fast Load Data be enabled..

[xhiko_canhoto]

I'm kind of in the same boat, thinking of converting thousands of low priority images into lossy DNG, but the only viewer that works reliably with them is FastRawViewer, and i really prefer xnview, especially because i'd like to see all my images in a single place, and i have lots of JPGs, HEIFs etc.

[xnview]

could you send us sample file?

[golemus]

could you send us sample file?

I can send a bit later but I am sure it will be easy for you to do them your self also like this:

1. install adobe DNG converter (free tool from Adobe)
2. take any RAW file (Canon CR2, Panasonic RW2, etc...)
3. choose target file format as "Camera RAW 16 and later" or Custom and from there DNG 1.7 or 1.7.1
4. check that "Use lossy compression" checkmark is enabled

It will produce DNG file which is much smaller than original. 10MB CR2 makes maybe 2-4MB DNG?, file size varies a little bit depending on which size JPEG Preview is chosen (although I think/suspect that with DNG 1.7.x or later even the preview might? be compressed as JPEG XL. RAW data is definitely JPEG XL algorithm compressed as that is kind of the thing of DNG 1.7.x.

If you don't choose "use lossy compression" it might make a file where RAW compression is compatible, don't remember exactly.

But I live under the impression that Adobe DNG converter is same tool/component that majority of DNG files are produced with so it is any way good to test with that tool. In addition of course modern cameras or at least android cameras can produce DNG. BUT good detail to know is that at least Samsung Galaxy produced DNG files do not seem to have embedded preview at all.

[xhiko_canhoto]

here is a sample for a lossy dng that xnview will not display: https://1drv.ms/i/s!AmoiUQKSR_x9keIfJ4SGOagPGdQFSg