P: replace jpeg export code with jpegli for increased compression efficiency

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LR’s implementation of the JPEG XL Export format (suggested as an alternative to “jpegli”) is not ready for prime time, with two significant bugs that have gone unfixed by Adobe since Export started supporting it 2.5 years ago in LR 13.0.

- It generates visually noticeable color artifacts with the color spaces Prophoto and Adobe RGB.  Adobe developers declared this a limitation of the JPEG XL standard, which is a silly claim, since neither the JPEG XL reference utilities nor Photoshop generate those artifacts.

- It generates JPEG XL files that are several times larger than they should be:

Given these bugs have been outstanding for so long, it’s clear Adobe hasn’t prioritized support for the format, and it’s not ready for professional use.

Note that the DNG format uses the JPEG XL compression algorithm, but these issues do not occur with DNG’s created by LR or Camera Raw.

Adobe may not want to rely on an open source library that is out of their control, with all the technical and legal complications that can bring.

Ian Lyons and Val737, I think there is a severe misunderstanding here. The thread opener has been asking for jpegli, which is entirely different from JPEG XL. They are not the same. JPEG XL is a separated format from the old *.jpg format, with modern technicalities but has the same compatibility issues as those came before it like JPEG 2000 or JPEG XR. Meanwhile, jpegli is a modern encoding library for the *.jpg format itself, with enhanced computing techniques to make the encoding process much more efficient but still maintains perfect backwards compatibility (with the right settings, of course). 

JPEG XL is the one that requires significant processing power, while jpegli is largely the same as old *.jpg format in encoding speed (actually most of time jpegli is faster, but in daily workflows it should not be noticeable since old *.jpg is already fast enough in the current era of multi-core CPUs). Val737, please remember this fact as it is the correct one, unlike yours.

Files encoded using jpegli will have much better quality at the same size, or about the same quality but with much smaller file size, compared to old *.jpg. And on top of that, I must repeat again, those files will not have any compatibility issues. Every software that can read old *.jpg will also read new jpegli-encoded files easily and reproduce the same image, same colors, no problem. The only thing that can mess up compatibility is the “XYB colorspace” option, stay away from that and there will be no worries at all. Simple.

For decades, old *.jpg was already good enough for the vast majority of people. Now, with jpegli as a huge improvement of that same old format, it should be the default save/export choice. Everyone will benefit from it. No need to change the UI, just replace the processing pipeline underneath and omit the “XYB colorspace” option (or just tuck it somewhere else as an ‘advanced option’ separately). Should be a no-brainer at this point.

Did you know that jpegli files are decoded almost twice as slowly as regular jpegs?

I would prefer to have a choice between the regular jpeg format and jpegli.

JPEG XL is a new format, whereas JPEGLI use some of the improved algorithms from JPEG XL but it produce 100% standard compliant jpeg files. It would be a win-win situation to use this new jpeg encoder for standard jpeg files.

Both LrC and Camera Raw can export images in JPEG XL. Have you tried it?