HDR - Lightroom JPG+gain map support, AVIF updates in Apple Sonoma/iOS 18

[umlautnord]

I love editing in HDR in Lightroom. I've done a bunch of experimentation with improved HDR image format support in MacOS Sonoma and iOS/iPadOS 18. I thought I'd share what I've found, as there are some solid improvements! It's definitely going to increase my use of HDR in Lightroom after the limitations of Sonoma/iOS 17.

Obviously, this isn't official documentation, but I hope my experience is helpful. Overall, I tend to do any significant editing in Lightroom and then move images back into Apple Photos for "complete" library storage. I've been exporting HDR AVIF out of Lightroom until now. Looks great on my iPhone, but Apple software is pretty tetchy about sharing it. And, does a miserable job displaying it on non-XDR displays.

I'm using a MBP 13" M1 (display is capable of 1 stop of HDR), Sequoia 15.0; an iPhone 12 w/XDR display (capable of 3 stops), iOS 18.0; and some on an iPad Pro 11" 2nd Gen (1 stop), iPadOS 18.0. Those with MBPs or the iPad Pros with XDR screens are likely seeing different behavior on MacOS and iPadOS.

The great: JPG + gain map

Google/Adobe's implementation of JPG + gain map seems to be supported in Apple Photos on XDR displays! This is huge in terms of cross-platform compatibility, as JPG+gain has had major support elsewhere, but Apple has only used their own standard. Now, we've got an HDR format coming out of Lightroom that will display as HDR in Apple Photos and is broadly portable/shareable.

Unfortunately, Photos seems to be the only (Apple) software to display a JPG w/gain map in HDR on iOS. Mail and Files both show the SDR fallback. That's particularly weird to me given that AVIFs will display in HDR there. They did so even in iOS 17. I do need to do more testing with Messages/iMessage. Safari also sticks with the SDR fallback in iOS 18, so far.

Apple's implementation is also nice in that sharing tools don't seem to strip the gain map from the JPG easily. I mention this specifically because you have had to be really careful when sharing an HDR AVIF. Apple likes/liked to mess with the file or format. Here, most of my attempts to export/share a JPG+gain map image retain the gain map—even if you're sharing from a device or software that can't display it.

On MacOS, Apple software still only displays the SDR fallback in all cases. Chrome does display JPG+gain in HDR on MacOS, as it has done with AVIFs.

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HDR AVIFs: The Good

The AVIF situation is getting... better? As I noted before, Apple would display an HDR AVIF properly on iOS Photos, Mail, Messages (I think), and Files, on an iPhone XDR display. However, the same AVIF could look horrible in Apple software on non-XDR displays like my MBP and iPad Pro. Blown out, weird colors, etc.

With iPadOS 18/Sequoia, I see notably better SDR mapping/rendering of HDR AVIFs in Apple software on those non-XDR displays. Sequoia tone maps them down to a decent SDR rendering if you open them in Preview, Finder, and even Safari. Same in iPadOS, including iPadOS Photos.

HDR AVIFs: The Bad? MacOS Photos

The exception re HDR AVIFs is Photos on MacOS, which has always kind of been a pain point for me. Two key notes:

- Improved HDR AVIF tone mapping in MacOS does not extend into MacOS Photos. It still displays the same blown out rendering of an HDR AVIF that you'd see across the system previously in Sonoma.

- An unfixed holdover from Sonoma regards importing HDR AVIFs into the Apple Photos iCloud ecosystem. I continue to have issues with HDR AVIFs if imported into Apple Photos on MacOS. It'll stay an AVIF, but there will be color issues, banding, etc when it syncs through iCloud and is viewed on an XDR screen. I find that an HDR AVIF needs to go into iCloud from Photos on iOS. That means Airdropping to an iPhone from LrC/LrD exports on MacOS, or just saving directly out of Lightroom Mobile. I don't have an answer to why MacOS Photos does this, but I've tested it extensively. 

(It seems that JPG+gain map files can be directly imported into MacOS Photos without the iOS workaround.)

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So! I hope that's helpful. Tagging @gregbenz - in case you're interested/this is useful—I'm sure you're doing plenty of your own testing, too. Many thanks for the resources you've got already (https://gregbenzphotography.com/hdr/ is a must read for those not familiar).

I'm really hoping to see Safari support HDR JPG+gain map and/or HDR AVIF soon, particularly because all browsers have to use its rendering engine on iOS—home to the vast majority of Apple XDR screens. And, hopefully future iOS 18 upgrades will get us wider JPG+gain map display support across Apple software there.

Would love to hear if people are seeing similar things, other behavior, have other tips, etc. 

[gregbenz]

Have you logged issues where images did not properly display in Apple Feedback Assistant? I'd recommend sending examples. It has been my experience that support can be mixed based on little details (for example, sRGB tends to show poor color while P3 is more likely to work).

Glad you're finding those resources helpful!

[umlautnord]

I haven't—that's a good idea. I'll try to do that as I run across some!

And yeah, I figured out pretty quickly sRGB was a no-go. I think at one point having Camera Raw metadata embedded might have made a difference with an AVIF, but I couldn't replicate it? Anyway, will do on logging stuff. Thanks again!

[gregbenz]

I have not seen any issues related to ACR metadata. Color space has been a
consistent watchout, and of course the specifics of which gain map encoding
create risks (I'll be very happy to see the ISO standard finalized).

[umlautnord]

Cool, good to know that I shouldn't watch out for that. Must have been another issue and I wasn't tracking individual variables closely enough. Definitely agreed on finalized standards. Thanks Greg!

[Monstieur]

Reposting this from another thread for visibility.

AirDrop to iOS no longer works with AVIF gain maps. When you first AirDrop the files, iOS 18.2 Photos displays the gain maps after a delay of about two seconds. Previously, the gain maps were displayed instantly. Then, after the files are uploaded to iCloud, the gain maps stop working completely as if you had imported the files on macOS. Once in a while, some photos might display the gain map after about ten seconds, but they usually never do.

There is a workaround where if you edit a photo on either iOS or macOS Photos using the magic wand or by making a trivial change, the gain map starts working instantly. On some photos, if you revert the edit, the gain map continues working, but on most photos you must keep a trivial edit for the gain map to work.

My previously imported photos using iOS 17 and Lightroom Classic 13 still have working gain maps that display instantly. I'm not sure if the issue is with Lightroom Classic 14 or iOS 18.

[Monstieur]

It turns out my old photos are AVIF native HDR without a gain map, which is why they work correctly. This is still the case today. AVIF native HDR works fine but AVIF gain maps don't. Only JPEG gain maps are reliable.

[gregbenz]

JPG with a gain map is ideal for sharing. It looks great on both SDR and HDR systems when properly encoded.

HDR AVIF (ie no gain map) works great on an HDR system with full headroom, but will often look terrible on displays which are SDR only or have limited headroom. It is safe for personal use, and offers significantly smaller files (especially comparing JPG with a gain map to AVIF with no gain map).

AVIF with a gain map has almost no support (just Adobe software and browsers with the dev flag). It will be a great choice in ~12 months. But the main reason to use now is probably just to identify any bugs or quality issues to ensure they are resolved as we wait for more broad support.

When you refer to a rendering delay, I am unclear if you mean a quality issue or just the normal ramping to full HDR support that Apple software does. It is probably the latter. If you are switching between SDR and HDR content, there is often a lag. But you generally won't see it if switching through several HDR photos. It would be ideal if there was no ramp (in my opinion), but it is the current behavior and may affect any HDR content (ie not a "bug" in the sense of how a specific image is handled, just the standard behavior of the operating system).

[Monstieur]

The rendering delay for AVIF gain maps in macOS / iOS is not the usual ramp up to maximum brightness. It first displays the SDR base image for several seconds, then abruptly switches to HDR when it loads the gain map. If you make a trivial edit to the photo in the Photos app, the gain map then loads instantly when opening the image in future. Sometimes if you revert the edit, the gain map will remain fixed and load instantly, but usually it goes back to the rendering delay unless you keep the edit.

[Monstieur]

My AVIF files are full resolution 60 megapixel photos, so that could be exasperbating any issues.

[gregbenz]

That is very possibly a key factor. The actual pixel dimensions could run into some limitations. And the computation is significant. Your edit likely renders a new format (or perhaps a cache file) which then avoid the delay.

Any reason you would share a finished image (gain maps are not suitable for further editing) at a resolution vastly exceeding 8k resolution? I'd stick with a monitor native resolution, 4k, or if really important consider 8k. But even 8k is only about 33MP.

[Monstieur]

I don't share any images outside of my shared iCloud Photo Library. I want these images at native camera resolution so I can zoom into people's faces or see fine detail in places from my travel. I keep all my RAW files so when there is a better image format I can re-export everything.

[gregbenz]

feel free to post an image for review along with a specific workflow that replicates that experience.

[gregbenz]

HDR AVIF (without a gain map) is probably best for that (since you are not sharing).

You won't benefit from the gain map most of the time since you expect to have great HDR support (though it woudl apply if you set brightness high or are in bright ambient light). A simple AVIF is smaller and it sounds like probably more performant at than a gain map such a high resolution.

[BroStack]

Hey,

just found your post. I have tried exporting AVIF, AVIF with maximum compatibility, JPEG XL, JPEG with Gain maps and none of these seem to sync via iTunes (I have a windows machine). I have an iPhone 13 Pro, but Apple states that any iPhone from 12 upwards supports HDR images. Only JPEGs with gain maps show up, but without HDR. 

On the contrary files exported from Lightroom on my iPhone have proper HDR compatibilty and shine as intended. Have you tried iTunes sync or have native iCloud sync?

[Monstieur]

If AVIF native HDR (maximize compatibility disabled) isn't working, then the files are being transcoded during transfer. If you do not have macOS, you have to use cloud storage to transfer the files to iOS. Then use the Files app to import them to the Photos app in small batches. If you try to import too many at once it, all the photos won't import. You'll know the import completed successfully when all the files get deselected automatically. If all the files do not get deselected, then some where not imported. Alternatively, use AirDrop from the Files app to send all the files directly to the Photos app on another iOS device. This reliably imports all the files at once.