Not able to see improvement with HDR compatibility between Lightroom and Apple Photos

Report · Oct 14, 2024

In a recent blog post about the newest updates to Lightroom, we can read:

>Embedded ISO HDR Gain Map support on export also means you no longer have to create two separate files for SDR and HDR. The HDR Gain Map will enable showing either the SDR or HDR rendition of your photo automatically based on display capabilities, ensuring a consistent viewing experience across devices. HDR Gain Maps are now supported in many apps such as Apple Photos, Google Chrome, and Instagram.

I quickly updated the Lightroom desktop to v. 8.0 to check it. I took one of the files I developed with the HDR effect and exported it to JPEG plus JPEGXL and AVIF with "HDR output" selected.

I don't see any difference. As in previous versions of Lightroom, AVIF and JPEGXL are HDR 10-bit images with no gain map. They look great* in Apple Photos on HDR displays but terrible otherwise. The JPG file does contain a gain map, but that happened after exporting from the previous version of Lightroom as well. Likewise, it is still not compatible with Apple Photos, despite what the blog post said: there, it always displays only an SDR base image.

In other words, I struggle to understand what the "update" is about. Lightroom seems to behave exactly the same as before, I don't see any substantial changes in the exporting interface of HDR images, and images themselves seem to be equally (in)compatible with other software as before.

*Usually, sometimes there are artefacts after syncing through iCloud visible on other devices, but I suppose that is a bug in Apple's software.

Report · Oct 15, 2024

I'm not entirely convinced, based on file size alone (comparing to Lightroom Classic exports using "maximize compatibility," which ensures a gain map is included), that Lightroom Desktop 8.0 is actually spitting out SDR + gain map images. That's what an ("HDR" JPG does).

If the default display of the image is HDR, or if it is HDR-only, it's going to look wonky in various situations depending on how it's tone mapped. Apple has gotten a lot better at tone mapping HDR-only images, so they don't look awful, but it isn't actually the "SDR version" if a gain map isn't being processed somehow.

It's possible that the standard uses HDR as a base minus gain map, but I'm unclear on that (again based on what Classic is doing), too. And again, file size makes me think there isn't a gain map included on what's coming out of Desktop 8.0.

I may be wrong, but, I think there may be a little dust settling to happen here!

(Btw, I also have the Apple iCloud artifact issues with AVIFs/JXLs... my tip is to airdrop to an iPhone once you export out of Desktop. Don't import them on MacOS Photos.)

Report · Oct 15, 2024

Hi, thanks for the comments. To be clear, I used Adobe's own "Gain map demo app," which they released as a demo tool a year or two ago. When you open any HDR file in it, it will actually tell you if it contains a gain map or is just a single HDR image. I don't really use Classic, but Lightroom was adding a gain map automatically in JPEG exports if one first edits RAW in HDR. It was already working like that in the previous version.

This is why I'm confused about what changed and how this "improves" compatibility with Photos. Photos (on all platforms) still seem incapable of reading Lightroom-derived JPEGs with gain map correctly: will always show just SDR base in such files. As for AVIF and JPEGXLs, if one exports HDR-edited raw and selects "HDR output" during exports into that format, it just creates higher bit depth HDR files without a gain map. Those still look bad in macOS Photos because, for some reason, global tone mapper in Photos is not working correctly (other apps, like Preview or QuickLook, seem to render them ok).

Anyway, there are no gain maps in AVIF or JPEG XL; gain maps in JPEGs were there already, and if those are some "new" and "ISO HDR", at least with Photos, they (don't) work the same as previously.

Report · Oct 15, 2024

Are you importing the JPG+gain map into Photos on MacOS? I have seen that it will strip the gain map no matter what. I always have to Airdrop it to my iPhone, where it's imported into Photos. Then, the gain map works in Photos on an iPhone, and renders base SDR on a standard Mac screen. That's the expected behavior; this is with the latest iOS. I do the same with pure HDR AVIFs to avoid artifacts. I don't understand why MacOS Photos is so grumpy about HDR, but, it's my workaround.

Yes—I agree that currently, I do not see Lightroom Desktop outputting anything other than the HDR-only files as it has before. No gain maps. I think this is a bug/issue/something. This is not the behavior that should be happening as described in the update notes. I haven't tested the iOS exports extensively to be totally sure what they're doing at this point, but the one test I did of an AVIF also seemed to be pure HDR. Which would also be a bug/issue.

I will say that I'm not sure the Gain Map Demo App is fully up to handling the latest standards even if the files are totally correct; it hasn't been updated since February. Seemingly unlike Desktop, Lightroom Classic is able to spit out SDR AVIFs with a gain map (which I can verify in Photos, using the same Airdrop method to avoid the gain map getting stripped). However, the demo app just says it's an SDR image without a gain map, which is incorrect.

I suspect that we'll need to wait for a bug fix for Desktop (and maybe iOS). Usual disclaimer that I'm not an authority on this, but, this is all to the best of my understanding 🙂

Report · Oct 15, 2024

It works! The AVIF file with gain maps from LrC airdropped to the iPhone syncs correctly and is even displayed correctly on the SDR and HDR screens in the Desktop app. Thank you; this was making me mad!

EDIT: I was wrong, they still work incorrectly after sync, even if I airdrop them to iPhone. The only difference is that the files withe the new maps seem to display after syncing SDR version, so its not immediately obvious something is wrong.

Report · Oct 16, 2024

Not entirely sure what you mean—where is it displaying the proper SDR rendition, and where is it displaying in HDR? And what are the specific devices you're using?