Do the HDR exports contain gain maps?

[sylwesterg95401861]

Hi,

I have a question regarding HDR editing and export in the newest update to Lightroom.

I've been testing it since yesterday, and in general, it works great—as long as I'm working on HDR displays and also viewing the exported files on an HDR display (e.g., on an iPhone or the internal HDR display on my MacBook). However, I've noticed that exported AVIF or JPG XL files are heavily clipped when displayed on a non-HDR display, such as the Apple Studio display.

This behavior is different compared to HDR pictures created by the iPhone camera. Those show extended highlights when displayed on an HDR display but also exhibit nice tone mapping when displayed on a non-HDR display.

I even tested it with Lightroom: I imported an HDR HEIF made on an iPhone into Lightroom, and Lightroom displayed it nicely in HDR during editing. I then exported it back to Apple Photos as an HDR AVIF. On the iPhone and MacBook HDR displays, the original and exported files looked essentially the same. However, when I moved the Photos window to the Studio display, the original iPhone picture still looked nice and tone-mapped, while the AVIF was heavily clipped.

Now, after watching this video, https://youtu.be/HBVBLV9KZNI?si=5l3ozsiM16Xq5cAV  I understand that Apple and Adobe are working together to introduce a gain map-based HDR standard for still images. As I understand it, gain maps are precisely what allow for controlled compatibility and tone mapping of a single image so that it looks great on both HDR and SDR displays.

My question is: Are the HDR files currently exported from Lightroom lacking gain maps, which is why they are not compatible with SDR displays? Or is it that Apple Photos software doesn't yet fully support AVIF HDR files with gain maps, but the images are, in principle, future-proof and already have gain maps encoded? Could we expect that, with the right software, they would look more like the "SDR preview" in Lightroom, available in HDR editing mode?

[JohanElzenga]

AFAIK, you can select to add a gaim map if you export an HDR image as JPEG. The support for gain maps is very limited at present however. Google Chrome apparently supports them, but I think that's about it. And yes, if the software supports them, then your image will look like the 'SDR preview' when viewed on an SDR display.

[sylwesterg95401861]

Ok, I checked JPG with "HDR output" and in conditions described by me above it is not clipping, but it is also not HDR, at least when displayed in Apple Photos and judged by eye. So it seems to me that current state of support is still generally half-there and there is no way to create image that would look good on HDR and SDR displays. 

[JohanElzenga]

I think my initial remark was not entirely correct. The way I understand it is as follows. By itself, JPEG does not support HDR. If you export as JPEG with HDR enabled, then the SDR Preview will be exported as the base JPEG image. That means no clipping, but also no HDR. What the gain map does is add the HDR information, so an app that does support gain maps can show the image in HDR.

[swrobel]

How can I export a JPG with "HDR output." I see an option for AVIF exports, but not for JPG:

[Rikk Flohr: Photography]

You don't 'set' anything. If your image had HDR components and you export it as JPG, the Gain Map is included as needed. There isn't an HDR setting such as for an AVIF or a JXL. 

[Rikk Flohr: Photography · Accepted solution]

JPG Files can contain a Gain Map if they have HDR Information.  AVIF and JXL do not yet contain Gain Maps

[alanr72382327]

If AVIF and JXL don't support gain maps yet, does that mean the SDR settings have no effect? I've been trying to switch to HDR, but there are still too many surfaces where HDR isn't supported and the current outputs with no gain maps get completely blown out so they're practically unviewable.

[Rikk Flohr: Photography]

"If AVIF and JXL don't support gain maps yet, does that mean the SDR settings have no effect?"
With regard to Exported files, that is correct. 

[sylwesterg95401861]

Hi Rikk,

I understand that it might be to early to say/reveal, but should we expect some changes on how HDR is handled in coming months? My understanding based on videos from newest WWDC is that Apple want to push for standardization of "Adaptive HDR" in jpg and heif formats. What's more they explicitly stated that they understand by that both BW low res gain maps in their original implementation as well as full res color (I understand that how hdr jpgs exported from Lightroom works). Can we (ever) expect support for HDR HEIFs export from Lightroom? 

[Enlightened_view15C3]

You can also test for gain maps with Adobe's demo tool, which I show towards the end of my video on gain maps: https://gregbenzphotography.com/hdr-images/jpg-hdr-gain-maps-in-adobe-camera-raw/

[sylwesterg95401861]

Yep, I checked it.  I hope there will be support for gain maps in AVIF/HEIF in both Lightroom and Apple photos, otherwise as it stand now exporting HDR pics create a lot of strange display issues in grid view in Apple Photos, and is not really working on non-HDR displays (and I have a few: iPad, MacBook Air, Studio Display etc). It is really frustrtating since it sseem all parties agreed on standards and yet not implemented those (yet?).

[Enlightened_view15C3]

FYI on a related feature request I've submitted on custom gain maps to allow greater artist control to improve quality: 

https://community.adobe.com/t5/photoshop-ecosystem-ideas/allow-full-user-control-of-the-sdr-renditio...