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sylwesterg95401861
sylwesterg95401861
Known Participant
October 10, 2023
Answered

Do the HDR exports contain gain maps?

  • October 10, 2023
  • 3 replies
  • 5819 views

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?

    This topic has been closed for replies.
    Correct answer Rikk Flohr_Photography

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

    3 replies

    G
    gregbenz
    Inspiring
    November 2, 2023

    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
      sylwesterg95401861Author
      Known Participant
      November 3, 2023

      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?).

      G
      gregbenz
      Inspiring
      November 3, 2023

      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-rendition-in-an-hdr-gain-map-export/idi-p/14205440

        Rikk Flohr_Photography
        Community Manager
        Rikk Flohr_PhotographyCommunity ManagerCorrect answer
        Community Manager
        October 10, 2023

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

        Rikk Flohr: Adobe Photography Org
          X
          xu_ivan0929
          Participant
          October 15, 2024

          Hi~ for export AVIF/JXL with HDR gain maps, October release notes for lightroom said that now gain map is supported in export HDR photos, is that means we can export AVIF/JXL with gain maps? or still there are other limitations.

          sylwesterg95401861
          sylwesterg95401861Author
          Known Participant
          October 15, 2024

          That is supported now too, when you enabled both HDR output and "maximize compatibility" (the latter is assumed if not shown as an option, such as when exporting HDR content as a JPG - since the base image would not support HDR without a gain map).


          Does this work only in Lightroom Classic? I don't see such an option in Lightroom (Desktop).

          JohanElzenga
          Community Expert
          JohanElzengaCommunity Expert
          Community Expert
          October 10, 2023

          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.

           

          -- Johan W. Elzenga
          sylwesterg95401861
          sylwesterg95401861Author
          Known Participant
          October 10, 2023

          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
          Community Expert
          JohanElzengaCommunity Expert
          Community Expert
          October 10, 2023

          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.

           

          -- Johan W. Elzenga
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