Support for ISO Gain Map HDR images

[Martin Stolle]

Hi,

Adobe recently introduced pervasive support for Gain Maps when exporting HDR photos. ("maximize compatibility" in Lightroom Classic export, default in Lightroom CC).  This seems to create an SDR image + extra information (gain map) to generate an HDR image.  When processing such an image in PT Gui, only the SDR information is processed and the gainmap seems to be lost => the result is an HDR image with only SDR brightness.

I tried with both 12.7 and 13 beta 8 .

(For comparison, without "maximize compatibility" (the previous default/only option), I am able to round trip HDR images through PT Gui 12.7 no problem (using 32 bit TIFs with Rec 2020 profile).  Unfortunately, Lightroom CC doesn't allow for this any more and plugins in Classic cannot turn off "maximize compatibility")

Thanks,

  Martin

[PTGui Support]

Hi Martin,

I will add this to the wish list.

However, I quickly tried but couldn't find the option in Lightroom.
Merge to HDR gives me a DNG image which is a non tonemapped HDR image.
Where can I find it?

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[mar...@stolle.name]

PTGui Support schrieb am Montag, 21. Oktober 2024 um 09:03:04 UTC+2:

Hi Martin,

I will add this to the wish list.

However, I quickly tried but couldn't find the option in Lightroom.
Merge to HDR gives me a DNG image which is a non tonemapped HDR image.
Where can I find it?

"Merge HDR" is not necessary.  Take any photo in Lightroom and enable HDR processing (even sRGB JPEGs have some HDR headroom, but RAWs from an SLR presumably work best): 

 

Then when exporting, the export dialog has different options:

I hope this helps?

Martin

[PTGui Support]

Couldn't you just as well underexpose 1 or 2 EV when developing your raw
file and save as 16 bit tiff?

Also any headroom they claim to extract from jpegs would be artificial,
I guess by applying a curve.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 21-10-2024 23:34, mar...@stolle.name wrote:
>
>
> PTGui Support schrieb am Montag, 21. Oktober 2024 um 09:03:04 UTC+2:
>
> Hi Martin,
>
> I will add this to the wish list.
>
> However, I quickly tried but couldn't find the option in Lightroom.
> Merge to HDR gives me a DNG image which is a non tonemapped HDR image.
> Where can I find it?
>
>
> "Merge HDR" is not necessary.  Take any photo in Lightroom and enable
> HDR processing (even sRGB JPEGs have some HDR headroom, but RAWs from an
> SLR presumably work best):

> Screenshot 2024-10-21 232609.png
>
>
> Then when exporting, the export dialog has different options:
>

> Screenshot 2024-10-21 232920.png
>
> I hope this helps?
>
> Martin
>
>
>
> Kind regards,
>
> Joost Nieuwenhuijse

> www.ptgui.com <http://www.ptgui.com>

> groups.google.com/d/ <https://groups.google.com/d/>
> > msgid/ptgui/CAEkOg2V3m3bDskxR5bL8wcm3%3DJ57Me4-
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> utm_medium=email&utm_source=footer <http://40mail.gmail.com?
> utm_medium=email&utm_source=footer>>.

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[Martin Stolle]

Am Di., 22. Okt. 2024 um 10:02 Uhr schrieb 'PTGui Support' via PTGui Support <pt...@googlegroups.com>:

Couldn't you just as well underexpose 1 or 2 EV when developing your raw
file and save as 16 bit tiff?

I haven't tried with a 16 bit tiff, but I suspect that the result would be the same.  Also, needing to develop panormas differently (and then undoing it after re-importing the stitched panorama) seems a bit clumsy.

 

Also any headroom they claim to extract from jpegs would be artificial,
I guess by applying a curve.

Yeah, I haven't really used that - it was just an off-hand comment on ways to obtain an HDR image to reproduce the feature request (bug?). (Note that there are both proprietary and (recently) standardized ways to store additional information in JPEGs to be able to reconstruct an HDR image with real headroom from it, but that shouldn't be directly relevant to this bug, as the export from Lightroom isolates that output from the input.)

You are probably familiar with Greg Benz's description of true HDR images, but if not, it's worth a read: https://gregbenzphotography.com/hdr/

 

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[PTGui Support]

On 22-10-2024 11:53, Martin Stolle wrote:
> Am Di., 22. Okt. 2024 um 10:02 Uhr schrieb 'PTGui Support' via PTGui

> Support <pt...@googlegroups.com <mailto:pt...@googlegroups.com>>:

>
> Couldn't you just as well underexpose 1 or 2 EV when developing your
> raw
> file and save as 16 bit tiff?
>
>
> I haven't tried with a 16 bit tiff, but I suspect that the result would
> be the same.  Also, needing to develop panormas differently (and then
> undoing it after re-importing the stitched panorama) seems a bit clumsy.

IMO the clumsyness is on Adobe; they could have offered a simple
non-clipped linear floating point TIFF or EXR output.

> You are probably familiar with Greg Benz's description of true HDR
> images, but if not, it's worth a read: https://gregbenzphotography.com/

> hdr/ <https://gregbenzphotography.com/hdr/>

Yes I think this the actual use case for Gain Maps: as a final image
which can be displayed both on SDR and HDR displays. If you just need
the HDR image for post processing, there are (or there should be) more
straightforward options.

But I'm just ranting now. I've added this to the wish list.

Joost

[Martin Stolle]

Am Di., 22. Okt. 2024 um 12:31 Uhr schrieb 'PTGui Support' via PTGui Support <pt...@googlegroups.com>:

On 22-10-2024 11:53, Martin Stolle wrote:
> Am Di., 22. Okt. 2024 um 10:02 Uhr schrieb 'PTGui Support' via PTGui
> Support <pt...@googlegroups.com <mailto:pt...@googlegroups.com>>:
>
>     Couldn't you just as well underexpose 1 or 2 EV when developing your
>     raw
>     file and save as 16 bit tiff?
>
>
> I haven't tried with a 16 bit tiff, but I suspect that the result would
> be the same.  Also, needing to develop panormas differently (and then
> undoing it after re-importing the stitched panorama) seems a bit clumsy.

IMO the clumsyness is on Adobe; they could have offered a simple
non-clipped linear floating point TIFF or EXR output.

Just to be clear - that's what Adobe *used* to do and still *can do*. However, they have added the "maximize compatibility" option which seems to do SDR + gain map and made it the new default (a choice one could argue over, but not an insurmountable problem by itself). The real problem is that there is no documented way for *plugins* to perform an export that does *not* have the new option turned on.

 

> You are probably familiar with Greg Benz's description of true HDR
> images, but if not, it's worth a read: https://gregbenzphotography.com/
> hdr/ <https://gregbenzphotography.com/hdr/>

Yes I think this the actual use case for Gain Maps: as a final image
which can be displayed both on SDR and HDR displays. If you just need
the HDR image for post processing, there are (or there should be) more
straightforward options.

But I'm just ranting now. I've added this to the wish list.

Thanks!

 

Martin