DNG bracket merge lacks quality of the source images

[Greg Benz]

I'm looking to do a merge of multiple exposures (brackets) with multiple camera angles (pano). My goal is to output a high-quality DNG which I can then process in Lightroom (using the "HDR" mode to support HDR display). 

To keep things simple, I'm just testing the brackets for now. 

My approach:

1. Open 5 source images (DNG files from a DJI drone)
2. I select the images in "source images" tab, right-click and choose "link selected images".
3. In the "create panorama tab", I set HDR file format to DNG and have the output checked only for "HDR panorama".

The output is a valid DNG, however the quality is reduced compared to the source images. The color profile option in Lightroom only shows "color" as an option, whereas the source images are supported with "Adobe Landscape" and other similar options (this is also true if I use LR's "merge to HDR" to create a single DNG from my 5 original DNG captures. 

Additionally, the color is very different. My source has yellow sunset clouds, whereas the PTGui DNG shows a rather pink result. The output from LR is much more consistent with the original images. 

I see that the LrC output is DNG v1.7 16-bit float (with lossy JXL compression), while the PTGui output is DNG v1.6 32-bit float (no compression or preview). I'm not sure if this is relevant, but it jumps out as a clear difference in the encoding.

Is there a way to merge to DNG with the same preservation of color and profile options that I see from LR's merge?

Thank you,

Greg

[PTGui Support]

Hi Greg,

I have your files, I will investigate.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 1/2/26 00:33, Greg Benz wrote:
> I'm looking to do a merge of multiple exposures (brackets) with multiple
> camera angles (pano). My goal is to output a high-quality DNG which I
> can then process in Lightroom (using the "HDR" mode to support HDR
> display).
> To keep things simple, I'm just testing the brackets for now.
>
> My approach:
>

> 1. Open 5 source images (DNG files from a DJI drone)
> 2. I select the images in "source images" tab, right-click and choose
> "link selected images".
> 3. In the "create panorama tab", I set HDR file format to DNG and have

> the output checked only for "HDR panorama".
>
> The output is a valid DNG, however the quality is reduced compared to
> the source images. The color profile option in Lightroom only shows
> "color" as an option, whereas the source images are supported with
> "Adobe Landscape" and other similar options (this is also true if I use
> LR's "merge to HDR" to create a single DNG from my 5 original DNG captures.
>
> Additionally, the color is very different. My source has yellow sunset
> clouds, whereas the PTGui DNG shows a rather pink result. The output
> from LR is much more consistent with the original images.
>
> I see that the LrC output is DNG v1.7 16-bit float (with lossy JXL
> compression), while the PTGui output is DNG v1.6 32-bit float (no
> compression or preview). I'm not sure if this is relevant, but it jumps
> out as a clear difference in the encoding.
>
> Is there a way to merge to DNG with the same preservation of color and
> profile options that I see from LR's merge?
>
> Thank you,
> Greg
>
>

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[Greg Benz]

Hi Joost-

Have you been able to produce a result which has quality comparable to source?

I can do that with LR merge, but with PT Gui the result is quite different. As far as I can tell, there is no option to preserve the original RAW quality.

Regards,

Greg

[PTGui Support]

Hi Greg,

I'm still investigating, will get back to you. I did see what you mean
though.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 1/13/26 16:56, Greg Benz wrote:
> Hi Joost-
>
> Have you been able to produce a result which has quality comparable to
> source?
> I can do that with LR merge, but with PT Gui the result is quite
> different. As far as I can tell, there is no option to preserve the
> original RAW quality.
>
> Regards,
> Greg
>
> On Friday, January 2, 2026 at 8:31:37 AM UTC-6 PTGui Support wrote:
>
> Hi Greg,
>
> I have your files, I will investigate.
>
> Kind regards,
>
> Joost Nieuwenhuijse

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

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[Greg Benz]

I appreciate the follow-up!

[PTGui Support]

Hi Greg,

I've investigated; I think there are 3 issues:

1- By default PTGui outputs HDR images with a brightness equivalent to
the middle bracketed image. So if you have a -2 / 0 / +2 bracket, the
HDR will look like the 0EV image in terms of brightness.

This means that some areas of the image (like the clouds in yours) will
have a brightness greater than 1.0. For true HDR formats like EXR, or
floating point tiff, this is no problem, they can store extremely bright
pixels and any decent image editor can handle that. But DNG doesn't
support this, DNG readers will clip everything above 1.0.

That is also what I see in the PTGui generated DJI_20251107182427_0502_D
Panorama_hdr.dng that you posted: much of the sky is clipped.

The solution is to reduce the brightness of the HDR output in PTGui. The
easiest way is to go the Panorama Editor, HDR Exposure and choose
'Reference: Brightest Exposure'. This outputs the DNG such that no
pixels are brighter than 1, so no clipping occurs and it looks much
better to me. This is also how lightroom generates HDR DNGs: it makes
them dark enough so that no highlights are clipped.

2- The second issues is highlight recovery: even in your darkest
exposure, parts of the clouds are clipped. You can see it by loading
just DJI_20251107182427_0505_D.dng.

When one of the color channels is clipped, we still can reconstruct the
brightness of a pixel, but the color must be guessed. Lightroom does
this better and smarter than PTGui.
I don't know if that would be a problem for this particular panorama, if
you would want to show that detail in the clouds, the panorama would be
very dark. There's room for improvement here in PTGui.

3- Indeed, ACR does not show its built in profiles for the DJI DNGs when
HDR DNG is exported from PTGui. I will also see if this can be improved.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 1/2/26 00:33, Greg Benz wrote:

> I'm looking to do a merge of multiple exposures (brackets) with multiple
> camera angles (pano). My goal is to output a high-quality DNG which I
> can then process in Lightroom (using the "HDR" mode to support HDR
> display).
> To keep things simple, I'm just testing the brackets for now.
>
> My approach:
>

> 1. Open 5 source images (DNG files from a DJI drone)
> 2. I select the images in "source images" tab, right-click and choose
> "link selected images".
> 3. In the "create panorama tab", I set HDR file format to DNG and have

> the output checked only for "HDR panorama".
>
> The output is a valid DNG, however the quality is reduced compared to
> the source images. The color profile option in Lightroom only shows
> "color" as an option, whereas the source images are supported with
> "Adobe Landscape" and other similar options (this is also true if I use
> LR's "merge to HDR" to create a single DNG from my 5 original DNG captures.
>
> Additionally, the color is very different. My source has yellow sunset
> clouds, whereas the PTGui DNG shows a rather pink result. The output
> from LR is much more consistent with the original images.
>
> I see that the LrC output is DNG v1.7 16-bit float (with lossy JXL
> compression), while the PTGui output is DNG v1.6 32-bit float (no
> compression or preview). I'm not sure if this is relevant, but it jumps
> out as a clear difference in the encoding.
>
> Is there a way to merge to DNG with the same preservation of color and
> profile options that I see from LR's merge?
>
> Thank you,
> Greg
>
>

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[Greg Benz]

Hi Joost-

Thank you so much for diving into this.

A few comments / questions:

• For #1, the DNG format output by Lightroom does not have this clipping limitation. Any reason PTGui couldn't use a similar floating point DNG encoding? It's ideal to avoid clipping in HDR, and more importantly would simplify the workflow to not need to know about clipping and manage it for each image separately in PTGui. Adobe has updated to DNG in the past couple years and this is a great option which may not have been available at the time this support was originally added in PTGui (the JXL compression can offer nice small file sizes, even when set conservative enough to be visually lossless for subsequent enlargement for print).
• For #2, I'm less concerned if the source is clipped. This would of course be ideal, but is ultimately best addressed by a proper set of exposures.
• For #3, thank you for checking into it. I believe this is the most critical. The loss of color fidelity makes the current DNG output unusable in my opinion, it's a very different result and I do not see a way to correct the color issues here.

Regards,

Greg

[PTGui Support]

Hi Greg,

On 1/16/26 20:31, Greg Benz wrote:
> * For #1, the DNG format output by Lightroom does not have this

> clipping limitation. Any reason PTGui couldn't use a similar
> floating point DNG encoding? It's ideal to avoid clipping in HDR,
> and more importantly would simplify the workflow to not need to know
> about clipping and manage it for each image separately in PTGui.
> Adobe has updated to DNG in the past couple years and this is a
> great option which may not have been available at the time this
> support was originally added in PTGui (the JXL compression can offer
> nice small file sizes, even when set conservative enough to be
> visually lossless for subsequent enlargement for print).

I'm not very familiar with Lightroom, so I may have missed something.
But when I tried generating a DNG HDR from raw source images in ACR, the
result was a DNG image dark enough such that no clipping occurs.

Regardless, I don't think it's that much of a deal: you could just
choose 'Reference: Brightest Exposure' in PTGui. You get a darker DNG,
but when post processing the DNG you can simply boost the exposure again
to the desired level. Since it's floating point, the dynamic range is
practically unlimited, you don't have to worry about posterization in
the shadows and things like that which you would have with normal images.

Joost

[Greg Benz]

That works to avoid highlight clipping, but the workflow is complicated. 

In Lightroom, you select the images and choose to merge to HDR pano. That's it. 

In PT Gui, you have to:

(1) find all the related HDR frames, shift-click to select them, then right-clink and "link selected images". For a typical 3x3 pano from a drone, you'll have to do this 9 times.

(2) In the panorama editor, go to HDR exposure, change "reference" to brightest exposure

Ideally, PT Gui would see that nearly identical frames have exposure compensation and link them and then set the reference automatically to avoid clipping when working with HDR content.

The power of PT Gui to manage complex stitches involving HDR is awesome, but the workflow is tedious and won't be intuitive for most users.

[PTGui Support]

That's just not correct; it works like this:

Load all your bracketed images
Press Align Images
PTGui tells you it found x sets of y bracketed exposures, Would you like
to link them and create an HDR panorama? -> Click OK.

It doesn't get easier than this.

The above will fail only if your bracketing is irregular, or if it's a
single bracketed frame (not a panorama). In that case you can do: Images
-> Link Bracketed Exposures and tell PTGui how many brackets per frame
you have.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[Greg Benz]

Thank you for the info, Joost. I've been trying more difficult stitches and must have run into that limitation.

To clarify with the various discussion here, the only critical issue here is be getting the DNG output to match the quality of the source (issue #3).

I still believe it would be ideal for the HDR output to automatically avoid any clipping, but that's relatively minor as the user can work around that with the guidance you provided to change the reference exposure.

I appreciate your efforts here. My ultimate goal is to recommend and demonstrate PT Gui for HDR panos to my audience once I'm able to get a workflow for RAW output.