DNG output needs improvements (missing profiles, metadata issues, compression)

[cppasm]

Hi.

There was related issue published already, but no solution provided:
DNG Output Adobe Profiles missing

So I'll do my best to describe issues, why it matters and results of my investigation.

Objectives:

Why Panorama stitching to DNG in Adobe software became popular?
Because it allows to stitch RAW files into DNG pano and get exactly the same color rendition as original RAW photos, including camera matching profiles.
This allows to stitch, and then edit one single image, as opposed to edit parts and stitch afterwards.

And it would be great to have this in PTGui, but unfortunately it's not there yet.

Issues:

1. No RAW and camera matching profiles for DNG from PTGui in ACR/LrC.
File partially acts as RGB TIFF image - only available options are "Color" and "Black and White".

2. No previews in Adobe Bridge for PTGui DNG and unable to zoom to 100% (full sized preview unavailable)

3. Relatively big DNG files from PTGui as they are completely uncompressed.

Observations/ways to improve:

1. Profiles are missing due to metadata.

Generated DNG files have EXIF:UniqueCameraModel="PTGui DNG" which causes profiles to be unavailable in ACR/LrC.
If I set this tag to be equal to CameraModel from original RAW files I get all RAW and Camera matching profiles back in ACR/LrC, but this creates another huge issue.
This would work if PTGui only demosaic and stitch images without altering RAW data, and this obviously is not the case becase color rendition gets broken - image colors became heavily shifted into pink.
Looks like channels have been rebalanced or WB was applied already, or something along that lines.

Also changing Camera Model by adding square brackets may be not greatest idea also.
Adobe doesn't care, but some other software might.
I would say that this at least should be optional.

2. Missing previews are also caused by metadata structure.
After export from PTGui preview in Adobe Bridge looks like random stripes.
But if I use exiftool to make some changes which actually don't change anything (Camera Make is already Canon) I got this:

>exiftool "-Exif:Make=Canon" IMG_0001-PTGui-Fix.dng                                                    Warning: [minor] Oversized SubIFD TileByteCounts (209284866 bytes, but expected 206531628) -  IMG_0001-PTGui-Fix .dng                        1 image files updated        

And after this preview and 100% viewing works without any issues.

3. Compression.
Well it would be nice to have output DNG compressed.
But that's really a minor issue, as it's possible to convert from DNG to DNG using Adobe DNG Converter or other Adobe software like Bridge+ACR/LrC and get those files compressed afterwards.

What are your thoughts on this?
Is it possible to implement some of this and improve interoperability with Adobe software?
For me personally getting back profiles would be top priority, as everything else could be fixed by converting DNG to DNG in software like Adobe DNG Converter.

Having all those projections that PTGui has available and getting same color rendition for DNG as for original RAW files would already surpass what Adobe is currently capable of doing in terms of pano stitching.

If I can help with anything to increase chances and make this happen - just let me know.

 
Regards.

[John Friend]

This is quite unfortunate.  If the color profile and/or white balance is already applied, then I'm unsure how this new DNG is actually advantageous over a 16-bit TIFF.  It would really just be a TIFF in a DNG container, wouldn't it.  In fact, since TIFFs can be compressed and these DNGs are not, perhaps its even worse than a TIFF.  What would the advantages of this type of DNG be over a 16-bit TIFF?  Any?

And, here I was thinking this would be the feature to push me to upgrade to v13, but perhaps not.

[PTGui Support]

Hi,

Are you working with DNG source images, or RAW files?

With DNG source images you'll get the best results. The output will be
in the original source DNG color space. PTGui will also keep the
original embedded processing profiles, such as those embedded by DJI
drones. ACR will show the original camera's processing profiles. The
results in my tests look nearly identical to the source DNG files; if
you find this not to be the case I'd be happy to receive a set of images.

For RAW source images it's less perfect. PTGui uses libraw to parse the
images and it does a color space conversion to linear ProPhoto.
Considering the many different raw raw formats I haven't been able to
avoid this. Linear ProPhoto has a wide enough gamut so it doesn't cause
any color changes. White balance is also kept original. But the raw
converter cannot rely on the known profiles of the source camera, so
that's why UniqueCameraModel is not set.

If you are currently CR2 files, please give it try by converting to DNG
first and stitch those.

Nevertheless, the DNG files created by PTGui are not raw files: PTGui
will need to demosaic and linearize the source images prior to
stitching. This is unavoidable, and it also applies to DNG panoramas
created by Photoshop for example. I guess you were aware of this but I
should mention it.

I will look into the TileByteCount and see if this is a bug. Adding
compression and including a full size jpeg thumbnail is on the wish
list. And I'll see if it's possible to preserve the RAW color space and
make ACR profiles work not just for DNG->DNG but also for RAW->DNG workflow.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 9/10/25 21:55, cppasm wrote:
> Hi.
>
> There was related issue published already, but no solution provided:

> DNG Output Adobe Profiles missing <https://groups.google.com/g/ptgui/c/
> SGZHi0uJdZk>

>
> So I'll do my best to describe issues, why it matters and results of my
> investigation.
>
> Objectives:
>
> Why Panorama stitching to DNG in Adobe software became popular?
> Because it allows to stitch RAW files into DNG pano and get

> *exactly* the same color rendition as original RAW photos, including

> --
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> groups.google.com/d/msgid/ptgui/bf13479d-730d-4326-
> affd-175bfb0d7584n%40googlegroups.com?utm_medium=email&utm_source=footer>.

[PTGui Support]

Hi John,

For one, the DNG can be processed in Adobe Camera RAW, so you can
postpone ACR edits to the finished panorama instead of doing those on
each individual source image. Especially for local corrections like
shadow/highlight, this is better, because panoramic blending is ideally
done on linear unprocessed source images.

I suggest you give it a try in the trial version and see if it's a
benefit to your workflow.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 9/11/25 04:31, John Friend wrote:
> This is quite unfortunate.  If the color profile and/or white balance is
> already applied, then I'm unsure how this new DNG is actually
> advantageous over a 16-bit TIFF.  It would really just be a TIFF in a
> DNG container, wouldn't it.  In fact, since TIFFs can be compressed and
> these DNGs are not, perhaps its even worse than a TIFF.  What would the
> advantages of this type of DNG be over a 16-bit TIFF?  Any?
>
> And, here I was thinking this would be the feature to push me to upgrade
> to v13, but perhaps not.
>
> On Wednesday, September 10, 2025 at 12:57:15 PM UTC-7 cppasm wrote:
>
> Hi.
>
> There was related issue published already, but no solution provided:

> DNG Output Adobe Profiles missing <https://groups.google.com/g/
> ptgui/c/SGZHi0uJdZk>

>
> So I'll do my best to describe issues, why it matters and results of
> my investigation.
>
> Objectives:
>
> Why Panorama stitching to DNG in Adobe software became popular?
> Because it allows to stitch RAW files into DNG pano and get

> *exactly* the same color rendition as original RAW photos, including

> --
> You received this message because you are subscribed to the Google
> Groups "PTGui Support" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to ptgui+un...@googlegroups.com
> <mailto:ptgui+un...@googlegroups.com>.
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> groups.google.com/d/msgid/ptgui/692b1caf-eacc-4826-
> b144-6ae17855b4f8n%40googlegroups.com?utm_medium=email&utm_source=footer>.

[John Friend]

I'm using Capture One, not Adobe products so I'm looking for a format that imports well into Capture One.  My source images are Nikon Z7ii RAW files.  Capture One has only partial DNG support so I don't know if the PTGui DNG files would work or not.  The Capture One DNG support is really just for a few cameras that natively produce DNG files and for the DNG files that Capture One generates themselves (from their own pano or HDR merging).  As an example of their partial support, they don't read color profiles from a DNG which I guess is irrelevant for DNGs output from PTGUI because they are already color converted to the ProPhoto color space.

What are the advantages of your output DNG output over a 16-bit TIFF output?  If they are already demosaiced and color profile and white balance already applied, then I'm confused as to how a DNG would be any better/different than a 16-bit TIFF file?  At that point, it sounds like it's just a ProPhoto 16-bit TIFF in a DNG container.

[PTGui Support]

DNG actually is a TIFF file by specification. It's an extension of TIFF
with custom tags. It's not limited to camera raw data; Adobe also uses
it for demosaiced output like panoramas.

The DNG produced by PTGui is similar to a linear HDR tiff file like you
would get from PTGui's HDR panorama output. White balance is kept
original, no curves are applied. This is all required to get a good
looking image from sensor data. Normally this is done during raw
conversion.

By outputting to DNG you postpone these steps to the stitched panorama,
instead of doing them before stitching. Especially local corrections
like shadow/highlight give better results when done after stitching.

For Adobe users, DNG files give you convenient access to Camera Raw
whereas linear TIFF does not. I don't know about C1, but at least it
should support the DNG files from PTGui.

Whether this is useful in your workflow is something only you can decide!

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 9/11/25 11:17, John Friend wrote:
> I'm using Capture One, not Adobe products so I'm looking for a format
> that imports well into Capture One.  My source images are Nikon Z7ii RAW

> files.  Capture One has partial DNG support so I don't know if the PTGui

> DNG files would work or not.  The Capture One DNG support is really just

> for a few cameras that natively product DNG files and for their own
> generated DNG files (from their own pano or HDR merging).  For example,
> they don't read color profiles from a DNG (which I guess is irrelevant

>
> What are the advantages of your output DNG output over a 16-bit TIFF
> output?  If they are already demosaiced and color profile and white
> balance already applied, then I'm confused as to how a DNG would be any
> better/different than a 16-bit TIFF file?  At that point, it sounds like

> a TIFF in a DNG container.

>
> On Thursday, September 11, 2025 at 12:48:54 AM UTC-7 PTGui Support wrote:
>

> Hi John,
>
> For one, the DNG can be processed in Adobe Camera RAW, so you can
> postpone ACR edits to the finished panorama instead of doing those on
> each individual source image. Especially for local corrections like
> shadow/highlight, this is better, because panoramic blending is ideally
> done on linear unprocessed source images.
>
> I suggest you give it a try in the trial version and see if it's a
> benefit to your workflow.
>
> Kind regards,
>
> Joost Nieuwenhuijse

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

> <https://groups.google.com/d/msgid/>
> > ptgui/692b1caf-eacc-4826-b144-6ae17855b4f8n%40googlegroups.com
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> > b144-6ae17855b4f8n%40googlegroups.com?
> utm_medium=email&utm_source=footer <http://40googlegroups.com?
> utm_medium=email&utm_source=footer>>.

>
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[cppasm]

Hi Joost,

Thanks a lot for your prompt responce - it really helped a lot!
Yes, everything that I've wrote was about using original RAW as inputs (CR2 in my case).
Converting to DNG and using those as inputs made a huge difference - it then works exactly as I wanted including color rendition and profiles availability.
Maybe consider adding information that DNG workfow is preferable to the FAQ, as it's not that evident.

Also, I do understand that output DNG is not a "true" RAW as it was already demosaiced and linearized - that is fine and expacted.

>  What are the advantages of your output DNG output over a 16-bit TIFF output?

As far as I know - PTGui does not have linear TIFF as output format.
For regular 16-bit TIFF files gamma curve has been applied already - this limits tonal range udjustments (not much from practical standpoint).
For linear DNG it is possible to set WB in Kelwins, while for TIFFs (both linear and gamma-corrected) it is not.

>  For Adobe users, DNG files give you convenient access to Camera Raw whereas linear TIFF does not. I don't know about C1, but at least it should support the DNG files from PTGui.

Actually it is possible to open linear TIFF in Camera RAW (and even non-linear too).
The main practical difference is that for DNG it is possible to adjust WB in Kelvins (and this works for DNG from PTGui), while for TIFFs it's only on the wormer/cooler scale.

[PTGui Support]

You get linear TIFF from PTGui's HDR output. If you check the "HDR
Panorama" box in Create Panorama and choose TIFF, this will generate a
32 bit/channel floating point panorama with a linear color profile.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

[PTGui Support]

John, by the way, let me add that you can safely install the v13 trial
version next to your current older version, see 3.29:
https://ptgui.com/support.html#3_29

If you accidentally overwrite your current PTGui, you can always
re-download it from your account:
https://www.ptgui.com/account

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com