Preserving Exif metadata in the PTGui output

[Velson Horie]

This is probably not the first such request.

My panoramas are from mosaics of flat paper prints, which are stitched from tiles with the same dpi, bit depth, focal length, magnification etc, and hopefully produce a panorama with very similar properties.

However in rectilinear stitching 2 images into one, the metadata of the files changed from

600 to 300 ppi (the originals are actually 1417 ppi, but I forgot to adjust it in those 2 files)

48 to 64 bit dept

120 to 1396 mm focal length

How can the metadata from the source images be preserved and reproduced in the PTGui created Exif?

These panoramas will be used to measure the size of features on the images, so it would be useful if the dpi reflected the reality and scale of the source images. I shall have to do some tests to check if, or by how much, the internal dimensions of the PTGUI stitched image matches those of the source images. A crude first measurement suggests that the PTGui image is ca 0.5% smaller than the original, but that is near the precision of this measurement.

It would also be useful (if possible) for the new PTGui Exif to list the images used to create the panorama. I realise that the Exif specifications are inelastic (sometimes I use hundreds of original images in one panorama)

Thank you

[PTGui Support]

Hi Velson,

You can change the dpi setting in the Metadata tab. Switch PTGui to
Advanced mode if you don't see it.

The bit depth is a property of the output format. If you remove the TIFF
alpha channel (see the Settings button in the Create Panorama tab)
you'll have 3x16=48 bits, but obviously you'll loose the transparency.
With alpha channel included you'll get 4x16=64 bits.

The focal length is not meaningful for scanned images, but currently
PTGui will always add it if the lens is set to rectilinear.

I'm not sure if I understand your remark about the internal dimensions,
but you can always adjust the size of the stitched image in the Create
Panorama tab.

Adding the names of the source images to the metadata is not supported,
I'm sorry.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[Velson Horie]

1. Metadata.  I have looked at the metadata provided in the original image file with that relayed by PTGui.

As seen on Photoshop e.g.

" <aux:SerialNumber>JD011012</aux:SerialNumber>
         <aux:LensInfo>0/1 0/1 4/1 32/1</aux:LensInfo>
         <aux:Lens>Schneider Kreuznach Macro LS 120mm f/4.0</aux:Lens>
         <aux:LensSerialNumber>TD003205</aux:LensSerialNumber>
         <aux:ImageNumber>59762</aux:ImageNumber>
         <aux:ApproximateFocusDistance>1512/1000</aux:ApproximateFocusDistance>
         <aux:Firmware>IQ4 150MP, v8.02.0 (FWP)</aux:Firmware>"

 and reported in the PTGui Lens settings

But according to the Photoshop tool, these data are not included in the PTGui output file.

I think they should be.  For instance, it is iinteresting when using the CP window to see the fall-off of resolution from centre to edge, even of this excellent lens.

2. ppi settings.  I have just replaced the ppi settings in 100 image files provided to me by someone who had used this camera's default setting of 600, when the measured value was ca 366.  It would be good if PTGui could take the settings from the (revised) input file metadata and repeat them in the output file.

3.  Focal length. PTGui calculates a focal length that is useful for the best processing of the images to a panorama. However the focal length of the original lens is still useful information.

TIFF. I often wondered what the transparency setting did.  Nothing useful for me, so I have unset it.

4. Internal dimensions.  I was testing to see if the size of features changed during the process of blending from the original images to the stitched composite.  In rectiliear mode, no change of size seems apparent.

Thank you

Velson

[PTGui Support]

Hi Velson,

I disagree; the metadata should correspond to the actual image. Once the
image is stitched, it's could be as if it's take with a wider angle (say
30mm) lens. Adding metadata for a 120mm lens to such a panorama would be
wrong IMO, it may cause problems if the stitched image is loaded in
other applications.

Perhaps PPI can be calculated automatically as you suggest, I'll add
this to the wish list. It's meaningless for regular stitched panoramas
but I guess for your kind of scanned images this is useful.

Adding additional metadata support is on the wish list though. A comment
field might be useful where you can add any necessary information.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 5/26/23 12:55, Velson Horie wrote:
> 1. Metadata.  I have looked at the metadata provided in the original
> image file with that relayed by PTGui.
> As seen on Photoshop e.g.
> " <aux:SerialNumber>JD011012</aux:SerialNumber>
>          <aux:LensInfo>0/1 0/1 4/1 32/1</aux:LensInfo>
>          <aux:Lens>Schneider Kreuznach Macro LS 120mm f/4.0</aux:Lens>
>          <aux:LensSerialNumber>TD003205</aux:LensSerialNumber>
>          <aux:ImageNumber>59762</aux:ImageNumber>
>
>  <aux:ApproximateFocusDistance>1512/1000</aux:ApproximateFocusDistance>
>          <aux:Firmware>IQ4 150MP, v8.02.0 (FWP)</aux:Firmware>"
>
>  and reported in the PTGui Lens settings

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

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[Erik Krause]

Am 27.05.2023 um 13:36 schrieb 'PTGui Support' via PTGui Support:
> I disagree; the metadata should correspond to the actual image. Once the
> image is stitched, it's could be as if it's take with a wider angle (say
> 30mm) lens. Adding metadata for a 120mm lens to such a panorama would be
> wrong IMO, it may cause problems if the stitched image is loaded in
> other applications.

Velson, if you want the metadata copied exactly from the input images to
the output image, I suggest you write a small shell script calling
exiftool. Depending on your directory structure and naming conventions,
it can do this automatically or by drag and drop.

You can even register it as a "Viewer" in PTGui (via
Tools->Options->Viewers). This is also possible with a droplet created
by photoshop. For this you would need to record what you want to do as
an action in photoshop and create a droplet from this action. A droplet
is a normal executable which can be used as a "Viewer".

--
Erik Krause
http://www.erik-krause.de

[Velson Horie]

Look at Mike's page

https://speleotrove.com/gallery/Kenilworth_Castle.html

each of his images is accompanied by extensive valuable metadata. 

Photos, physical or digital, easily lose their metadata, on paper labels or the online documentation -   once lost they cannot be recovered.  So I now try to make each file self documenting, which means recording and adding each step into Exif.

So while considering the metadata upgrade, could you append to the comment field (or similar) significant metadata that would be lost or overwritten during PTGui processing?

The difference in quality and inclusion from different imaging systems is significant when examining and using panoramata etc.  Increasingly, these derivative images will be used as archival evidence from the digital world, so how they were derived should be part of the audit trail.

Velson

[Mike Cowlishaw]

Hi Velson,

The Exif data in the images you refer to [except the one from 2015] are unchanged from those provided by PTGui.  The additional information under  each image I extracted from one of the original images (which nowadays I always keep) or from my notes.  I agree with you that that original information is useful and important, but I also agree with Joost and Erik that the stitched panorama should reflect the 'effective lens used'.

PanGazer has a  setting that overlays a grid on images whose lens 'length' is known (this is currently a test setting at the moment) and this would be mightily confused and just plain wrong if the stitched image sported the lens length of one of the original images.

A lot can be done with a good directory (folder) organisation.  I use a somewhat primitive one:

• For each 'shoot' I have a top directory, named and dated (e.g., Kenilworth-Castle-20230503)
• Any written notes are transcribed to a text file in that directory, using the same name (e.g.,  Kenilworth-Castle-20230503.txt)
• Within this is a sub-directory for each panorama (named, for example, KC-A, for 'ordinary' panoramas, or as named by the drone for DJI spherical panoramas, etc.)
• When I stitch the panoramas the result goes into the top directory (i.e., the parent of the original data directory) with a name derived from the data directory (e.g., KC-A-pan.jpg).  I use that suffix '-pan' to identify 'wide' images for various purposes.
  

The net result is a directory with all the panoramas and relevant notes, together with a sub-directory for each panorama with the original images (and only the original images, so they can easily be selected to restitch, batch process, zip to send somewhere. etc.).  


Mike