PTGui HDR Masking

[Kuba Piwowarczyk]

Hi all, 

I recently purchased PTGui 12 Pro and have run into something I cannot figure out how to do. 

When combining an HDR panorama, I have some clear ghosting as there were some people moving within the frame. 

Things I have tried:

- I am of course able to mask linked images as a whole, but I have not found a way to mask in or out a single image out of the linked set. 

- I have found the option to simply exclude entire images from the linked set, however, this is not ideal as that would cause me to lose dynamic range in the rest of the photo. 

- Another workaround is to simply add a duplicate of the image I would like to mask in as a single image (not a bracketed HDR exposure) and then mask it in. But this is tedious and annoying as I don't want to have a duplicate of nearly every image just for this.

Ideally, I would like to have a seamless way to mask images within an HDR bracketed set, so I can manually remove the ghosts.

Is there currently any way to do this nicely? Or is this a wishlist feature?

Thanks in advance!

[John Houghton]

On Tuesday, October 4, 2022 at 12:30:34 AM UTC+1 Kuba Piwowarczyk wrote:

- I am of course able to mask linked images as a whole, but I have not found a way to mask in or out a single image out of the linked set. 

Kuba, when you have loaded in the images, PTGui will say "bracketed exposures detected" and you then click on the enable HDR mode link. Choose the second option it then offers.  You can then mask individual images in a particular bracketed set.  On the Image Parameters tab, you should then link the images in the other bracketed sets.

Also see PTGui FAQ: https://ptgui.com/support.html#7_5 and #7.6.

John

[PTGui Support]

This may work in some cases but it can also lead to new image artifacts
near the edges of the masks you have painted. PTGui doesn't have a good
deghosting solution for HDR currently.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[Kuba Piwowarczyk]

John, 
Thanks for your response. I tried your mentioned method, however, even though I am able to mask individual images in the bracketed set, PTGui still blends in a similar way and creates ghosting. It seems PTGui ignores red masks within a bracketed set if other areas are marked green and just blends to HDR as normal. I have tried this with both HDR workflow options.

Joost, 
Thanks for your insight. And ah, that's unfortunate. I guess I will have to stick to my workaround for now. 
Would it be possible to add this to the wishlist? 

Perhaps I am missing some intricacy, but it seems like it might be possible to implement by either:
- Enforcing red masks in a stricter way that can allow only a single image to be used in the final HDR blend in a given area (similar to excluding a single image from a bracketed set from a panorama, but only in the masked area)

- Adding in a new "anti-ghost" brush, in which PTGui would automatically choose the best frame to take pixels from in the area to maximize dynamic range and reduce artifacts. 

     - Ghosting could also likely be detected within the masked region by calculating the discrepancy from the camera response curve across the bracketed set. Then the anti-ghosting measures would only be performed on these pixels. This might allow the spread of any artifacts in the region to be minimized.

Thanks again,

Kuba

[John Houghton]

On Tuesday, October 4, 2022 at 10:05:15 AM UTC+1 Kuba Piwowarczyk wrote:

John, 
Thanks for your response. I tried your mentioned method, however, even though I am able to mask individual images in the bracketed set, PTGui still blends in a similar way and creates ghosting. It seems PTGui ignores red masks within a bracketed set if other areas are marked green and just blends to HDR as normal. I have tried this with both HDR workflow options.

Kuba, well, I did a test with an artificially created shift of an object in the ev0 image (of 3 brackets).  This was masked out in that image, and green masks applied to roughly the same area in both the ev1 and ev-1 images (though this is not necessary). The masked version is good (on the right).  So, I would say that the method basically does work, but as Joost warns, there may well be artifacts in some cases.

John

[Kuba Piwowarczyk]

Hi John, 

Thanks for that demo. I've tried to replicate the same on my image.

Here is a sample crop of my original image with ghosting:

Here is the result if I bracket but unlink the set and green mask one frame and red mask the others (similar areas just like you did). Note that PTGui insists on pulling data from other overlapping frames, effectively ignoring my green mask, so I had to exclude all overlapping frames from the panorama (not ideal). You can see a clear artifact where PTGui failed to blend the images correctly.

Now, here is my workaround method: I duplicate one of the frames from the bracketed set and leave it as a single image, whereas the rest of the images are bracketed and linked. I green mask from only the single lone image. No artifacts or ghosting and PTGui actually respects my green mask. Tedious as I need to duplicate every image with a person, but seemingly effective.

Ideally, my way and your way should produce the same results. However, they do not. There is either something going on behind the scenes in PTGui which is not intuitive or it is simply a bug.

Let me know what you think,

Kuba

[John Houghton]

Kuba, the results of your tests are interesting.  No doubt any artifacts that develop will be affected by the precise size and shape of any masks that are applied.  I rarely use HDR processing myself.  On one occasion when I encountered ghosting, I resorted to editing the ev+2 and ev-2 images by generating fake images from the ev0 image (brightened and darkened respectively to match) and patching over the offending ghost features.  That worked perfectly.

John

[Erik Krause]

Am 04.10.22 um 22:47 schrieb Kuba Piwowarczyk:

> Ideally, my way and your way should produce the same results. However, they
> do not. There is either something going on behind the scenes in PTGui which
> is not intuitive or it is simply a bug.

The results are probably different, because two different processes are
used. Between images of a bracketed set, HDR merging is used, while
between images that make up a panorama blending is used. While blending
is optimized to leave no visible seams, HDR merging tries to use the
best exposed pixels from each image (generally speaking).

--
Erik Krause

[Idociofoto]

Kuba, I find your workaround very interesting, but it's hard for me to understand exactly the process (my English is not native and I must not be understanding well some part of the translation).

Could you add some extra screenshots accompanying the description of the process?

Thank you

[Marco Schwaer]

soo, view days passed by: Any Updates here? Currently I'm Facing the same problem: Group of persons in water while sunset with 5 AEB. 0 would be fine for the group, but due to HDR Merge/exposure fusion ghosts are created.

Grouping HDR ("Handheld" does not solve that - not even a far workaround - at least for me)

I'm on PtGUI 12.21 now.

[PTGui Support]

You could try removing the other 4 brackets for that particular frame.

PTGui Pro 12 can create HDR from inconsistent bracketing sequences. In
the Exposure/HDR tab ensure that 'HDR workflow: merge bracketed images
to HDR, then blend'.

If you do this you should probably use one of the darker frames, to
ensure that there are no clipped highlights.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

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[PTGui Support]

Hi Marco,

Have you tried removing the 4 other bracketed images for this particular
shot? This would probably work, assuming you are using PTGui 12 or later.

Kind regards,

Joost Nieuwenhuijse
www.ptgui.com

On 16-06-2023 09:59, 'Marco Schwaer' via PTGui Support wrote:

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