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image alignment/registration

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image alignment/registration Casey Connor 05 Feb 02:57
  image alignment/registration Pat David 05 Feb 23:21
   image alignment/registration oneaty 19 Mar 12:25
    image alignment/registration Casey Connor 20 Mar 22:35
     image alignment/registration oneaty 24 Mar 19:58
      image alignment/registration Casey Connor 24 Mar 22:00
       image alignment/registration oneaty 24 Mar 22:36
        image alignment/registration oneaty 24 Mar 22:42
        image alignment/registration Casey Connor 24 Mar 23:02
         image alignment/registration oneaty 25 Mar 00:17
          image alignment/registration Casey Connor 25 Mar 00:41
           image alignment/registration oneaty 25 Mar 10:18
            image alignment/registration Casey Connor 25 Mar 16:52
Casey Connor
2017-02-05 02:57:03 UTC (about 1 month ago)

image alignment/registration

Hi - I was curious what the best overall image alignment plugin/method in GIMP (or out of GIMP) was these days?

"Best" for me means "most powerful/flexible/option-rich".

I've come across the hugin align_image_stack, the G'MIC plugin's "Align layers" option, and the image registration plugin . (I've also used the "Exact
Aligner" script, but it's two layers only.)

The goal is to align and then use mean/median for noise reduction stacking. I'll probably be working in 16bit.

Do all three methods do sub-pixel alignment? I read someone on pixls.us suggesting that the user upscale the source images by up to 1.33x before aligning for the sake of effectively achieving sub-pixel alignment, but if the current alignment methods do that anyway, seems like I should skip it... ?

Thanks!

-c

Pat David
2017-02-05 23:21:11 UTC (about 1 month ago)

image alignment/registration

Align_image_stack is usually the best option other than possibly attempting it manually directly in Hugin.
On Sat, Feb 4, 2017 at 8:57 PM Casey Connor wrote:

Hi - I was curious what the best overall image alignment plugin/method in GIMP (or out of GIMP) was these days?

"Best" for me means "most powerful/flexible/option-rich".

I've come across the hugin align_image_stack, the G'MIC plugin's "Align layers" option, and the image registration plugin . (I've also used the "Exact
Aligner" script, but it's two layers only.)

The goal is to align and then use mean/median for noise reduction stacking. I'll probably be working in 16bit.

Do all three methods do sub-pixel alignment? I read someone on pixls.us suggesting that the user upscale the source images by up to 1.33x before aligning for the sake of effectively achieving sub-pixel alignment, but if the current alignment methods do that anyway, seems like I should skip it... ?

Thanks!

-c

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Pat David
GPG: 66D1 7CA6 8088 4874 946D  18BD 67C7 6219 89E9 57AC
2017-03-19 12:25:37 UTC (6 days ago)
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image alignment/registration

Align_image_stack is usually the best option other than possibly attempting
it manually directly in Hugin.
On Sat, Feb 4, 2017 at 8:57 PM Casey Connor

wrote:

I tried align_image_stack many times, using different options combinations, but coudn't get aligned images in the end. I'm trying to abandon PS and fully use gnu software, but, so far, couldn't find a decent replacent for PS's autoalign feature. The point is that I didn't use tripod, so there are alignment differences in the original frames. PS's autoalign can handle that situation in a very satisfactory manner. Am I missing something?
I don't want to piggyback Casey's post, but since I have the same question, I choose to put this post here. If admins feel I should open another thread, just let me know.

Casey Connor
2017-03-20 22:35:24 UTC (5 days ago)

image alignment/registration

I tried align_image_stack many times, using different options combinations, but coudn't get aligned images in the end.

Per recommendations here, I've used it and it worked really well; I've read, and experienced, that it seems to need images to be pretty close already. Meaning, by default it won't assume the images should be aligned a great distance, so if you moved much while shooting it might not work out. You might investigate the -g option -- I'm not totally clear on how it works, but it sounds from the description like it might change the scale which align_image_stack uses to find control points. Maybe also the -t option?

You could also check out hugin, which AFAIK uses align_image_stack under the hood to do its alignment. It allows all kinds of manual intervention/editing of control points. I understand that a "one-click" solution is ideal, but mention it just in case. You can at least visually see what's happening with the control points and understand better where things are going wrong.

-c

2017-03-24 19:58:02 UTC (1 day ago)
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Per recommendations here, I've used it and it worked really well; I've read, and experienced, that it seems to need images to be pretty close

Thanks for the feedback.
I believe if I shoot with a tripod it would work fine. The point is that a tripod isn't an option to me most of the time. My only camera is an old point & shoot Canon A3100, boosted by CHDK. CHDK has many wonderful features, but the one I mostly use is its raw capability, not available on Canon original firmware. Besides, I usually do a lot of stacking, pushing the final image quality to its limits. And here is my problem.
With PS, I can auto align hand held shots with excellent results. The differences in perspective between shots do exist but are not big, because I try to hold the camera the most steadier I can when shooting. I just came from aligning the same set of pictures in PS I tried in Hugin, and it worked almost perfectly. Before that, I had also tried using JImage (and its full package FiJi), but it is really, really complex and I gave up. So, unfortunately (being an open source fan), I will still have to keep with PS, until I find an open source alternative to its auto alignment feature.

Casey Connor
2017-03-24 22:00:46 UTC (about 24 hours ago)

image alignment/registration

Did you try the -g option with align_image_stack? Or -t?

I align hand-held images with align_image_stack and it works fine, even without those options... e.g. this one: https://www.flickr.com/photos/lacinato/32628735771/in/dateposted-public/

-c

On 03/24/2017 12:58 PM, oneaty wrote:

Per recommendations here, I've used it and it worked really well; I've read, and experienced, that it seems to need images to be pretty close

Thanks for the feedback.
I believe if I shoot with a tripod it would work fine. The point is that a tripod isn't an option to me most of the time. My only camera is an old point & shoot Canon A3100, boosted by CHDK. CHDK has many wonderful features, but the one I mostly use is its raw capability, not available on Canon original firmware. Besides, I usually do a lot of stacking, pushing the final image quality to its limits.
And here is my problem.
With PS, I can auto align hand held shots with excellent results. The differences in perspective between shots do exist but are not big, because I try to hold the camera the most steadier I can when shooting. I just came from aligning the same set of pictures in PS I tried in Hugin, and it worked almost perfectly.
Before that, I had also tried using JImage (and its full package FiJi), but it is really, really complex and I gave up. So, unfortunately (being an open source fan), I will still have to keep with PS, until I find an open source alternative to its auto alignment feature.

2017-03-24 22:36:29 UTC (about 23 hours ago)
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Did you try the -g option with align_image_stack? Or -t?

I align hand-held images with align_image_stack and it works fine, even
without those options... e.g. this one: https://www.flickr.com/photos/lacinato/32628735771/in/dateposted-public/

-c

Tried

align_image_stack -a *.tif

and

align_image_stack -a -g *.tif

and no success...

2017-03-24 22:42:41 UTC (about 23 hours ago)
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Tried

align_image_stack -a *.tif

and

align_image_stack -a -g *.tif

and no success...

The whole process:

1 - Shoot in DNG 2 - RawTherappe - Open dng's with preset Neutral and save them as tif 3 - align_image_stack.

Btw, beautiful image.

Casey Connor
2017-03-24 23:02:51 UTC (about 23 hours ago)

image alignment/registration

So, backing up a step: when you say align_image_stack doesn't work, what do you mean exactly? I assumed you meant that it did a poor job aligning the images, but I don't think the command lines you list there would even work to start the program, so I'm wondering now if you meant that it doesn't even run?

"-a" requires a prefix following it, and "-g" requires a number.

E.g.:

align_image_stack -a someprefix -g 8 *.tif

Documentation is here: http://wiki.panotools.org/Align_image_stack

2017-03-25 00:17:13 UTC (about 21 hours ago)
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So, backing up a step: when you say align_image_stack doesn't work, what
do you mean exactly? I assumed you meant that it did a poor job aligning
the images,

Correct assumption,

but I don't think the command lines you list there would

even work to start the program, so I'm wondering now if you meant that it doesn't even run?

"-a" requires a prefix following it, and "-g" requires a number.

E.g.:

align_image_stack -a someprefix -g 8 *.tif

Documentation is here: http://wiki.panotools.org/Align_image_stack

Well, it works.

-a without explicit prefix defaults to the name of the first image file given.

-g without explicit number defaults to 5 (that is written in the --help option)

Btw, what os are you using?

I'm running this on Linux (Ubuntu 16.04)

Casey Connor
2017-03-25 00:41:54 UTC (about 21 hours ago)

image alignment/registration

Ah, ok. So what exactly goes wrong: one or two of the images is off-kilter?

If you specify -g, try using something besides the default, as I'm not sure that using the default will change the behavior. (Meaning, not specifying -g probably results in the same thing as just "-g" -- the documentation is a little unclear, but I assume it's active when not specified.) Perhaps try -g 3 or 4 instead? I'm not 100% sure how to interpret it. If that doesn't work, try 6 or 7?

Btw, what os are you using?

Kubuntu 16.10.

-c

2017-03-25 10:18:26 UTC (about 11 hours ago)
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Ah, ok. So what exactly goes wrong: one or two of the images is off-kilter?

Yes, that's it. I'm just checking the first two images, since PS successfully aligned all of them.

If you specify -g, try using something besides the default, as I'm not sure that using the default will change the behavior. (Meaning, not specifying -g probably results in the same thing as just "-g" -- the documentation is a little unclear, but I assume it's active when not specified.) Perhaps try -g 3 or 4 instead? I'm not 100% sure how to interpret it. If that doesn't work, try 6 or 7? Kubuntu 16.10.

-c

I tried

align_image_stack -a align -g 10 -t 5 *.tif

and

align_image_stack -a -dixyz *.tif

and

align_image_stack -a align -SAP *.tif

and the images (the first two) are still unaligned

The resulting stack by using Photoshop can be seen here https://flic.kr/p/SDKdBf

Casey Connor
2017-03-25 16:52:15 UTC (about 5 hours ago)

image alignment/registration

I tried

align_image_stack -a align -g 10 -t 5 *.tif

Did you try with a lower-than-default -g? E.g. "-g 3"?

If you want to upload the base .tif files somewhere, I can try to align them, so we can see if there is some strange difference between align_image_stack on our machines.

-c