Problems with exposure compensation

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Greg 'groggy' Lehey

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Mar 19, 2014, 7:02:09 PM3/19/14
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I have a strange problem with a panorama I took the other day. I've
attached a small version, and you can see it in larger sizes at
http://www.lemis.com/grog/photos/Onephoto.php?image=/grog/Photos/20140317/Apostles-panorama-2.jpeg

The problem that concerns me at the moment is that the cliffs on the
right are seriously underexposed, although the original image covering
that part of the panorama is relatively well exposed.

I can't find any knob in hugin to do this kind of compensation. In
the assumption that enblend is looking at the actual exposure in the
EXIF, I've tried tweaking the EXIF to lie about the exposure, but to
no avail. If anybody wants to take a look, I've put the images in 25%
size at http://wwww.lemis.com/grog/tmp/00.jpeg to
http://wwww.lemis.com/grog/tmp/08.jpeg (a total of 8 MB). Contact me
if you'd like to see the originals. There's also a pto file at
http://wwww.lemis.com/grog/tmp/Apostles-panorama-2.pto, but it's just
what cpfind creates, and doesn't include the tuning I did for the
"final" panorama.

So, my question: how do I lighten the cliffs on the right? Does hugin
provide something to do that? Is there a way to trick it into doing
so?

Greg
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Apostles-panorama-2.jpeg

Terry Duell

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Mar 19, 2014, 7:46:20 PM3/19/14
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Hello Greg,

On Thu, 20 Mar 2014 10:02:09 +1100, Greg 'groggy' Lehey
<groo...@gmail.com> wrote:

[snip]

> If anybody wants to take a look, I've put the images in 25%
> size at http://wwww.lemis.com/grog/tmp/00.jpeg to
> http://wwww.lemis.com/grog/tmp/08.jpeg (a total of 8 MB).

One too many w's, but I managed to get the small images.

> Contact me if you'd like to see the originals. There's also a pto file
> at
> http://wwww.lemis.com/grog/tmp/Apostles-panorama-2.pto, but it's just
> what cpfind creates, and doesn't include the tuning I did for the
> "final" panorama.

No sign of a .pto, but probably not needed.

>
> So, my question: how do I lighten the cliffs on the right? Does hugin
> provide something to do that? Is there a way to trick it into doing
> so?

I'll have a snoop, and let you know how I get on.

Cheers,
--
Regards,
Terry Duell

Terry Duell

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Mar 19, 2014, 8:31:21 PM3/19/14
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Hello Greg,

On Thu, 20 Mar 2014 10:02:09 +1100, Greg 'groggy' Lehey
<groo...@gmail.com> wrote:



>
> So, my question: how do I lighten the cliffs on the right? Does hugin
> provide something to do that? Is there a way to trick it into doing so?
>

I have had some success.
I am running hugin-2014.1.0 (build of the current source) but any recent
version should be able to do the same.
In the stitcher tab, in "Panorama Outputs:" I selected "exposure
corrected, low dynamic range" (the normal output), and also "Exposure
fused from any arrangement".
The stitch from the latter shows quite an improvement.
The result using the original images may be a bit different, but I would
expect it will still be an improvement.
This approach is discussed in Bruno's tutorial at
<http://hugin.sourceforge.net/tutorials/auto-exposure/en.shtml>.

Let us know how you get on.

Dave H

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Mar 19, 2014, 10:49:04 PM3/19/14
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I just took the darkest image, brightened it in gimp and fixed the contrast a little.

I did not click the align button which skips the photometric optimization.

On the stitcher tab I checked exposure corrected, low dynamic range


Here's a link to my version of the panorama.

http://ge.tt/3mRDq4S1/v/0?c

Dave

Terry Duell

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Mar 20, 2014, 6:55:31 PM3/20/14
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On Thu, 20 Mar 2014 13:49:04 +1100, Dave H <panora...@gmail.com> wrote:

> I just took the darkest image, brightened it in gimp and fixed the
> contrast
> a little.
>
> I did not click the align button which skips the photometric
> optimization.
>
> On the stitcher tab I checked exposure corrected, low dynamic range
>
>
> Here's a link to my version of the panorama.
>
> http://ge.tt/3mRDq4S1/v/0?c
>

Hard to be sure about the differences, but it does look like Hugin gets
pretty close to that result using the "exposure fused" option.
00 - 08-3_blended_fused-small.jpg

Jan Martin

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Mar 20, 2014, 7:01:48 PM3/20/14
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How to do "exposure fused" by command-line only?
Without hugin?

Terry Duell

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Mar 20, 2014, 8:06:45 PM3/20/14
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Hello Jan,
Don't know, I have never tried that.
Have a look at the enfuse options, "enfuse -h" which may help.
Also, have a look at the Make file, attached. It was used to stitch Greg's
9 images with the "exposure fused" option.
It may give you some clues.
01 - 08.pto.mk

Greg 'groggy' Lehey

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Mar 21, 2014, 1:30:02 AM3/21/14
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Thanks. I've been in this in some detail, and rather than repeat what
I've written in my diary, I'll point to it:
http://www.lemis.com/grog/diary-mar2014.php#D-20140321-003415 (this
time hopefully with the right number of w's). In summary: yes, this
gives a more uniform lighting, but it "fused from any arrangement"
requires very accurate registration, and I didn't have that here.
Note also that you don't to select LDR as well; that just gives a
second panorama like the one I started with.

On Wednesday, 19 March 2014 at 19:49:04 -0700, Dave H wrote:
> I just took the darkest image, brightened it in gimp and fixed the contrast
> a little.

Thanks. I tried this too, a lot, and things worked better. Also
described in my diary.

Terry Duell

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Mar 21, 2014, 6:10:02 PM3/21/14
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On Fri, 21 Mar 2014 16:30:02 +1100, Greg 'groggy' Lehey
<groo...@gmail.com> wrote:


> Thanks. I've been in this in some detail, and rather than repeat what
> I've written in my diary, I'll point to it:
> http://www.lemis.com/grog/diary-mar2014.php#D-20140321-003415 (this
> time hopefully with the right number of w's). In summary: yes, this
> gives a more uniform lighting, but it "fused from any arrangement"
> requires very accurate registration, and I didn't have that here.

Curious, I got quite good registration with your downsized images.

> Note also that you don't to select LDR as well; that just gives a
> second panorama like the one I started with.

Sure, just explaining what I did, and which result was OK.

Greg 'groggy' Lehey

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Mar 21, 2014, 6:32:16 PM3/21/14
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On Friday, 21 March 2014 at 0:01:48 +0100, Jan Martin wrote:
> How to do "exposure fused" by command-line only?
> Without hugin?

You'll need a Makefile, and the best way to get one is from hugin.
That's what Terry attached. If you have a panorama called, say, foo,
then saving the project will save the project file foo.pto and a (GNU)
Makefile called foo.pto.mk. Take a deep breath and look inside:

# the output panorama
LDR_REMAPPED_PREFIX=foo
LDR_REMAPPED_PREFIX_SHELL=foo
HDR_STACK_REMAPPED_PREFIX=foo_hdr_
HDR_STACK_REMAPPED_PREFIX_SHELL=foo_hdr_
LDR_EXPOSURE_REMAPPED_PREFIX=foo_exposure_layers_
LDR_EXPOSURE_REMAPPED_PREFIX_SHELL=foo_exposure_layers_
PROJECT_FILE=/home/grog/Photos/Hugin-build-eureka/foo.pto
PROJECT_FILE_SHELL=/home/grog/Photos/Hugin-build-eureka/foo.pto
LDR_BLENDED=foo.tif
LDR_BLENDED_SHELL=foo.tif
LDR_STACKED_BLENDED=foo_fused.tif
LDR_STACKED_BLENDED_SHELL=foo_fused.tif
LDR_EXPOSURE_LAYERS_FUSED=foo_blended_fused.tif
LDR_EXPOSURE_LAYERS_FUSED_SHELL=foo_blended_fused.tif
HDR_BLENDED=foo_hdr.exr
HDR_BLENDED_SHELL=foo_hdr.exr

These are variable assignments, and you should be able to tie them up
with the choices in hugin's stitcher tab. You want
LDR_EXPOSURE_LAYERS_FUSED, so you say:

make foo_blended_fused.tif

If you're using BSD, you use gmake (GNU make). I'm not sure about
Apple; it could apply there too.

Greg 'groggy' Lehey

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Mar 21, 2014, 6:35:44 PM3/21/14
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On Saturday, 22 March 2014 at 9:10:02 +1100, Terry Duell wrote:
> On Fri, 21 Mar 2014 16:30:02 +1100, Greg 'groggy' Lehey
> <groo...@gmail.com> wrote:
>
>
>> Thanks. I've been in this in some detail, and rather than repeat what
>> I've written in my diary, I'll point to it:
>> http://www.lemis.com/grog/diary-mar2014.php#D-20140321-003415 (this
>> time hopefully with the right number of w's). In summary: yes, this
>> gives a more uniform lighting, but it "fused from any arrangement"
>> requires very accurate registration, and I didn't have that here.
>
> Curious, I got quite good registration with your downsized images.

Are you sure? That's my fault (hand-held), nothing to do with hugin,
but you need to look carefully. Compare
http://www.lemis.com/grog/Photos/20140317/small/Apostles-panorama-2b-detail.jpeg
and
http://www.lemis.com/grog/Photos/20140317/small/Apostles-panorama-2-detail.jpeg
which are at the bottom of the pano and to the right of the big rock.

Terry Duell

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Mar 21, 2014, 7:05:59 PM3/21/14
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On Sat, 22 Mar 2014 09:35:44 +1100, Greg 'groggy' Lehey
<groo...@gmail.com> wrote:

> On Saturday, 22 March 2014 at 9:10:02 +1100, Terry Duell wrote:

[snip]

>>
>> Curious, I got quite good registration with your downsized images.
>
> Are you sure? That's my fault (hand-held), nothing to do with hugin,
> but you need to look carefully. Compare
> http://www.lemis.com/grog/Photos/20140317/small/Apostles-panorama-2b-detail.jpeg
> and
> http://www.lemis.com/grog/Photos/20140317/small/Apostles-panorama-2-detail.jpeg
> which are at the bottom of the pano and to the right of the big rock.
>

OK. Sorry, I assumed you meant the optimisation error.

David W. Jones

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Mar 22, 2014, 1:41:52 AM3/22/14
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In similar situations, I've had good results by having Hugin output
48-bit TIFF or another high-dynamic range format and using Luminance HDR
to produce the final image.
--
David W. Jones
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wandering the landscape of god
http://dancingtreefrog.com
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