white balance in panotools

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white balance in panotools

PanoTools NG mailing list
Hi allI am looking at the panotools code and do not understand the workflow to correct white balance. I know hugin does all this correction but I am more interested on the concept and the code behind it. I hope someone can help

What is done first white balance or exposure compensation ?If one image is used as ancore for white balance then the others are corrected based on the ancore so the overlaping areas in the panorama are not taken into account?Is ok to apply white balance at the final panorama or it should be done only to the inputs?
Shoud it be calculated based on all the image or only in the overlap?

Thanks a lot
 Enrique
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RE: white balance in panotools

PanoTools NG mailing list
Best case, WB should be corrected during the raw conversion and never corrected afterwards.

Any adjustment in WB on one image should be the exactly same across all images.

Ideally, a physical reference card should be shot to calibrate colors, to ensure you have correct scene colors.

Effectively, a good monitor and eye is more than enough, unless it’s for people that require exact color details for paint, tiles, artwork etc.

Even then such subjects can sometimes have a significant different color response between natural and artificial light.

 

Best Regards,

 

Sacha Griffin

Southern Digital Solutions LLC  - Atlanta, Georgia

http://www.seeit360.com <http://www.seeit360.com/>

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IM: [hidden email]

Office: 404-551-4275

 

 

From: [hidden email] [mailto:[hidden email]]
Sent: Friday, May 13, 2016 10:04 PM
To: yahoogroups
Subject: [PanoToolsNG] white balance in panotools

 

 

Hi all

I am looking at the panotools code and do not understand the workflow to correct white balance. I know hugin does all this correction but I am more interested on the concept and the code behind it. I hope someone can help







What is done first white balance or exposure compensation ?

If one image is used as ancore for white balance then the others are corrected based on the ancore so the overlaping areas in the panorama are not taken into account?

Is ok to apply white balance at the final panorama or it should be done only to the inputs?



Shoud it be calculated based on all the image or only in the overlap?







Thanks a lot



 

Enrique



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Re: white balance in panotools

PanoTools NG mailing list
In reply to this post by PanoTools NG mailing list
Hi Enrique,  

 I agree with Sacha. Do all your WB correction before you stitch. My workflow is now to shoot in raw and then convert to tiff. I always shoot a WB card in the very last shot, usually the sideways one to cover the nadir tripod hole, I can put the card on the ground or hold it in my hand as it won't be seen in the final stitch.
 

 When I'm processing the set of raw images I know the last shot in any sequence is the one with the card in view, so I count backwards to make sure I've got a full set of images, eliminating any false starts, etc.
 

 I correct the WB in that image and apply it to the rest of the raw images, including any other tweaks I want to apply such as sharpening, chromatic aberration, etc. I'm using the camera's own raw converter as this seems to know more about the lens characteristics, etc and outputs good images for me.
 

 Regards,
 

 Keith
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Re: white balance in panotools

PanoTools NG mailing list
In reply to this post by PanoTools NG mailing list
Best to have matching color and exposure while shooting by locking both white
balance and expose of all cameras.

But if needing to match color of images from multiple cameras that do not have
the same settings. Probably they can only record in auto. Then:
- Only look at the overlap area between images.
- Only evaluate the values that are not near being clipped.
- Only evaluate the values that are close in value. disregard where a is really
great to not be influenced by moving subject.

Instead of "Only" it might be better to be "Mostly" so all pixels are not
eliminated.

I remember using the old PanoTools tool for color balance when shooting panos on
auto, and not having the images exactly aligned caused color changes that were
not accurate. Hugin, PTGui, and VideoStitch do a better job, but I don't know
what is different.

Question might be better answered on the Hugin-ptX list.

On 2016-05-13 11:03 PM, Enrique Molano [hidden email] [PanoToolsNG] wrote:

>
>
> Hi all
> I am looking at the panotools code and do not understand the workflow to
> correct white balance. I know hugin does all this correction but I am more
> interested on the concept and the code behind it. I hope someone can help
>
> What is done first white balance or exposure compensation ?
> If one image is used as ancore for white balance then the others are corrected
> based on the ancore so the overlaping areas in the panorama are not taken into
> account?
> Is ok to apply white balance at the final panorama or it should be done only
> to the inputs?
> Shoud it be calculated based on all the image or only in the overlap?
>
> Thanks a lot
> Enrique
>


--
Jim Watters
http://photocreations.ca

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