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Author Topic: How to white balance a series of images to get similar colors ?  (Read 2847 times)

manfred1

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How to white balance a series of images to get similar colors ?
« on: November 25, 2013, 05:13:03 pm »

Hi,

for an architectural work, I would like to keep colors similar for a series of photos.

Now I started to use a white balance card (actually the white balance target of a XRite ColorChecker Passport).

I have taken a series of photos of an altar (built of red freestone/sandstone) in a church (using the same camera and the same lens) . During the shooting the natural light (sun through windows) changed a little bit (I guess 1 to 1.5 EV).

I took a first series of photos. During this time the sun did not change much. Then I took a shot of the white balance target. The white balance shot was about  0.3 to 0.5 EV different from the image series.

Then I shot a second series of images. The sun was now a bit darker but changed not much during this series. At the end I I took another shot of the white balance target.  Again the second white balance shot was about  0.3 to 0.5 EV different from the second image series.

At home in Lightroom,  I white balanced the first series of images using the first target shot and the Synchronize Settings dialog. And  did the same for the second series and the second target shot.

My assumption was that at the end  the colors of the altar should be more or less the same. But ... one serie of images is much warmer than the other and maybe a little bit more red.

Is there something I missed? Why are the colors of the image series not the same?

Thanks for your help.

Manfred
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Bart_van_der_Wolf

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Re: How to white balance a series of images to get similar colors ?
« Reply #1 on: November 26, 2013, 05:18:07 am »

Is there something I missed? Why are the colors of the image series not the same?

Hi Manfred,

Hard to say, but could it be that the white balance card was shot at a different angle, which could semi-specularly reflect more or less of one of the lightsources in a mixed lighting situation?

Cheers,
Bart
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== If you do what you did, you'll get what you got. ==

D Fosse

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Re: How to white balance a series of images to get similar colors ?
« Reply #2 on: November 26, 2013, 06:05:45 am »

Yes, I think this is a timely reminder to be very careful when placing the colorchecker, making sure it doesn't face strongly colored surfaces. Especially if they are directly lit, for instance by sunlight through windows. That must be the explanation.

Always wear a black suit... ;D

EDIT: I actually typed Windows with a capital W there...maybe I should just let it stand... :D
« Last Edit: November 26, 2013, 06:12:24 am by D Fosse »
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manfred1

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Re: How to white balance a series of images to get similar colors ?
« Reply #3 on: November 26, 2013, 05:33:00 pm »

Hi,

thanks for the hints.

>...but could it be that the white balance card was shot at a different angle...

I think this was not the case.

What I have seen with other target shots: the white balance target was the brightest area in the image (darker red sandstone). In LR I have seen Lab luminance values of 95-99 for the targets. And using very high values LR is no longer able to white balance the images.

So an additional question would be: is it recommended to use the same ISO/aperture/speed for the target shots as for the regular shots? Even if the target has Lab luminance values of >90 or > 95? Or should I use e.g. -1 EV for the target shot?

Thanks.

Manfred
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Bart_van_der_Wolf

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Re: How to white balance a series of images to get similar colors ?
« Reply #4 on: November 27, 2013, 06:46:02 am »

What I have seen with other target shots: the white balance target was the brightest area in the image (darker red sandstone). In LR I have seen Lab luminance values of 95-99 for the targets. And using very high values LR is no longer able to white balance the images.

So an additional question would be: is it recommended to use the same ISO/aperture/speed for the target shots as for the regular shots? Even if the target has Lab luminance values of >90 or > 95? Or should I use e.g. -1 EV for the target shot?

Hi,

Overexposure of a white balance target will lead to inaccurate results. Try and keep White reflection patches at an exposure level that translates to a Raw conversion of about R/G/B [235/235/235] at default settings.

Cheers,
Bart
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John Nollendorfs

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Re: How to white balance a series of images to get similar colors ?
« Reply #5 on: November 27, 2013, 11:35:39 am »

DataColor's SpyderCube is what you should be using. It has black, white and neutral gray targets. Plus it has a black trap and a chrome ball for spectral highlights.

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jjj

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Re: How to white balance a series of images to get similar colors ?
« Reply #6 on: November 27, 2013, 12:39:30 pm »

For fixing the problem after the fact, have you tried using Photoshop's match colour command?
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manfred1

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Re: How to white balance a series of images to get similar colors ?
« Reply #7 on: November 28, 2013, 02:28:30 pm »

Hi,

thanks again for the hints, especially the 235/235/235 values for the white balance target and the PS Match Color. Match color helped to make the colors of the two image series more similar.

Manfred


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