Mixed Lighting ... WB Challenge
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RustyBug
Registered: Feb 02, 2009
Total Posts: 12948
Country: United States

Coming on the heel's of wrestling with Jim's Wyoming Rockies, this is from the same day as the Skyward image I posted.

Anyone that's been watching for a while knows that I really have this thing about "blue snow", "blue hair" etc. (OCD to some, I'm sure)

Anyway, I was shooting this as part of a test shot (series) to help illustrate some physics theories with someone who wasn't quite grasping my written explanations (different topic) ... go figure.

Anyway, as part of that endeavor, I recognized the opportunity to capture / illustrate the mixed lighting that occurs in nature that I'm always espousing about ... as the colors are reflective of the light that is naturally occurring.

The fence is entirely the same color (i.e. white) and as is easy to see, it is simply reflecting the light that is illuminating it, iaw with AI=AR (uh-oh physics geek warning ), The salient point here is to show that our subject is receiving light from "two" different sources. One being the direct (specular) warm sunlight, the other being the indirect (diffuse) cool skylight.

On many occasions, the sources are more "blended" together to create a homogenous source. And to a degree, the color of the direct light typically overpowers the color of the indirect light. But as our angles move around from 0 - 90 (and nearly 180 here) we encounter a greater degree of separation between them. As is the case with "golden hour" stuff, the luminance levels of the direct light is reduced, yet the indirect light remains essentially constant ... but relative to the other times of day, it now appears stronger as byproduct of less direct lighting influence.


So, here's the $64,000 question ...

How do you adjust WB to make the white fence ... white?



I'd like to hear & see what everyone's approach / opinion is regarding this. To borrow from Karen ... "Have fun"


ben egbert
Registered: Jan 31, 2005
Total Posts: 6531
Country: United States

Well my first question is why would I want the fence white? It is painted with white paint, a very reflective color. It will and should act as a good reflector of the colors it is reflecting. It probably will be white when the sun is overhead but when the light is yellow/orange/red and yes the blue of shadows, it will reflect the color presented.

But in the nature of a lesson, I believe you want to find out how to make it behave as if it were being illuminated with neutral light. In that case, I think you have to apply color corrections to each area. One to the yellow area, another to the blue area etc.



Camperjim
Registered: Oct 17, 2011
Total Posts: 1895
Country: United States

I agree with Ben. The fence should not appear white if it is being illuminated by warm sunlight. If you do a color cast correction to move the fence to white, then the posts will turn dark, neon blue. If you also want the posts to be a neutral gray, then you will end up with a monotone image.



ben egbert
Registered: Jan 31, 2005
Total Posts: 6531
Country: United States

Hi Jim, I prefer the original and think it pretty well matches reality. But I am impressed with the correction you made.

Color correction is probably the most difficult post processing thing for me for at least two reasons. I don't know my opposites, and I don't have good enough color vision to know when I have it right. I would see white where others see a green or blue cast.

I still don't see the green cast you mentioned in the Wyoming image redo I presented. But I am sure you are correct and it is outside my threshold.



AuntiPode
Registered: Aug 05, 2008
Total Posts: 6778
Country: New Zealand

If you just want the warm toned fence face rendered as white/gray, without a color cast, but want to retain the blue color cast of the fence parts in shadow, one way is to use the color select to pick the warm fence areas and clean up the selection with the option (alt) lasso tool to subtract the odd areas that the color selection also catches. Then, rather than trying to color correct, use the selection to apply a hue/sat layer to remove all the color from the selection and adjust the lightness to make it look white/gray the way you choose. (Selection shown before cleaning it with [mac] alt-lasso tool.)



sbeme
Registered: Dec 23, 2003
Total Posts: 17381
Country: United States

Good strategy, Karen.
The whole thread is useful to me as a teaching exercise.
I know its not the point, but the original version is by far the most appealing. The warm vs cool front to back and alternating tones IS what makes this image worth looking at more than once or twice.

Scott



lylejk
Registered: Jun 12, 2004
Total Posts: 3809
Country: United States

To be honest, I liked the original as is. Still, thought I would take up this challenge. I used an iterative convoluted flow (involved color picker then created a fill layer with that color set to subject, merge down and set that result to saturation and desaturated that layer and set the original layer on top set to color; pretty convoluted, but it did it for the both the orange and blue colorcaste and it did retain the background colors) for this result.







RustyBug
Registered: Feb 02, 2009
Total Posts: 12948
Country: United States

Thanks guys ... interesting to see the replies.

Also, interesting to see how much desaturation is being used. I realize that the fence is white and for that, the desat works pretty well. But, if we insert a person in place of the fence (or fenceposts) as the subject and don't want monochrome ... then what ?? I know I asked how to make the fence white, but I guess I meant how to render it neutral when being lit by two different colors.

I may see if I can find a colored (i.e. non-white) subject to play with under similar lighting scenario.



AuntiPode
Registered: Aug 05, 2008
Total Posts: 6778
Country: New Zealand

You could make two versions with different color temperature settings in ACR and mask them together in PS.

Alternately, use a mask and color balance adjustment layer - simpler but getting the adjustment right may be fiddly.