Taking the bart to MacWorld Revisited....

[ggroess]

It was a bright sunny day today, on the way in to MacWorld, and I was thinking about neutrals as the brightly lit buildings of city of Oakland flashed by.  Although I know that the sky is blue, and that shadows are lit by the sky, for the life of me I could not see a hint of blue tint in any of the shadows. 

Every single shadow was perfect gray, without a hint of blue.  It occurred to me that this is one way of looking at the function of a neutral in an image: we want to duplicate the effect that we see when we are there looking at the scene.  We should not, normally, allow the the shadows to appear blue in our photographs.

Another way to look at this is that we should try to recreate the color of the object in the image, and disregard the color of the light falling on the object.  There are images where we want to convey a certain mood, or where the light itself is part of the subject (sunsets, for example), but the bedrock of color correcting an image is to compensate for the effects of colored lighting, camera processing, windows, or any other thing that may add a color cast ot the image.

I'd be interested in others' take on this - the concept of a neutral, and of removing a color cast, is so important that I think it's worth looking at different ways to describe it.

Ok..Slowly taking my foot out of my mouth and taking another swing at this....

Mike, et.al.
Today while slogging away on the treatmill during my workout and watching some scenic video used for relaxation...I saw the effect you were trying to describe.  What struck me about this at that moment was that the amount of blues in the shadows was a function of distance from the lens.

Items close to the viewer or better described as "not too distant" did indeed have a neutral or nearly neutral shadow.  It was a scene of trees with fresh fallen snow, with a mountain stream running nicely down the middle, and the mountains in the distance. 

Here is what I "saw" items in what we might call the foreground (first 2/5 ths of the focal range) were sharp and had very little color shift in the shadows.  Items in the middle 2/5ths had a moderate shift to the blue range and this was dependent on the lighting angle....items in the last 1/5th (farthest from the lens) had a distinct shift to the blue/cyan side of the street.

So what does this mean for us as Curvemeister Cadets.....

Adjustments for "blue" shadow cast in the far background are going to over correct for the middle ground.  Over correct for the shift and you cause trouble elsewhere.  Grand Canyon pictures are really good examples of this...

I'm not sure if there is a "formula" answer for this.  It could be Masking and a lot of blending...It could be a graduated mask...It could be an correct the foreground and middle and allow the rest to go since the color really is there in the scene and not added by the camera....

A side thought that came to me Mike was a "Digital Polarizing Filter"  we have been playing all week with the haze images and have been able to curve our way out of a lot of the haze.  Could there be or is there a stock curve that we could load to do the heavy lifting so to speak and get us in the ball park without all the muss and fuss of initial guessing....

Thanks for your time and comments...
Greg

[mikemeister_admin]

I think if you look at painting, particular old masters, that this is the method they use.
I'll ask my daughter in the morning and she may be able to add to this dicussion

[mikemeister_admin]

This is what my daughter said...

My background is art, specifically painting/designing scenery for theatre and film.  One thing I learned early on is that the further objects are away from you, the bluer they become.  This is really important when painting scenery, because it's this primarily, coupled with hazy/lower contrast, that gives the eye spatial relationships.  You can observe this just by going outside and looking at a landscape, and by looking through any of the paintings by the old masters. 


The eye is drawn to contrast - where you put your whitest whites and darkest darks next to each other is where the eye will go first - in a landscape you tend to want this to be the foreground.  Here you invest in the detail, and colours are as true as you want to make them.  As you move into the distance colours become bluer, but also you don't draw everything perfectly, but leave more and more to the imagination by just focusing on general shapes without hard edges.
...

Helpful?

[-default]

I don't really disagree with anything that's being said here.  What I would add is that producing an image with no color cast, even in distant objects is an important fundamental task that we'll be approaching from several different angles, finishing up with masks in the last week or two. 

The fact that artists and others add the blue to their distant landscapes is not the result of default behavior of their paints, but of careful training and thoughtful application of that training.  I believe it should be the same with our photographs.  Rather than trust the rather exaggerated blues that our cameras hand us, we should be able to control just how much blue is there, and allow only the amount (for the time being the goal is zero) that adds to the impact of the image.