Mixed lighting

Jacob Rus's new curve-based technique, with examples
ggroess
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Postby ggroess » Wed Sep 10, 2008 11:21 pm

Zog,

I appreciate the humor and grace...

Mike and I scour the archives looking for the best of the worst images for the class...If they were easy...well where's the fun in that.

For my take on the image you stated that: "Here is a a mixed lighting shot - the stone is not painted it is all the same colour"

I took the blue light to be the natural light of the scene and worked to make the yellow sodium light disappear. 

I prefer natural light when it is there  (Personal Bias) To me the yellow was the problem to be solved not necessarily the color to be matched.
During my analysis of the image I saw two really big problems...
1) Yellow lights in the arches
2) The stained glass.

Secondary issues were the correct colors for the darker parts of the ceiling, control of the shadows near the alter and color saturation since I knew from the get go I was killing colors off in the image....not having been there I felt I had a bit of room there.  Now that I look at the other images provided I see that I went too far in that regard...

The limits in CM were mostly curve guard issues that I over came with a mask.  Since I did not need to adjust for any other color except the yellow I was free to lock down the blue side of the B channel and crank it up to see what I could do.  I ended up making the B curve flat on the central axis to the center and then using a "Contrast Pin" to link two points on the curve I lifted the entire B curve upwards so that the bluish cast in other areas was reduced. Control points were removed as I went to keep the blue side of the B channel in line.

I would say to you and any others that if great images are the goal nothing you can do is cheating.  No one is going to have a penalty for success....

For the purpose of the class we want to learn how to use CM.  To that end I would say you "cheated" but... I think Jacob's Ladder is a interesting curves technique that Mike is going to have to wrestle with going forward.  I am still trying to get my brain wrapped around it.  for those still trying to understand the jacob's ladder technique you can read about it in http://www.curvemeister.com/forum/index.php?topic=2078.0

Just as I would caution anyone getting too locked into a single color space I would say that JL has a time and place.  Just as LAB might be a better space than RGB in some situations or HSB has advantage over CMYK.

Everyone remember that this week is a time to push some limits and see what this plug in can do...Again don't get scared off...There is much to learn but loads of help.....

Greg

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Postby j2e4a8n » Thu Sep 11, 2008 3:52 pm


I prefer natural light when it is there  (Personal Bias) To me the yellow was the problem to be solved not necessarily the color to be matched.
During my analysis of the image I saw two really big problems...
1) Yellow lights in the arches


I applaud at this.  clap  ;D clap

mikemeister_admin
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Postby mikemeister_admin » Fri Sep 12, 2008 2:57 pm


I think Jacob's Ladder is a interesting curves technique that Mike is going to have to wrestle with going forward.  I am still trying to get my brain wrapped around it.  for those still trying to understand the jacob's ladder technique you can read about it in http://www.curvemeister.com/forum/index.php?topic=2078.0

Just as I would caution anyone getting too locked into a single color space I would say that JL has a time and place.

I’ll be putting up a fuller description on my site at some point with a tutorial which explains via handling several tricky example images (& showing the curves that fix them, &c.), first trying to explain what exactly adjusting the “adjuster” curves does after running my action & how they can be used to color correct images, & only later (for those interested in the nitty gritty) explaining how the linear light blend mode, a couple apply image steps, & some curves actually coöperate to achieve the effect.  School is just starting again though, and I need to pick courses & then start writing papers, go to various student publications’ meetings, help register voters for the upcoming election, &c., so I’m not completely sure when I’ll have that finished.

-Jacob

Edit: here are the currently online images that I have used this technique on.  My laptop’s file system got a bit fried, so earlier efforts won’t be put online until sometime in the future.

http://www.hcs.harvard.edu/~jrus/colortheory/jl.html

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Postby mikemeister_admin » Fri Sep 12, 2008 7:59 pm

Jacob, great examples on your Harvard (!) site, I'm looking forward to reading and seeing your nitty-gritty explanations!  And it seems that the "Jacob’s Ladder" name, which "someone at Colortheory" came up with, is beginning to stick. ;-)

ggroess
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Postby ggroess » Fri Sep 12, 2008 9:09 pm

Jacob,

Don't get me wrong...I am certainly going to explore the technique and see what I can gain from it. 

I think it is very creative and innovative. 

I worry about the new people getting into the class and having a tough enough time getting the CM stuff.  I just wanted to make sure that we do not scare anyone out of taking the CM class because they are getting too much here in the free form part of the class...I know this is an open area and I want to challenge people to be better but I don't want to start them off with the very deep end of the pool either....

I know it seems a contradiction but I really am trying to keep the new people in mind as I type this...In fact I am looking forward to  learning about Jacobs Ladder going forward.
Greg
Please accept my apologies if you took anything other than full support from my previous posting...

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Postby mikemeister_admin » Fri Sep 12, 2008 9:20 pm

I worry about the new people getting into the class and having a tough enough time getting the CM stuff.  I just wanted to make sure that we do not scare anyone out of taking the CM class


Sure, no problem. I’m certainly not trying to hijack your forum or confuse all the newbies. :)

Please accept my apologies if you took anything other than full support from my previous posting...


No, not at all.  My response was to the “need to wrestle” bit, and I was just saying I’d try to put up a better introductory explanation sometime to facilitate the wrestling. :)

To be honest, I’ve been glad for the interest here, as the Applied Color Theory mailing list seemed mostly to ignore the thread.

ggroess
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Postby ggroess » Sat Sep 13, 2008 2:10 am

indeed they want to print things and argue about color spaces....

My current take anyways...

Greg


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