Topic: Mixed lighting

[themightyzog]

Here is a a mixed lighting shot - the stone is not painted it is all the same colour

What can you do with it?

[Jean Pierre]

I tried with the channel mixer... but I dont really understand it yet.

So I corrected the blue chanel in Lab and Rgb.
I tried to find a neutral without success.
I tried to make a pin from the right arch and then applied it to the blued stone; but this too I dont quite understand.

[ganna]

I zapped it with my friend sledge hammer (Lab mode)

[gremurphoto]

Shad,Highlight,Neut in RGB,color boost in Lab

[gremurphoto]

Played with the perspective control,drained a little yellow and pulled down brightness in HSB

[Jean Pierre]

Shad,Highlight,Neut in RGB,color boost in Lab

Where did you found your neutral point?

[gremurphoto]

Shad,Highlight,Neut in RGB,color boost in Lab

Where did you found your neutral point?
At about 10:00 on the left wall.It read about Red=196,Blue=196,Green 194,close enough for a neutral.SeeMSnap066

[Greg Groess]

Zog...You continue to amaze me....

I think I'm going to ship you some color correction filters and a good book on mixed lighting....

ok...This is my swing at your mixed lighting image.

Process as follows:
1) Open in PS copy the background as a new layer... use CM in LAB mode to set a neutral on the blue part of the stone.  I shopped around for the neutral until I hit a pretty good spot.  Then using the saturation slider I boosted the color a bit knowing I would need it later...Closed CM to apply the changes to the layer copy.

2) Copy the background copy layer to a new layer called mask..Open CM and use the mask carte to find a good mask for the yellow parts of the image...I used the B channel of LAB because it was quick.  Adjusted the mask to ge the most contrast and then slid the entire curve to the left on my setup to increase the contrast even more.  Copied the channel using the CM tools and pasted it into the layer called MASK in PS as a mask.  Alt-Click then paste.

3) re-opened the Mask layer in CM and adjusted the B channel until the yellow was really reduced in the archways Had to make a "linked" vertical move in CM to get rid of some of the tougher yellow parts. I Used a very wide soft brush to paint on the mask a bit to refine the adjustment. Closed CM and flattened the image.

4) re-opened in CM and using the saturation slider I adjusted until I deceided that there was just too many different ways to adjust this.  

Posted the result and vowed to find a way to hunt Zog down....(Kidding)

Greg

[Greg Groess]

Shad,Highlight,Neut in RGB,color boost in Lab

Where did you found your neutral point?

We will be covering neutral very early on in the class.  This is one of the toughest concepts to get across.  It is very subjective sometimes and in many cases there is no neutral in an image. 

Try this...

http://www.curvemeister.com/wiki/index.php?title=Neutral_Thresholding

Greg

[themightyzog]

Well Greg,

I am always in awe at the way you and Mike manage to take such awkward photos for us to play with, so I thought I join in!

Unlike you two, I find it very hard to take pictures that need so much attention, but I was lucky enough for the camera to go a bit wonky during a bracketing run.

Here is the previous shot in the sequence, that is more like the actual lighting and finally a very very quick adjustment using Jacobs ladder of the original blue one - yes a big cheat, but then that is one of the things you have taught me!  I did try using CM, but my results were pretty poor and it was a lot of hard work.

So lets have an easier one to try tomorrow.

[Greg Groess]

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

[Jean Pierre]

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  clap

[jacobolus]

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

[KlausNordby]

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. ;-)

[Greg Groess]

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...