Jacob's Ladder

chuckinsocal

I've been trying to figure out Jacob's Ladder to improve my images but I'm stumped on the very first page where he says "notice that we curve from a horizontal line!" :dunno .

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I don't know which version of PS he's using in his illustrations but I use CS3 and I don't see any way to create a horizontal base line. I can drag the ends of the lines to make the line horizontal but that totally wrecks the image. I've tried his actions but they don't seem to work either. [Edit: I've reread his actions page and now realize that there are several actions that need to be run so back to the books on that, but I'm still left with the horizontal base line issue.]

[Edit 2: OK ... in following his actions I find that the horizontal base line is created, I believe, when he creates a curves adjustment layer but I'm having trouble replicating that.

In creating a curves adjustment layer, I find the following steps in his action:

Curves: Point List
Point: 0,127
Point:255, 127

I think this is where the horizontal curves base line is created but I can't find this Point List. Anyone know where it is?

Thanks.

BinaryFx

You have missed a step, I would suggest that you carefully go over the original instructions. The horizontal curve can only work when the adjustment blending is in a blend mode where 50% neutral gray is treated as transparent/null (overlay or the "light" blending modes).

About a year before Jacob's Ladder was discovered by Jacob, another separate, earlier author made this tutorial which is similar in the key points to the later technique described by Jacob, here is the earlier unrelated post from stroker/warjournal:

http://tech-slop.serveit.org/wiki/index.php?title=Curves_and_Linear_Light


Hope this helps,


Stephen Marsh

http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/

chuckinsocal

Thanks Stephan ... it helps a lot! It removes the obstacle that is holding me back. But, I'm guessing others may arise.

The original instructions state how simple all this is to do, and I guess it is if one knows what one is doing, which I really don't. So I'm just trying to figure it all out one step at a time.

So, armed with your information I shall continue on with the challenge and if I get half way good at it I'll post some results.

Thanks again.

BinaryFx

chuckinsocal wrote:

Thanks Stephan ... it helps a lot! It removes the obstacle that is holding me back. But, I'm guessing others may arise.

The original instructions state how simple all this is to do, and I guess it is if one knows what one is doing, which I really don't. So I'm just trying to figure it all out one step at a time.

So, armed with your information I shall continue on with the challenge and if I get half way good at it I'll post some results.

Thanks again.

I think that you should probably contact Chris and point him to this page so that he can see the problem with his introduction to this technique! Chances are that others are having problems too, if they are following the same page, although the action should be correct (I presume).


Sincerely,

Stephen Marsh

http://members.ozemail.com.au/~binaryfx/
http://prepression.blogspot.com/

chuckinsocal

A little progress!!!

I was able to replicate the horizontal base line by using the overlay blending mode. After I make the base line in all three channels (L, a, b) horizontal my image looks just like it did before the adjustments which I think is the point. The only difference is in my input and output values in the curves dialog.

For my Lightness channel, the left end of the line has Input of 0 and an Output of 50. The right side of the line has Input of 100 and an Output of 50.

For my a and b channels, the left end of the line has an input value of -128 and an Output value of 0. The right end has an Input of 127 and Output of 0.

But the curves seem to function OK. After creating the horizontal base line in all three channels, I anchor it at the intersection of all the vertical grid lines using the smaller squares grid. Then using the eye dropper I identify where on the base line the color I want to change is then move the line at that point up or down as needed.

I'm at the very beginning of this experiment so what I'm doing is very primitive and probably needs some refinement but it does seem functional and gives me a foundation on which to build some of the other more advanced steps. If I get good at it I'll post some before and after shots.

Thanks so much again for your input. It's greatly appreciated.

jacobolus

You might try this action which sets up such curves for you:
http://www.hcs.harvard.edu/~jrus/colortheory/Jacob%27s-Ladder.atn

chuckinsocal

WOW ... thanks for that ! I just fiddled with it for a few minutes and it seems to make much more sense than the action I've been trying to decipher. I'll play with it more later when I have more time. I'll keep you posted.

Thanks so much again.