Curvemeister Forum

But I now have, I believe, refined this method slightly, by using Soft Light instead of Linear Light as the blend mode -- that gives much more subtle control.

Well, when you say “more subtle control,” what you mean is that the target layer has less impact on the source layer, so you can move the curves more significantly before going far outside the realm of real colors.  Making the control “more subtle” is indeed a good idea, hence the “zoom” layers in my action, posted above.

Soft Light, however, is not the right tool for this, in my opinion.  Using Soft Light makes it impossible to lighten blacks or darken whites, and makes the effect of moving the curve by some amount unpredictable.

To see why requires understanding how the various blend modes operate.  Here’s a good page for that, with explanatory pictures: http://dunnbypaul.net/blends/

Hi Jacob,

I stupidly thought that I had to adjust the L channel of the L layer, the b channel of the B layer etc of your action - question of not thinking before jumping in! - sorry.

I wonder if PS scripting would help, by allowing one to pick the seed mask (from any colour space?) rather than have the 3 lab channels.  One then would have a lovely tool for 2nd passes etc, building on what one has already done.

I've got a terrible image - flowers in church under sodium lighting - which I must see if I can improve compared to any other technique (none of which have been particularly good)

Well I've had a 10 minute bash having to use all the Ladder layers and the result beats my previous attempts in rgb & lab
Here is before/after

I wonder if PS scripting would help, by allowing one to pick the seed mask (from any colour space?) rather than have the 3 lab channels.

Actually, now that I consider it, when the action does the apply image step, it should just use the current composite view to pick its L*, a*, and b* channels from, instead of only pulling them from the selected layer.

Also, I already use another action which makes a “Jacob’s Ladder” adjustment group based on a single channel, and pops up the apply image dialog to let the user pick which channel to use (what you’re calling the “seed mask”, and I call the “adjustment source”—working out a complete set of well defined terminology for all the parts of this would be good).  Maybe I’ll add it to the set of actions I uploaded.

As far as I can determine it is almost impossible to correct for sodium lighting as it.

According to my research on the web - Sodium light is monochromic yellow light (color temperature is around 2100 degrees) and as such, there is no "color balance" possible.

So any correction is very hard.  I plan to do some tests with coloured cards, ond day, to see if I can come up with something better.  Trouble is people want me to photograph the flowers in church on a regular basis and I've failed to find a good solution - flash tends to make things worse because I thenhave mixed light sources!

Well I've had a 10 minute bash having to use all the Ladder layers and the result beats my previous attempts in rgb & lab

Wow, what a rough image.  The flowers are super tricky, as they seem to be lit by two different-temperature light sources.  Here’s my try.

Well, when you say “more subtle control,” what you mean is that the target layer has less impact on the source layer, so you can move the curves more significantly before going far outside the realm of real colors.  Making the control “more subtle” is indeed a good idea, hence the “zoom” layers in my action, posted above.

Yes, all true. I just find the zoom layer approach to be . . . one layer too many for my refined taste. :-)

Soft Light, however, is not the right tool for this, in my opinion.  Using Soft Light makes it impossible to lighten blacks or darken whites, and makes the effect of moving the curve by some amount unpredictable.

Yes, all true, too. Except . . . there are many scenarios where I do not want to lighten/darken the endpoints, but want to leave them totally unharmed, and for that the Soft Light mode is just gorgeous: I can make radical changes to almost all values in my image and yet remain assured that the most subtle highlights and shadows stay amazingly well in their proper place. And hey, this is not a life-changing permanent marriage: we can use whichever blend mode suits our current editing needs. Options are good!

* Convert the image to CIELAB (obviously)

* Copy the L* channel (I

* Create a new layer, and paste the L* channel into all three
channels (L*, a*, and b*).

* Set the blend mode of this new layer to "Linear Light,"[†]
and bear with me here, because at this point the image will
look like a black/white posterized splotch. I usually name
this layer something like "L*-based corrections".

* Add a new curves adjustment layer, and set it as a clipping
mask.

* Make all three curves--L*, a*, and b*--completely flat, i.e.
Input 0 -> Output 50, In 100 -> Out 50 in the L* channel,
and In -128 -> Out 0, In 127 -> Out 0 in a* and b*. At this
point you should have an image that looks exactly like the
original, because Linear Light blend mode makes no change to
the bottom layer where the blend layer is middle gray.


Hi everbody

I am new to CM and "Jacob's Ladder" looks interesting. I have a question, how does it work in PSE?

Thanks
Andrew

It probably will not work in PSE because of the poor support for Layers and such...

Greg

It probably will not work in PSE because of the poor support for Layers and such...

Greg

Hi Greg

Thank you, I will have to learn other tricks in that case.

Cheers
Andrew