Topic: Wow - blows my mind

[themightyzog]

re the clocks Mike,

The trouble is they are screen based and so not that accurate, especially in the greens and not a patch on CM, but I find them useful sometimes, particularly when I cant use CM - as in this technique.

I rather like this mode for fun Lab corrections where the circles show the lab values!

[KlausNordby]

Wow indeed. Yes, a radical approach -- I must admit it sounded senseless at first, when I just read it. 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.

[jacobolus]

Okay, an action.

And some screenshots in sequence:

[themightyzog]

Interesting and different from your initial posting (assuming I read it correctly).

I do not like the Lab channels being shown back to front in our action!  b-a-l
and also it would be a heap better to just have one adjustment curve layer, rather than having to switch between them, which is extremely slow.

But for me the beauty of your simple first approach has gone - adjusting curving using the same seed mask.  This is extremely intuitive as any point on the image is at exactly the same point on all 3 curves - not as powerful as your action, but great for relatively simple adjustments.

Am I also correct in thinking that by effectively doing an auto-levels on the channels, there are now big gaps in the histogram?  I had thought of doing this and came to the conclusion that a bit of blurring would be in order to smooth things out again.  Perhaps I am missing something here.

There certainly is lots of room to experiment with your initial idea - but for simple people, like me, I need to pre-visualise what will happen when I curve - your action does not give me this.

[jacobolus]

Interesting and different from your initial posting (assuming I read it correctly).

No, it's identical.

Am I also correct in thinking that by effectively doing an auto-levels on the channels, there are now big gaps in the histogram?  I had thought of doing this and came to the conclusion that a bit of blurring would be in order to smooth things out again.  Perhaps I am missing something here.

All this does is zooms the horizontal axis of the editing curve, clipping it to the region where moving the curve will have any effect.  Because this layer is only used for adjustment, beginning by default with no effect, it doesn't really matter very much that there are gaps in the histogram.  I always use 16 bit/channel mode to avoid rounding errors here, but I'm not sure it makes too much difference.

There certainly is lots of room to experiment with your initial idea - but for simple people, like me, I need to pre-visualise what will happen when I curve - your action does not give me this.

Why can't you previsualize?  If you click around in the image while the curve is up, you can see which parts of the image correspond to which part of the curve, and then by knowing what the image looks like, what its numbers are, etc., you can decide what you want to do with each part of it.

I think one thing which might make an improvement here would be to figure out a way to add three (step?) gradients at the bottom of the image to make it easier to see precisely what's being done to specific colors.

This is extremely intuitive as any point on the image is at exactly the same point on all 3 curves - not as powerful as your action, but great for relatively simple adjustments.

This is still the case.  If you want, just chop the a* and b* layers out of the action, or delete them once it is complete.

and also it would be a heap better to just have one adjustment curve layer, rather than having to switch between them, which is extremely slow.

If one adjustment curve layer could fit 9 curves on it, I'd totally jump on that.

I do not like the Lab channels being shown back to front in our action!  b-a-l

Okay, I've uploaded a revised action, with the order reversed.

Also, an identical action with explanatory stops inserted.

[jacobolus]

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/

[themightyzog]

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)

[themightyzog]

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

[jacobolus]

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.

[themightyzog]

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!

[jacobolus]

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.

[KlausNordby]

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!

[curvey]

* 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.
[/quote]

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

[Greg Groess]

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

Greg

[curvey]

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