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J
J Isner
Inspiring
February 4, 2017
Answered

Convert from Levels to Curves

  • February 4, 2017
  • 3 replies
  • 2202 views

Does Photoshop CC have a feature that lets you convert a Levels adjustment layer (or a Levels adjustment) to a Curve?  I seem to remember such a feature in an old version of Photoshop, but I cannot find it in Photoshop CC. 

Such a feature would have tremendous educational value for the course I'm teaching because most students don't understand how the two adjustments are related. It would also have practical value, since you may want to tweak a Levels adjustment (layer) in a way that is only possible in Curves.  Naturally there is no way to go back to Levels from Curves!

If the feature does not exist, I will post it as a feature request.

This topic has been closed for replies.
Correct answer Jeff Arola

In photoshop you could use this script to generate a curves adjustment layer from a levels adjustment layer, save out the generated curves because the script creates a separate document with the curves layer and then open a curves adjustment layer in your original and load the saved curves layer.

You could also just duplicate the generated curves layer to your original document.

Not as fast or straight foreword as Gimp, but it does work.

http://www.tonton-pixel.com/blog/scripts/creative-scripts/combine-adjustment-layers/

3 replies

Jeff Arola
Community Expert
Jeff ArolaCommunity ExpertCorrect answer
Community Expert
February 4, 2017

In photoshop you could use this script to generate a curves adjustment layer from a levels adjustment layer, save out the generated curves because the script creates a separate document with the curves layer and then open a curves adjustment layer in your original and load the saved curves layer.

You could also just duplicate the generated curves layer to your original document.

Not as fast or straight foreword as Gimp, but it does work.

http://www.tonton-pixel.com/blog/scripts/creative-scripts/combine-adjustment-layers/

J
J IsnerAuthor
Inspiring
February 4, 2017

That is an amazing script!  I installed it and it works.  For my purposes this will do just fine.   Thanks for posting!

Benjamin Root
Benjamin Root
Legend
February 4, 2017

I'm not aware of any such feature. Instead, why not:

  • Add a Levels adjustment, set White and Black points to value
  • Ctrl + Alt + Shift + E to Stamp visible.
  • Move new layer to down below all others.
  • Make a Curves adjustment, set White and Black points to Levels' values.
  • Stamp visible
  • Bring the Levels stamp visible layer up, one below Curves' Stamp visible.
  • Toggle top layer's visibility on/off to demonstrate both are identical.
J
J IsnerAuthor
Inspiring
February 4, 2017

I'm not interested in how to do it.  I know how to do it.  I'm interested in a feature that does it automatically.  As I said in the OP, such a feature would have pedagogical value, but probably not much practical value.

Terri Stevens
Terri Stevens
Legend
February 4, 2017

I like your idea, but as Benjamin says it doesn't exist in Photoshop and probably for good reasons. What you are asking is for 3 parameters to somehow be converted to 25 (or whatever the max current number of curves points is). How can an algorithm decide that distribution of values beyond the black and white point? I think students should be taught the significance of input and output values and understand digital imagery that way. If you just give them an easy button to press they still won't have a clue as to what is really going on.

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    February 4, 2017

    Turn off the visibility of the Levels adjustment layer and add a curve adjustment layer.  They work differently IMO  one can not be converted to the other.  While a curves adjustment adjust images levels it  can adjust levels differently then levels not evenly across the image like levels.  A Curve adjustment can adjust levels like the levels adjustment when it applies the levels without using a curve its default diagonal line a linear adjustment.

    JJMack
    J
    J IsnerAuthor
    Inspiring
    February 4, 2017

    I understand how to achieve the effect of a given Levels adjustment using Curves.   What I asked about is whether an automatic conversion from Levels to Curves exists in Photoshop CC.

    I respectfully disagree with two of your statements.

    • Levels CAN always be converted to Curves (but not vice versa)
    • Dragging the midtone slider in Levels produces a non-linear curve.

    For example...

    is equivalent to

    JJMack
    Community Expert
    JJMackCommunity Expert
    Community Expert
    February 4, 2017

    I can not believe can make a level adjustment that is like every curve adjustment that can be made. equivalent to any curves Curves  can be very complex.

    JJMack
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