Mimicing Levels in Curves...?

Denis Mortell

• 27. Juli 2019 09:03

I would like to be able to mimic the effect of Levels in Curves.

The reason I want to do this is that C1 does not offer a Luma option in Levels, and I want to make a contrast adjustment, setting shadow and highlight points, but without affecting RGB.

So, does the following make sense?

1. Set shadow and highlight points in Levels.
2. Make a note of the values.
3. Reset those levels to 0/255.
4. Select Luma in curves.
5. Drag to shadow and highlight to the values noted from Levels.

Now, do I have pretty much the same thing, but without any RGB change?

Thanks.

D.

0

• 

  Ian Wilson

  Moderator

  • 27. Juli 2019 10:00

  

  Apparently it does have the effect you want. I've just tried it on 3 variants of the same image. The image in question went all the way to the left on the histogram already, so I only adjusted the highlights end.
  
  Variant 1: I pulled in the highlights point on Levels to the edge of the histogram: 210 in this instance.
  
  Variant 2: I pulled in the top right point on the RGB curve to where the box read 210.
  
  Variant 3: I pulled in the top right point on the Luma curve to where the box read 210.
  
  Result: to me eye, Variant 1 and Variant 2 look identical in contrast and colour. I notice no change at all switching from one to the other. Variant 3 looks less saturated.
  
  So if you like you could do it that way.
  
  One the other hand this rather assumes that you are not going to be touching the saturation control anyway. I tend to use the levels tool before I adjust saturation, so I end up increasing or decreasing saturation to taste at some stage in the process. And if you use the curves tool for levels, you can still adjust the curve but perhaps your options are a bit more limited than they would be otherwise.
  
  Images below. The lower saturation in number 3 is especially obvious in the reddish colour of the wood to the right of the padlock.
  
  Ian
  
  https://live.staticflickr.com/65535/48386089751_4f1eaa8e21_z.jpg

  0
• 

  Denis Mortell

  • 27. Juli 2019 10:40

  Ian,
  
  Thanks.
  
  Useful for some of what I do.
  
  D.

  0
• 

  Denis Mortell

  • 27. Juli 2019 12:12

  Ps.
  
  Since doing this in Levels causes an RGB shift; does a Saturation tweak correct the shift you’re seeing between Levels and Luma Curves?
  
  Thanks.
  
  D.

  0
• 

  Ian Wilson

  Moderator

  • 27. Juli 2019 13:32

  

  Interesting question.
  
  I've tried this with my Variant 3. Pulling the saturation slider up to about 17 or 18 gets me pretty close to the saturation of Variants 1 and 2. But I can't make it look completely identical with just the saturation slider - there is a slight difference in brightness. But 17 on the saturation and +2 on the contrast slider looks pretty close, though not identical. I could also play with the brightness slider, but I haven't tried that too.
  
  Try it for yourself and see what most easily gives you the results you like.
  
  It all goes to show that there is more than one way of getting to a look you like - for example brightness can be affected with the brightness slider, the middle control on Levels, pulling up the curve slightly, or pulling up mid-tones on the colour balance tool. They all do a similar thing, but with subtly different results.
  
  Ian

  0

Post ist für Kommentare geschlossen.