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Jan 10, 2012

The Secret Behind Levels VS Curves in Photoshop

Why Curves and Levels Are Important

Curves and Levels are the bread and butter of photo editing, but it can be difficult to know which one to use. Today we analyze both, and give the strengths and weakness of each. I also cover when I use levels and when I use curves, and how to make the process more simple.

Today’s Episode Timeline

  • 0:03 – Adjustment layers are like Jelly Beans
  • 1:30 – What Curves and Levels have to do with editing.
  • 2:40 – Overview of when I use Curves
  • 3:15 – Overview of when I use Levels
  • 4:40 – Explaining input and output levels
  • 7:00 – Showing the parallels between levels and curves
  • 8:20 – Drastic changes with Curves
  • 9:30 – How to make Curves very user friendly
  • 13:30 – Choosing your black point, grey point and white point.
  • 14:00 – A great tip for people who shoot with a grey card
  • 13:30 – Choosing your black point, grey point and white point.
  • 16:30 – Teach me something about Curves and Levels

What to use if you don’t like graphs

There is a hand tool in the curves adjustment layer that will allow you to click directly in your image and change your values and colors based on where you click. It takes all the technical stuff out of editing, and just leaves the fun. Highly suggested.

Curves

In general, curves are a bit more user friendly, and will allow you to make more dramatic changes than levels. With the ability to change things drastically comes the ability to either really mess an image up, or make it great.
Here is when I will use Curves

  • Adjusting the colors of highlights, mid-tones and shadows
  • Adjusting very specific values (Using the Hand)
  • Creating Vignettes (Pull RGB up in center slightly)
  • In compositing, often you will need to change colors, lights and darks to make an image fit. Curves handle this very well
  • Making drastic changes

Levels

Levels are perfect for large global adjustments such as making the lights of an entire image a little less bright. They are a bit more subtle than curves.
Here is when I use Levels

  • Making subtle changes
  • Adding slight color to highlights and shadows (as depicted in the image be Annie Leibovitz below)
  • Making white leves slightly darker so things don’t look blown out

46 Comments


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  • Ronny

    Hey Aaron, I am very new to phlearn and I am very happy I found you guys! You are doing an incredible job, the tutorials are high end and entertaining to watch, I was even surprised to see that the photography tutorials are actually great, you really know your stuff! So I’ve been watching your tutorials in photoshop and am very pleased to learn a new technique or approach in almost every single one of them. And although I consider myself a pro in everything considering realistic related in photoshop this site gives me the great opportunity to expand my knowledge to effects and fantasy composites from someone who actually knows his stuff! Awesome!
    I am actually considering purchasing a pro tutorial or two in the fields I am lacking but I am finding it a bit difficult to choose since there is not much detail of what’s inside the tutorials.

    Okay so the reason I am actually commenting is that I have the opportunity to phlearn you, as you asked us viewers to do regarding the curves (and i guess this also applies to levels) adjustment layers.
    Well first of all, curves (and levels) as you showed treat different channels and also all of them together which is what people use to adjust their light contrast. But, as those channels change the light they also automatically change the colors! So here I use blend modes to take control over these things. For example, if i want to change my lighting contrast I use the blend mode “luminosity”. This allows me not only to change the contrast and not touch the colors while i’m at it but also to use the individual channels for different strengths of contrast. RGB mode does very harsh contrast and sometimes you want to just do subtle work, you know you’ve taken your photograph quite well and now you just wanna touch that extra 2% to make it perfect. So basically and typically the green channel holds most of the light information in the image and you can use that channel to make big changes. The red channel is kind of the ‘medium’ information channel which I personally use the most, the changes there are much more subtle and none destructive as the green or RGB obviously. And finally the blue channel holds very little information and is best used for extreme delicate changes or atmosphere adjustment to the image while pulling the mid point up and down. I also find the blue channel useful for adding mid tone contrast that is similar but a bit different than clarity or high pass results and makes things kind of look more 3d.

    Furthermore the curves and levels can be happily used in color or hue blending modes. This I find, is actually a far more accurate way to play with saturation than the hue saturation adjustment layer since you can control exactly which type of color tint to adjust etc.
    Also you can lower the black point by taking a curve layer and set it to multiply very easily and quickly and also screen you know, the opposite. So yeah, blend modes and adjustment layers! Powerful stuff!

    Hope I phlearned you :) Ronny Izsak.

    • Ronny

      Oh yeah, one final note, I actually do use sometimes the white and dark point clickers in the adjustment layers. The thing is sometimes you have a bad exposure and this is a great way to change things seamlessly. So for example I can use the threshold adjustment to find my whitest and darkest points and mark them and then turn them off and in the curves/levels layer double click on the white point clicker which will open this dialog like the color palette. There I sample the point that I marked as white and under L A B (to the top right) change the L for the light point. Lets say I measured 87 and as my lightest point I can then click something like 96/97 which is usually good and click ok. Then use that picker to click on the lightest point in the image and it will adjust the image lighting seamlessly (of course the same goes to the dark point). And if I don’t want this to effect the contrast of my colors I can easily change the blend mode to luminosity.

      P.S. I noticed you use a lot of high pass for sharpening and you desaturate the layer to avoid changing the colors. Now this is great for high pass but if you want to use unsharp mask which gives you a bit more range of results you can keep the image colorized and just change the blend mode to luminosity. Then to make final adjustments use blend if incase your highlights or shadows went to the extreme. (or stamp the result and duplicate, make one lighten one darken and play with the opacity. I personally find blend if to be simpler and more efficient).
      So thanks again for all your hard work and i’ll phlearn you later!

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    Kyle Anderson

    Aaron, good news and bad news: you were right, Spider-man’s uncle’s name was Ben. But the quote was from Aunt May when Peter is trying to balance his regular life and his secret, super hero life.

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    Lorna's Lens

    I am a curvy girl, however I don’t know why but when I select curves via my moon (at the bottom of the layers palette) , it sometimes brings up levels instead and then I have to go to adjustments to grab my curves. I do open/close ps and sometimes that helps. I wonder why it’s being naughty like that! Love the explanation here Mr Nace and I love your big yellow A.

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    creativenomad

    thisis brilliant thanks so much! I would of never known about this hand trick thanks

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    Jared Carpenter

    I like to use levels at the beginning to set my, well, levels. I mainly just use it to be sure that my histogram is full so that my whites are white and darks are dark. (which shouldn’t be a problem if I shot the image correctly ha). At the same time I have used it to blow out an image as well for affect.

    Sometimes I will set my levels with curves but I like to have a fresh curves pallet for making my adjustments so I leave the levels on its own adj layer. I mainly use curves for contrast adjustments and as Jenna Petrone made a point of, for locational adjustments.

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    Spy Black

    People who don’t know how to effectively use adjustment layers should not be giving tutorials.

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      Jared Carpenter

      Hey, we’re all here to hopefully learn. Could you please explain to me exactly what the difference is between gamma and contrast as I am a bit foggy there. Thanks!

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        Spy Black

        With levels, contrast is the adjustment you make when you adjust the black and white input level point data in or out, the effect is especially obvious when the two are adjusted together. Gamma is when you adjust the midpoint data lighter or darker. While they may seem similar, they are not. Gamma is not contrast, and contrast is not gamma.

        Also, dropping the white or black output levels as was done in the examples means you are clipping ALL white or black point data out of your image. You can’t get any white or black point data back regardless of what additional gamma or contrast settings you make. This may be handy as an effect, or to avoid total ink in a press run (with the black output setting, and you should have an accurate proofing system to get it correct) but in day-to-day retouching this is otherwise going to give you pretty nasty results. Try it.

        I suppose I was a bit too harsh there in my initial comment, but the moment he clicked on the gamma setting and called it contrast, my eyebrow certainly went up!

        • Ronny

          I must’ve missed where he clicks on gamma since i was doing some printing (although i cannot imagine where the gamma settings is on curves or layers).
          Anyway, I’d like to correct your statement that gamma is a midpoint adjuster. I don’t know how to describe gamma precisely but vaguely I can tell you that this term describes the range between the black and white point, and the black point value. (This term was born if i am not mistaken in negatives, some negatives came with 2.1 gamma and some with 1.9 and the photographer could choose which type of negative to use according to the contrast they desired). I personally never use the gamma adjustment in the exposure adjustment layer. What I do for gamma changes is create different color profiles to grab different gamma outputs from there to my images (copy go back with history and paste on my working color profile). This is the best fix I know for heavy darks for example, something that cannot be achieved by curves or layers in a million years. It gives you a great result going up the exposure from dark to mid tone to white, while barely if not at all changing the values above the actual gamma set (i.e. highlights stay the same etc..). I will add an example of a restoration with gamma changed color profiles as an image.

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    Erica DalBello

    Hi!! When I want fast add contrast, I use Levels. But often I use Curves, because for me its more accurate with details. Actually I love curves! hehehe and thanks for your tutorial, fun and very well explained. ^^

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    LovelyLo

    Ive always used Levels because I dont think my Elements 9 has curves. But if anyone knows if it does, let me know! Becaus eI cant find it. Haha :)

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      Eric

       In case no-one has replied to you: Elements has curves…after a fashion. It is under Adjustments-Adjust Color-Adjust color curves. Ironically, you cannot directly adjust color here. You are only offered sliders which are really quite similar to the Highlights/Shadows adjustment, except you get a graphic of a curves chart showing you the effect. Hope that helps.

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    23X

    I use the levels adj layer, frequently if not always. I use curves very sparingly because I don’t seem to be able to control it as well. 
    For tones only! Occasionally I will use a color balance adj layer when I see too much, I dunno, magenta in my image. I have not eaten a jelly belly in about 26 years due to the fact that my first job was in a bulk food store and I spent a lot of time scraping them off the floor.

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    Andrea Peipe

    I must have not been on for quite a while, have not even seen your new haircut ;)

    Funny but in the beginning I only used curves and now I mostly use levels! I find that levels are more accurate because like you said, you can mess your photos up more easily with curves. But I will use curves again more in the future after this :D The hand is awesome!! I had no idea it existed!

    P.S. That was awesome :D

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    Sebastian Ortiz

    OMG!!!! I LOVE BUTTERED POPCORN JELLY BELLY’S!!!!!! HA! 
    MY FAVORITE!!!! I thought I was the only one, I knew, that loved the Buttered Popcorn… LMAO !

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    Erika Edgerley

    Thanks for this! I’m curious though, is there anything that you can do with levels that you can’t do with curves? I find that I generally just use curves as, like you said, it’s more user-friendly, and it allows me to make both subtle changes as well as big changes.

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    CEBImagery

    I always start by using levels and holding the option button and moving my white are dark sliders to find my whitest and darkest points upon which i’ll then set those points via my black and white eye droppers.

    I’ll then create another levels adjustment layer for just using my grey eye dropper and loom at my info screen for color values across all three channels from the 50’s-130’s to see if I find a mid point i like. Sometimes it doesn’t work and I can just delete the middle grey adjust menet layer.

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    André Borgen

    Hi great video! can you show us how to use calculations so we can get perfect layer masks, especially when it comes to hair on a low contrast background… Don’t think you have mentioned that feature in PS??

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    Michael Vinson

    That was a great tip about using Levels and adjusting the Output Levels when printing. I’m going to use that next time I print out some proofs. Thanks

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    Jenna Petrone

    I use curves for everything. I used them in depth last semester while editing my black and white 4x5s.  I would watch one area of a picture I want to fix while playing with the curves, find what I want, put a black layer mask on it and paint it with white.  I’ve used curves like that ever since.  One thing I didn’t know about was the little hand on the top left hand corner, that’s really cool! I feel like there’s so many little tricks in photoshop that I don’t even know yet.  I want to get more used to using levels though, it will really help me out in the long run.

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    janiecakes

    Great explanation. I have never really known how to use these tools and basically just mess around with them until I get something I like.  Very useful information. Thanks Aaron.  Thanks for the laughs too :)

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    Daniel Tuck

    I have a quick question about Curves Adjustment Layers – for some reason the channel drop-down on the adjustment panel becomes disabled, so I can’t switch from RGB to Red, Green or Blue. Anyone know why this happens? When it does it, if I select a different Curves layer which previous worked, I still can’t select from the drop-down! Don’t know if this is a bug, or something about the document I’m editing (it’s happened on several files now). Anyone else experienced this? Thanks :)

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      Aaron Nace

      very weird Daniel, have you tried resetting photoshop?? http://www.lancelhoff.com/how-to-reset-photoshop-to-default-settings/

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        Daniel Tuck

        Thanks for the tip Aaron – I’ll have to give it a go. It doesn’t happen very often, and restarting Photoshop solves it – just thought it might have been something within the document that was causing trouble.

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          Eric

          Daniel, I had the exact same thing happen to me yesterday. Closing and restarting fixed it, but it’s annoying just the same. BTW: I’m using CS5.1/WinXP(32).

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    James Warwood

    Great episode! I’ve only really used levels before for slight contrast adjustments to landscape shots. I’ve always been slightly reticent about using curves, mainly due to not been 100% sure on when is best to use them. So thanks for the tips! Working on a composite at the moment so my aim is to use curves as much as possible in this to get a better understanding of them.

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    Photographybymel

    I hope one day I can teach you something about photoshop. That would be really cool. As for now, my head is just spinning with this constant new information you are giving me. I am so grateful I have found your tutorials. Thank you!

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    Tia GliUseless

    Tip: you can delete single points in the curves even clicking on them holding ctrl (that is faster than dragging  them outside the graph, in my opinion) :)

    Great episode by the way, I’m never sure about the difference in output and input in levels, and you helped me a lot :D

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    Gixster92

    Great video… .I LOVE LOVE LOVE my curves.  I will do a curve adj layer and look at only ONE spot I want to change and then mask it for just that spot.  I also do curves to brighten my eyes iris by lowering the white on the curve and make blending mode screen and another to darken the parts of iris by upping the dark point and blending mode of soft light….. giver a try…. I don’t know a better method to pop my eyes on portraits.

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    Mark ODonnell

    Uhm, did you just throw your Wacom Pen?  That made me cringe ;-)
    I use gray cards all the time.  It’s an essential part of my work flow with color calibrated monitor, and ICS profiles for printing.   Especially handy when photographing food!
    I’ve never checked but can you still edit curves and levels when using smart layers?