How To Use Curves in Photoshop
If I were forced to give up all but one image adjustment tool, I would keep curves. Hands down. The curves adjustment tool is an integral part of every professional’s knowledge base and image editing package.
Even if you’ve taken a good photo, chances are it can be improved or it needs to be adjusted to work in a collage or collection. Or even to just to intensify a mood. You can always make a good thing better – and curves is a one-stop-shop way to do that.
With curves you are able to:
- Adjust the over-all contrast or tonal range
- Adjust the local contrast or tonal range
- Adjust the color
Let’s jump in and find out how. It’s simpler than it looks.
Overview
The idea behind Curves is all about re–mapping values. A pixel starts out at a certain brightness, and you change it to be brighter or darker.
The curves box opens as a straight line because you haven’t made any changes yet. That means that the brightness values before and after are the same. You will effect a change by changing the shape of the curve.
The points from left (bottom) to right (top) affect: blacks, shadows, midtones, highlights, and whites. By altering the position in these regions will affect the corresponding tonal range of your image. Leaving the line in the center will leave the tones unchanged.
You begin altering the brightness values by clicking once somewhere on the line. This will establish a “point”; this point can now be dragged to a different place within the grid, which causes that tonal value to change, either lighter or darker depending on whether you drag it up or down. The reason it’s a curve is so that the change blends smoothly throughout the image. An abrupt change in value can be very noticeable. The increasingly gradual change of the brightness values on either side of the change permit a very smooth and believable adjustment.
It’s important to note, however, that you can’t increase contrast in one region without decreasing it in another. The curves tool redistributes contrast. Therefore think of the image having a contrast allocation or budget and you need to decide how to best spend it.
Also, the curves tool will preserve the tonal hierarchy (unless you use uncommon negative slopes). That means that the brighter parts of the image will stay brighter even after your conversion – just maybe not by the same amount.
Quick Tip
Keep effects on adjustment or separate layers to enable quick alteration or removal at any time during the color correction process. (Layer > New Adjustment Layer > Curves. Or at the bottom of the Layers panel.)
S- and Inverted S-Curves
Rollover Image
The S-Curve and the Inverted S-Curve are two curves most commonly used. The S-Curve adds contrast to the midtones while subtracting from the shadows and highlights. The Inverted S-Curve does the opposite.
Often in photography, it’s difficult to expose your image perfectly. Brightness or darkness in tonal ranges can benefit from optimization. The S-Curve is often useful in these cases – not to mention, quick and simple.
Empty Tonal Range and Histograms
Rollover Image
One very useful and important function of curves is to correct empty tonal ranges – in the histogram edges (blacks and whites) or gaps in between (shadows, midtones, and highlights). An under exposed image can be helped by pulling in the black and white points to correct the exposure.
Or if there are gaps in between the tonal peaks you can decrease contrast in specific parts of your image – thereby freeing up the contrast to be used in the more visible areas of your image.
Clipped Highlights
Rollover Image
Images containing a bright light source, such as the sun, can often be harsh or posterized (also called color banding). Posterization of an image entails conversion of a continuous gradation of tone to several regions of fewer tones, with abrupt changes from one tone to another. This can create an unrealistic look, and often a smoother transition to white is preferred.
Correcting Color Balance
All curves thus far have been applied to RGB values of luminosity. But they can also be used on individual color channels to correct color casts in specific tonal regions. Often the color in an image is correctly balanced, but due to reflection or a light source with a varying temperature or color, you may see unwanted tints in a tonal region. Changing the white balance or adjusting the overall color would inadvertently harm the other tones. So we can selectively increase or decrease the amount of a color cast in the red, green, and blue channels to achieve perfect balance.
Any adjustments upward of the diagonal line in the red channel increase the red in the image. Lowering, below the diagonal line, increases the cyan. The other channels are the same: Upward in the green channel, green; lower, magenta. Upward in the blue channel, blue; lower yellow.
RGB color images should be thought of as being comprised of a composite channel and three grayscale channels containing the values of the three colors – red, green and blue. This is shown in the example above of the red on the left, green in the middle, and blue on the right.
Window > Channels to see this on your image.
Rollover Image
You can see in the image above that there is a slight blueish cast in the color tone. Not to mention, the image is slightly washed out (improperly exposed).
As you can see, the sky is already quite white, so we won’t want to effect the highlights and above. By lowering the curve in the midtones and shadows, without effecting the highlights, we solve the exposure problem. Then we’ll get rid of the blue color cast: By lowering the blue in the low end, we eliminate the problem and the gowns go to black – as they should be.
Note
If precise color adjustments aren’t required, simple color balance correction might be easier (Image > Adjustments > Color Balance).
Blending Modes
Also, curves adjustment layers (Layer>New Adjustment Layer> Curves) can be set to make curves only apply to a channel – such as Color and/or Luminosity – which allows for further, varied control. Another benefit is that it can make your adjustments more subtle through use of the opacity controls for the layer.
Notes
Practice makes perfect. The more you use the tools and techniques available to you the better you’ll get, improve your photography, and have fun.
Here are some things to remember when using the curves tool:
- Minimize use of the curves tool, as anything which stretches the image histogram increases the possibility posterization.
- Avoid the use of the curves tool on an already altered image.
- Perform curves on 16-bit images when possible. (Image > Mode > 16 Bits/Channel)
- For extreme levels of color correction, consider applying curves using LAB mode.
161 Comments
Help, my photoshop 7.0 has started giving me a pencil instead of a cursor in the curves window. The slider line is just cut by the pencil and the line doesn’t curve. I can’t find a way to get back my old cursor. I reinstalled photoshop and that didn’t fix it. Is there a preference that may have changed?
Flag as inappropriatePlease fix the rollover image problem. Not working!
Flag as inappropriatePhotoshop tutorials, from beginner to advanced. photo manipulation, icon design, text effects, interface, layout, painting, photo effects, psd tuts, maxon cinema 4d, designing.
Flag as inappropriatehttp://photoshopcs8.co.cc
Rollovers not working. I tried Chrome and IE.
Flag as inappropriateHi
Flag as inappropriateNice
hey Good tutorial, keep writing mor tt
Flag as inappropriatethanks
very Nice TNX !
Flag as inappropriateVery good article and expressed fantastically…! :)
Flag as inappropriateBrilliant, thank you.
Flag as inappropriatehey,that was a amazing article about curve..thx….
Flag as inappropriateIn this photoshop tutorial we will learn to design a clean website layout. … This photoshop tutorial show you how to design a very beautiful and shining …
Flag as inappropriatethanks.. find more best tutorials here http://newsclub1.com
It’s nice to see tutorials like this. We are so use to seeing tuts on creating cool buttons, icons, web layouts, posters and more.
We can’t forget the basics and what PS was originally built for.
Nice stuff guys
Flag as inappropriateVery helpful!
Flag as inappropriateRegistered members can do
Flag as inappropriateCurves are important in Photoshop, thanks for the tutorial!
Flag as inappropriateGreat Advice. Thanks
Flag as inappropriateThnx really useful!
Flag as inappropriateAn absolutely fantastic tutorial, thanks for sharing!
Flag as inappropriateThanks! I use Curves but a bit haphazardly…love your precise fixes and your clear example images. :)
Flag as inappropriateThe easiest way to understand PS curves I’ve ever seen! Thanks for sharing.
Flag as inappropriateThanks so much!! I’ve been wondering about these for the longest time…
Flag as inappropriateI love you man. You’re Real
Flag as inappropriateWHOIS lookups were traditionally performed with a command line interface application
Flag as inappropriateThank you! Very useful tutorial!
Flag as inappropriateThis was an incredibly helpful tutorial! I accidentally used curves once and had no idea what I was doing. I’ve never used it since for fear of ruining my image! Thanks for the wonderful explanation!
Flag as inappropriateGreat explanation on this wonderful tool. I will follow your instructions on some photos tomorrow
Flag as inappropriateGreat stuff.
Flag as inappropriateTHIS… is wonderful…. THANK YOU!
Flag as inappropriateThat’s crazy!
http://tweekhub.com – All your friends are doing it.
Flag as inappropriatevery helpful tutorial, i didn’t know Curves so much!
Flag as inappropriateGood tutorial on curves! If only it was that well explained years ago, thank you:)
Flag as inappropriatewow, amazing. thanks for sharing.
Flag as inappropriategreat great tutorial ,thanks alot
Flag as inappropriateNice information about the Photoshop curve, amazing!
Flag as inappropriateCongrats for the autor!
hey thanks a lot…..cudnt make head r tail of those curves b4 this
Flag as inappropriateThanks for taking time and sharing your knowlage,we need your tuts,
Flag as inappropriatePerfect! Ive been looking for this exact article for a long time! Thanks for taking the time to do it!
Anthony Pittarelli
Flag as inappropriatei work largely in Adobe After Effects, and i always fiddled with curves, but now it makes sense! Thanks
Flag as inappropriatethanks for this advise
Flag as inappropriateAwesome tutorial! thanks for sharing
Flag as inappropriateThis is a very helpful article. Thanks for publishing and making curves a lot easier to understand.
Flag as inappropriateNice tutorial, really useful for tweaking photos.
Flag as inappropriateOh thank you a site that has explantions i can understand on photo shop!
Flag as inappropriatewoooohooo!
Nice explanation of curves. I learned some good information! Much appreciated!
Flag as inappropriateOwen, I just wanted to say that I really enjoy your direct and understandable way of writing/teaching. :)
Flag as inappropriatefantastic…i will fun to learn…thanks
Flag as inappropriateSimple and to the point. Nice job.
Flag as inappropriatePedagogic article, good examples. The clipped highlights example was very interesting!
Also, I’ve never really thought of using different blending modes on curve layers, that is something I’m going to experiment with.
Flag as inappropriateGreat and easy steps! TK!
Flag as inappropriateSo simple,so important!
Tk,Tk, Tk!
Hi there and thanks for the great article.
Flag as inappropriateWhat would you recommend for adjusting product photographs of black objects. They all look like black blobs, and we want to show the detail in the products, which are camera bags.
We are now adjusting the curves, and using channel mixer also. Any suggestions? We have hundreds of photos to retouch.
Thanks, Jan
Hey, Janis.
Flag as inappropriateSend me one of the pictures you’re talking about and let me know what you’re trying to accomplish. I can edit it and see what I can do to give you an example for it or send you the processes.
Cheers.
I will like to try… i am a beginner… as many
Flag as inappropriateThanks
Thanks for demistifying the curves app for me
Flag as inappropriate刘苏到访，留个脚印…
Flag as inappropriatethis has been great help Thanks Man!!!
Flag as inappropriategreat information im currently looking for help and this has been more useful than i could imagine.
Flag as inappropriateThanks alot!!!
I’m a beginner. Everything is useful.
Flag as inappropriateAlways shy away from using levels, but will attempt to use them now. Thank you Owen, great tutorial!
Flag as inappropriatevery informative, thank you for sharing this! I’ve been using Curves on Post Processing, this is very helpful!
Flag as inappropriateVery good tutorial, I’m new at this site and just picked up the link from facebook and I think it was the best thing I did today. Thanks and keep in touch, please.
Flag as inappropriateNice post!
Flag as inappropriateVery nice and good tutorial for beginners.
Flag as inappropriateI use curves all the time…the simple s-curve can make all the difference.
Flag as inappropriateGood tutorial, there is so much more to photoshop than I commonly use.
Flag as inappropriateFinaly I know how to use curves… thank you :D
Flag as inappropriateAgreed :)
Flag as inappropriateVery useful for beginning photoshoppers!
Flag as inappropriateThank you. I used this technique in my blog.. Thanks a lot…
Flag as inappropriatevery useful post, helped me alot
Flag as inappropriatei have learned a lot fro here. previously i had knowledge about curves thanks to adding more info about curves. it helps me a lot in adding a knowledge to me.
Flag as inappropriatevery nice post indeed….i didn’t know Curves could do so much!
Flag as inappropriateVery nice post, we are loving CS4 at Tidy Design… Keep these great tutorials coming! :D
Flag as inappropriateThis is an awesome post!!!!
Flag as inappropriatenice!i love it
Flag as inappropriateReally great handling of examples!
I could instantly appreciate the purpose of curves in photoshop. :D
Flag as inappropriatetell you the truth. these curves are difficult to handle. for me at least. thanks for these great tips
Flag as inappropriateSimple yet important topic explained.. Wow
Flag as inappropriateone of the best tutorials on such topics
Flag as inappropriatethanks very much
Well written tutorial. Thank you!
Flag as inappropriategreat tutorial.
i like it.
thanks
Flag as inappropriateThanks for the tutorial! I had always just blindly adjusted them hoping for the desired result or avoided using them altogether.
Flag as inappropriateThanks for the tut! I got in to curves via trial and error, this really explained the why for me :) Thanks!
Flag as inappropriateGreat tutorial, I like many others wasn’t overly sure how it all worked, so this is great for me.
Flag as inappropriateThanks and Good explanation. I think I use curves on every design I do. Curves works well for things other than photos too, textures can have a whole new life with some curve adjustment. After I do a design I will sometimes add a curves adjustment layer to the whole thing to get a much more rich looking design.
Flag as inappropriateGreat tutorial one of those function I know existed but never really used because I or didn’t know how to use, or just never needed. Now I’ll be taking a much closer look at it, thanks.
Flag as inappropriateSimply fantastic and easy to understand. Thanks a lot!
Flag as inappropriateNever used curves before, but I can see it having a huge benefit to some of my pictures.
Thanks for this, tutorial9!
Flag as inappropriateI always did the same thing as Kevin Barney a few comments above me. But never understood WHAT exactly happend with my pictures. Thanks to this turorial I know a lot more about curves. Very well writen two!
Flag as inappropriateThank you very much :)
Great, well thought out and explained tutorial. I’ll definitely think more before using curves from now on instead of just randomly moving stuff around!
Flag as inappropriateThanks for the tutorial. There are a couple of methods here I was not aware of and will definitely be using.
Flag as inappropriateThe rollovers aren’t working for me. I use Google Chrome.
Other than that, great tutorial!
Flag as inappropriateWhat ? i too use google chrome y visualize good :-)
Flag as inappropriatethanks
Flag as inappropriateVery well explained! No matter how good is your photo, the curves tool will make it look a lot better. Thank you for this and all the tutorials on Tutorial9!
Flag as inappropriateI think this is one of the best tutorials/articles on Tutorial9! Also the best explanation of curves I’ve seen so far. Really great!
Flag as inappropriateGood stuff. I’ll be back
Flag as inappropriateWell done on this tutorial. You have made curves very simple to understand.
Flag as inappropriateI agree with the others; now, instead of randomly moving points along curves until I think I see what I like, I’ll have a much better idea of what is going on! Thank you for the well-written explanation!
Flag as inappropriateI’ve always just flung the curves around without much care for where they went, checked the preview, and then moved them about some more if I didn’t like the way it came out.
I’ve never taken the time to sit down and figure out why what happens does; this tutorial made it pretty clear. Thanks for explaining things and putting me on the right track.
Experimentation is good, but it’s better to have at least a hypothesis going in. =)
Flag as inappropriateInteresting Tut. Thanks for this well explained tutorial.
Flag as inappropriateVery well written tutorial. Thanks
Flag as inappropriateThis is the best explanation of curves I’ve ever read. Thanks!!
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Flag as inappropriateGreat tutorial, learned a lot here
Flag as inappropriateI too ;-), very good Owen James, thanks friend
Flag as inappropriate