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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

Image Description

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.

Image Description

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.

Image Description

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

Image Description

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

  1. Add point Subtract point

    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?

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  2. Add point Subtract point

    Please fix the rollover image problem. Not working!

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  3. Add point Subtract point

    Photoshop tutorials, from beginner to advanced. photo manipulation, icon design, text effects, interface, layout, painting, photo effects, psd tuts, maxon cinema 4d, designing.
    http://photoshopcs8.co.cc

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  4. Add point Subtract point

    Rollovers not working. I tried Chrome and IE.

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  5. Add point Subtract point
    black.friday.boys (2 Points) November 10, 2010 at 9:51 am

    hey Good tutorial, keep writing mor tt
    thanks

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  6. Add point Subtract point
    M THomas (0 Points) September 14, 2010 at 7:49 am

    Very good article and expressed fantastically…! :)

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  7. Add point Subtract point
    maruf ahmed (1 Point) August 26, 2010 at 12:46 am

    hey,that was a amazing article about curve..thx….

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  8. Add point Subtract point
    roneybalack (1 Point) August 8, 2010 at 3:44 am

    In 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 …
    thanks.. find more best tutorials here http://newsclub1.com

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  9. Add point Subtract point
    PSD Style (1 Point) August 5, 2010 at 9:38 am

    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

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  10. Add point Subtract point
    donghongguang (0 Points) July 8, 2010 at 9:31 pm

    Registered members can do

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  11. Add point Subtract point
    Chris Miller (1 Point) July 2, 2010 at 2:08 pm

    Curves are important in Photoshop, thanks for the tutorial!

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  12. Add point Subtract point
    LearningTheLight.com (1 Point) June 28, 2010 at 7:00 am

    An absolutely fantastic tutorial, thanks for sharing!

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  13. Add point Subtract point
    Esther (1 Point) June 23, 2010 at 1:58 pm

    Thanks! I use Curves but a bit haphazardly…love your precise fixes and your clear example images. :)

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  14. Add point Subtract point
    Otacílio Rodrigues (1 Point) June 23, 2010 at 12:40 pm

    The easiest way to understand PS curves I’ve ever seen! Thanks for sharing.

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  15. Add point Subtract point

    Thanks so much!! I’ve been wondering about these for the longest time…

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  16. Add point Subtract point

    I love you man. You’re Real

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  17. Add point Subtract point
    algdfa (1 Point) June 16, 2010 at 4:06 pm

    WHOIS lookups were traditionally performed with a command line interface application

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  18. Add point Subtract point
    IGuAn (0 Points) June 16, 2010 at 12:54 pm

    Thank you! Very useful tutorial!

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  19. Add point Subtract point
    Sophie (2 Points) June 2, 2010 at 1:40 am

    This 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!

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  20. Add point Subtract point
    David (1 Point) June 1, 2010 at 8:53 pm

    Great explanation on this wonderful tool. I will follow your instructions on some photos tomorrow

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  21. Add point Subtract point
    Mike (1 Point) May 30, 2010 at 2:38 pm

    THIS… is wonderful…. THANK YOU!

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  22. Add point Subtract point
    Tweek Hub (1 Point) May 29, 2010 at 6:47 pm

    That’s crazy!

    http://tweekhub.com – All your friends are doing it.

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  23. Add point Subtract point
    Clickbank Directory (1 Point) May 29, 2010 at 6:29 pm

    very helpful tutorial, i didn’t know Curves so much!

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  24. Add point Subtract point
    Photo Restoration (1 Point) May 29, 2010 at 12:49 pm

    Good tutorial on curves! If only it was that well explained years ago, thank you:)

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  25. Add point Subtract point
    Kaleem Akhter (1 Point) May 28, 2010 at 10:46 pm

    wow, amazing. thanks for sharing.

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  26. Add point Subtract point
    mohammad (1 Point) May 27, 2010 at 7:54 am

    great great tutorial ,thanks alot

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  27. Add point Subtract point
    Rodrigo (1 Point) May 19, 2010 at 11:16 pm

    Nice information about the Photoshop curve, amazing!
    Congrats for the autor!

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  28. Add point Subtract point
    aditya mani (1 Point) May 14, 2010 at 6:30 am

    hey thanks a lot…..cudnt make head r tail of those curves b4 this

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  29. Add point Subtract point
    meline (1 Point) May 13, 2010 at 11:54 am

    Thanks for taking time and sharing your knowlage,we need your tuts,

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  30. Add point Subtract point
    Anthony Pittarelli (1 Point) May 11, 2010 at 4:01 am

    Perfect! Ive been looking for this exact article for a long time! Thanks for taking the time to do it!

    Anthony Pittarelli

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  31. Add point Subtract point
    Kyle Lucas (1 Point) May 10, 2010 at 10:09 am

    i work largely in Adobe After Effects, and i always fiddled with curves, but now it makes sense! Thanks

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  32. Add point Subtract point
    imtiaz jenin (1 Point) May 4, 2010 at 2:36 pm

    thanks for this advise

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  33. Add point Subtract point
    Web Design (1 Point) April 26, 2010 at 7:54 pm

    Awesome tutorial! thanks for sharing

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  34. Add point Subtract point
    David Hardwick Photography (1 Point) April 23, 2010 at 3:17 pm

    This is a very helpful article. Thanks for publishing and making curves a lot easier to understand.

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  35. Add point Subtract point

    Nice tutorial, really useful for tweaking photos.

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  36. Add point Subtract point

    Oh thank you a site that has explantions i can understand on photo shop!
    woooohooo!

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  37. Add point Subtract point

    Nice explanation of curves. I learned some good information! Much appreciated!

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  38. Add point Subtract point

    Owen, I just wanted to say that I really enjoy your direct and understandable way of writing/teaching. :)

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  39. Add point Subtract point
    aryani_muslimah (1 Point) April 7, 2010 at 9:32 pm

    fantastic…i will fun to learn…thanks

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  40. Add point Subtract point
    Peter Stanis (1 Point) April 5, 2010 at 7:00 pm

    Simple and to the point. Nice job.

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  41. Add point Subtract point
    dpersson (1 Point) March 30, 2010 at 4:33 am

    Pedagogic 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.

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  42. Add point Subtract point
    Edgard (1 Point) March 29, 2010 at 7:01 am

    Great and easy steps! TK!
    So simple,so important!
    Tk,Tk, Tk!

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  43. Add point Subtract point
    Janis Gloystein (1 Point) March 27, 2010 at 6:20 pm

    Hi there and thanks for the great article.
    What 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

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  44. Add point Subtract point
    elisabetta serafini (1 Point) March 27, 2010 at 8:49 am

    I will like to try… i am a beginner… as many
    Thanks

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  45. Add point Subtract point
    Francois (1 Point) March 27, 2010 at 4:02 am

    Thanks for demistifying the curves app for me

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  46. Add point Subtract point
    刘苏 (1 Point) March 27, 2010 at 3:20 am

    刘苏到访,留个脚印…

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  47. Add point Subtract point
    Charles D.MII (1 Point) March 26, 2010 at 7:59 pm

    this has been great help Thanks Man!!!

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  48. Add point Subtract point
    Charles D.MII (1 Point) March 26, 2010 at 7:55 pm

    great information im currently looking for help and this has been more useful than i could imagine.
    Thanks alot!!!

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  49. Add point Subtract point
    Elizabeth (1 Point) March 26, 2010 at 6:38 pm

    I’m a beginner. Everything is useful.

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  50. Add point Subtract point

    Always shy away from using levels, but will attempt to use them now. Thank you Owen, great tutorial!

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  51. Add point Subtract point
    countocram (1 Point) March 26, 2010 at 12:14 pm

    very informative, thank you for sharing this! I’ve been using Curves on Post Processing, this is very helpful!

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  52. Add point Subtract point
    Sit Kong Sang (1 Point) March 26, 2010 at 12:08 pm

    Very 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.

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  53. Add point Subtract point

    Very nice and good tutorial for beginners.

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  54. Add point Subtract point

    I use curves all the time…the simple s-curve can make all the difference.

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  55. Add point Subtract point

    Good tutorial, there is so much more to photoshop than I commonly use.

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  56. Add point Subtract point

    Finaly I know how to use curves… thank you :D

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  57. Add point Subtract point
    Yasmin Lawsuit (1 Point) March 17, 2010 at 2:12 pm

    Very useful for beginning photoshoppers!

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  58. Add point Subtract point
    Daniel (1 Point) March 15, 2010 at 1:14 pm

    Thank you. I used this technique in my blog.. Thanks a lot…

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  59. Add point Subtract point
    Nimit Kashyap (1 Point) March 12, 2010 at 1:29 am

    very useful post, helped me alot

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  60. Add point Subtract point
    WebGuide4U (2 Points) March 11, 2010 at 7:30 pm

    i 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.

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  61. Add point Subtract point
    Rondell Paul (1 Point) March 11, 2010 at 1:27 pm

    very nice post indeed….i didn’t know Curves could do so much!

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  62. Add point Subtract point
    Tidy Design (1 Point) March 11, 2010 at 10:30 am

    Very nice post, we are loving CS4 at Tidy Design… Keep these great tutorials coming! :D

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  63. Add point Subtract point
    Jose Gonzalez (1 Point) March 11, 2010 at 9:50 am

    This is an awesome post!!!!

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  64. Add point Subtract point

    Really great handling of examples!

    I could instantly appreciate the purpose of curves in photoshop. :D

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  65. Add point Subtract point
    Lava360 (1 Point) March 11, 2010 at 4:49 am

    tell you the truth. these curves are difficult to handle. for me at least. thanks for these great tips

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  66. Add point Subtract point

    Simple yet important topic explained.. Wow

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  67. Add point Subtract point
    Photoshop Magic Wand Tool (2 Points) March 10, 2010 at 12:59 pm

    one of the best tutorials on such topics
    thanks very much

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  68. Add point Subtract point
    Dim Geo (1 Point) March 10, 2010 at 12:36 pm

    Well written tutorial. Thank you!

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  69. Add point Subtract point

    great tutorial.

    i like it.

    thanks

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  70. Add point Subtract point
    Valerie Morgan (1 Point) March 10, 2010 at 10:14 am

    Thanks for the tutorial! I had always just blindly adjusted them hoping for the desired result or avoided using them altogether.

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  71. Add point Subtract point
    nurbie (1 Point) March 10, 2010 at 10:10 am

    Thanks for the tut! I got in to curves via trial and error, this really explained the why for me :) Thanks!

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  72. Add point Subtract point

    Great tutorial, I like many others wasn’t overly sure how it all worked, so this is great for me.

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  73. Add point Subtract point
    Steve Mullen (1 Point) March 10, 2010 at 9:47 am

    Thanks 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.

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  74. Add point Subtract point
    Semi_Deus (1 Point) March 10, 2010 at 8:58 am

    Great 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.

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  75. Add point Subtract point
    Ubiratan (1 Point) March 10, 2010 at 8:03 am

    Simply fantastic and easy to understand. Thanks a lot!

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  76. Add point Subtract point
    Dan O’Neill (1 Point) March 10, 2010 at 4:26 am

    Never used curves before, but I can see it having a huge benefit to some of my pictures.

    Thanks for this, tutorial9!

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  77. Add point Subtract point
    Jordy666sic (1 Point) March 10, 2010 at 3:33 am

    I 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!
    Thank you very much :)

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  78. Add point Subtract point
    DesignTutr (1 Point) March 10, 2010 at 2:00 am

    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!

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  79. Add point Subtract point
    Erik Ford (1 Point) March 10, 2010 at 12:25 am

    Thanks for the tutorial. There are a couple of methods here I was not aware of and will definitely be using.

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  80. Add point Subtract point
    Ben Bray (1 Point) March 9, 2010 at 8:39 pm

    The rollovers aren’t working for me. I use Google Chrome.

    Other than that, great tutorial!

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  81. Add point Subtract point
    frank elejalde (1 Point) March 9, 2010 at 8:17 pm

    Very 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!

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  82. Add point Subtract point
    jurgen (1 Point) March 9, 2010 at 3:45 pm

    I think this is one of the best tutorials/articles on Tutorial9! Also the best explanation of curves I’ve seen so far. Really great!

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  83. Add point Subtract point
    David (1 Point) March 9, 2010 at 3:19 pm

    Good stuff. I’ll be back

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  84. Add point Subtract point

    Well done on this tutorial. You have made curves very simple to understand.

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  85. Add point Subtract point
    Artboy34 (1 Point) March 9, 2010 at 2:21 pm

    I 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!

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  86. Add point Subtract point
    Kevin Barney (1 Point) March 9, 2010 at 1:29 pm

    I’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. =)

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  87. Add point Subtract point
    Amberly | Web Designer (1 Point) March 9, 2010 at 12:02 pm

    Interesting Tut. Thanks for this well explained tutorial.

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  88. Add point Subtract point

    Very well written tutorial. Thanks

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  89. Add point Subtract point

    This is the best explanation of curves I’ve ever read. Thanks!!

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  90. Add point Subtract point
    psn card (0 Points) March 9, 2010 at 9:46 am

    PlayStation Network Cards or psn cards are prepaid cards used to buy PlayStation 3 and PlayStation Portable contents in the online PlayStation network. Our Online PSN Store is easy to buy psn card USA only) directly via Paypal which is very safe.

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  91. Add point Subtract point

    Great tutorial, learned a lot here

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