Mar 12, 2012

All About Curves. From Colors to Adjusting Shadows and Highlights

Using Curves to Adjust Colors

Curves basically allow you to change the information on your histogram, altering how an image looks. When used simply, you can make an image brighter or darker, or add some color.

Today we are going into a little more depth with curves, showing how to adjust highlights and shadows separately and how to use the different color channels!

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user image You
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  • user image

    hi aron can you show us how to have make a action for copy and paste
    thank you

  • user image
    David Platt

    Especially with caucasian skin, it helps to use the eye dropper tool and set a point by holding shift while clicking in a neutral skin area and basing your adjustments off of that. That will then show the original and changed RGB values in the info panel.

    What I do is use a little trick with the technique I mentioned above. After setting a reference point, change the color mode of the point to CMYK, and then you want to use the curves adjustments to make the Cyan be ~ 1/3 of the Magenta value, and the Yellow value to be just a little bit higher than the Magenta.

    For example, an image I worked on earlier had a nice skin tone with 18C, 51M, and 53Y. You can change each of these values by using the curves adjustment and the hand tool with the R, G, and B curves like Aaron showed above.

    The formula (C is 1/3 of M, M is a little less than Y) can be changed depending on the darkness of the skin you’re working with.

    • user image
      Daniel Thom

      I do something very similar when I forget to shoot a gray card or otherwise don’t feel like the colors are quite right (light changed, swapped modifiers, etc).  It’s *really* fast to make the adjustments based on value and will definitely get you very close to where you want to be.  I set a sample point with a wide radius just outside of a highlight area on the forehead (since it should be pretty neutral in terms of skin tones unlike cheeks for example which have more red).

      After I’m all done with this and get things adjusted to be “correct by color”, then I go ahead and do any other editing and retoning and screw the colors all back up again:->  At least I know what the baseline “correct” image looked like…