Bair Art Edition's Tutorial on:
Adjusting Color & Exposure
In Adobe Photoshop

Color Adjustment: Color Balance Using Curves

Using curves to obtain color balance is analogous to using the levels tool - in that it is best for global color shifts because it compresses/stretches the tonal values across the image. In other words, it achevies an over-all shift in the shadows, midtones, and highlights. For color correction in a secific tonal range you can use the Color Balance tool.

As in other tools used for Color Balance, you must understand the relationship between the additive and subtractive color schemes. For Example, subtracting Red will result in more Cyan (it will actually result in the residual Green and Blue showing through more than it was, and Blue and Green make Cyan).

Once you've determined what color is either in excess or in want, go to the appropriate channel.

In this example, I will be warming up this image.

I want a little more Yellow and Magenta, or in other words, a little less Blue and Green! I first went to the green channel, and "pulled it down," This is telling the program that this value of Green, which was originally given a value of 127, should now be taken down to 122.

Next I went to the Blue channel, I landed my curser on value 130, and I brought it down to 123. Basically this not only decreases this value, it also "bends" the rest of the values. This is why it is called "curves." In the curve, where the anchor point is located has the greatest change, and that change "curves" or tapers off in intensity until you get to pure white and black (or in the case of the Blue channel, pure blue and no blue, respectively). At pure white (pure blue) the curve meets no bend, so you don't lose that value. the same thing happens at pure black (no blue contribution).

The result is a warmer image:

After Curves

The following are the other sections of this module: