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:
The following are the other sections of this module:
Color Balance and White Balance - An introduction to this module. Covering the basics of these two concepts, including a basic explanation of color and light.
- Using the Color Balance Tool - A nice tool for correcting global color casts. This is not as powerful as using levels when it comes to White Balance, but is better for color adjusting specific tonal ranges (shadows, midtones, highlights).
- Using Levels to Correct White Balance - how to powerfully correct for white balance as well as fine-tuned color balance.
- Using Hue/Saturation for Color Control - Basics - Covers what This tool can do generally.
- Using Hue/Saturation for Color Control - Advanced - A highly under-used tool for how powerful it can be in doing selective color adjustment that by-passes the crossover problem!
- Replacing Color - The final word in color adjustment! When all else fails to work, and crossover seems unbeatable, this tool takes the cake. The only drawback is that it isn't available as a layer.
- Painting Color Casts The ultimate way to change a color! This technique will become your best friend. It allows tou to change color casts in specific locations and to precise degrees.