To Color-Correct:

This procedure is similar to Levels:

1. Click on the Drop-Down Menu, and pick the Color Channel you desire to add or subtract.

2. Use Points to correct your color: As an example, you want to add Yellow to offset a Blue bias to your image.  Pick the “Blue” Channel (the opposite of Yellow) from the Drop-Down Menu, add points at the desired location, then move your points below the baseline to correct.

Here’s another example of where Curves differ from Levels: Let’s say that you have a Blue bias in your “Shadows” area of your image that you want to correct--the rest of the image looks great.  With curves, you have the option of correcting the blue bias in the “Shadows” by moving a point down below the baseline in the shadows area only in your “Blue” Channel Curve.  To keep the rest of the curve from moving (midtones and highlights), simply set “anchor” points where needed.

Here are two “real-life” examples of how to use Curves, followed by commentary as to what was done and why….

This “tiger” example is a correction for Contrast only: The uncorrected image is dark and lacking in contrast; it needs some extra “snap”, which is reflected in the histogram superimposed behind the curve (almost no “light” pixels). 

The corrected image shows noticeable improvement in contrast and brightness.  This was accomplished by creating a simple “S” curve in the RGB Channel, with a little extra increase in brightness in the midtones.

This “plant” example below is a correction for Color only:
The uncorrected image needs to be warmed up--the color bias is too Blue/Cyan.

The corrected image looks like the sun is shining on it.  This is accomplished by adding Red and Yellow overall.

Until next month, Have Fun!!!