The basic principle behind color correction is adjusting Highlight, Midtone and Shadow across Red, Green and Blue channels of your digital images or movies. You can fix imbalances in lighting by regulating the bright, medium and white levels of each individual clip in your project.

There are three different methods of color correction: adjusting gray scale levels (Levels); working with Hue, Saturation and Lightness (HSL) wheel; or editing Curves.

Color Correcting with Levels:

1. In the Timeline, select a clip on which the filter will be applied.
2. Click Clip: Video Filters.
3. In the Video filters dialog box, select Color Correction from Available filters to the left. Click Add>> then click Options.
4. In the Color Correction dialog box, click the Levels tab. Click the Master button to select all pixels across the tonal range for adjustment as opposed to selecting only bright (Highlights), medium tone (Midtones) and dark (Shadow) pixels.
5. Adjust the horizontal Input tonal values with either leftmost black point slider, rightmost white point slider or the middle grayscale slider. If you rather wish to reduce the overall tone, consider shifting the black and white threshold limits with the vertical Output tonal slider. Preview the difference.
6. To adjust Highlights, Midtones and Shadows separately, click on each corresponding button to the left of the Levels graph.
   
   Tip: To speed things up, use the three eyedropper tools. Black eyedropper is used to remap selected bright values towards darker black tones. Gray eyedropper will neutralize the clicked areas while the white eyedropper will remap selected pixels to brighter values.

Color Correcting with the HSL wheel:

As an alternative to the Levels, you might find it more suitable to color correct by adjusting the Hue (color), Saturation (amount of color) and Luminance (brightness). You can either use slider controls or the HSL color wheel to remap the values.

Either drag the black horizontal ruler on the wheel or use the slider to adjust the saturation first then click-drag on the outer circle of the wheel to select the color.

• Hue shift changes the color in a linear fashion sliding through the spectrum.
• Gamma determines the total number of colors.
• Gain multiplies your pixels with a higher (brighter) value, boosting the colors.
• Saturation sets the intensity of the color.
• Contrast sets the amount of contrast.
• Luminance alters the overall brightness.

Color Correcting with Curves:

Editing curves is the most straight-forward approach. It allows you to directly remap the tonal values in the video or any channel of the video. The most important thing to remember while working on the curves is the X and Y axis relation. The horizontal axis represents current values of the pixels in the video from 1 to 256. The vertical axis represents tonal values in the video.

1. In the Color Correction Tool dialog box, click Curves to access the controls.
2. Click on one of the color channels button to select a particular channel for color correction, or click the Master button to color correct all three RGB channels.
3. Draw a curve in the curve window.