354 The Digital Filmmaking Handbook, 4E

RGB color balance filters like the one shown in Figure 16.5 give you control over the Red, Green, and Blue channels of the video signal. They work on a sliding scale, and if you decrease the blue, you will increase its opposite color, yellow. Decreasing the red will increase the cyan, and decreasing the green will increase the magenta.

And last, but not least, remember that enhancing skin tones is one of the primary concerns when manipulating the color of your film. It might look amazing to have the sky turn bright green but not if it renders your actress’ skin blue. If you are unsure about your color correction choices, keeping an eye on the skin tones of your cast is the easiest way to feel confident that you aren’t going too far.

Save Your Presets

As you work with color correction filters, save the ones you like along the way. You may find that you can use them to correct a number of shots.

Too Much of a Good Thing

If you’ve been trying out the color correction filters in your editing app, you’ve probably noticed that it doesn’t take much to make a wildly dramatic change to the look of your image. It might be fun to look at, but it’s rare that you are going to use such extremes in your final product. It’s important to recognize that it is possible to apply too much color correction.

Here’s what happens when you go overboard with color correction filters.

A digital image is composed of numbers that represent the color of each pixel. Color-correction tools simply manipulate these numbers using complex transformations. Unfortunately, a digital image has a finite amount of color data in it. You can manipulate this information, but eventually you’ll find that there simply isn’t enough data to take a correction as far as you might like. At this point, you’ll introduce artifacts and aberrations into your image.

When you apply color correction operations to a digital image, the computer will often have to discard image data. The result of these operations will be the same: with less image data, some tones in your image will posterize, resulting in areas of flat color in your picture. These artifacts probably won’t be as dramatic as our example, but they’ll still be there, and they can be very noticeable, particularly in the darker, shadowy areas of your image (see Figure 16.10).

Also, sometimes these artifacts are not that noticeable when you are only looking at a single frame, but when you play back your video at full motion, they can be very noticeable.

Choosing what type of correction to make is a subjective, aesthetic choice. Knowing when you’ve corrected too far, though, is a technical skill that separates good correction from bad. In the following examples, practice looking for posterization and reduction of tones as you perform your corrections. This is a habit that you will need to develop for all of your personal correction chores.