Tutorial: Color Isolation in After Effects
Posted May 1, 2008

Not long ago, I read Lance Gray’s tutorial on isolating a color using Photoshop. Lance’s tutorial focused on color isolation in still images. You can also achieve this effect on the video side of things, and for that, the perfect application is After Effects—which is, after all, Photoshop on a timeline. This tutorial will help you to achieve the color isolation effect in your videos.There are several different ways in which we could tackle this task; this is just one of them.

Step 1: Import Your Video and Create a New Compositon
To begin, open After Effects and import the video. To do so, select Choose File > Import > File or use the shortcut Ctrl + i (for Windows users) or Cmd + i (for Mac users).

Next, create a composition for the clip by selecting Composition > New Composition (Figure 1, below) or by using the shortcut Ctrl/Cmd + n. Make sure your composition settings agree with the frame size, frame rate, and other properties of your source clip. You can also create a new composition by dragging the source clip to the New Composition icon, located in the bottom of the Project Panel.


figure 1

Step 2: Apply the Leave Color Effect
Once you have the clip in the Composition, you are ready to apply the effect. The effect that we will try is the Leave Color effect.

Apply this effect by selecting the clip (just click on it to select), and then go to Effect > Color Correction > Leave Color (Figure 2, below).

figure 1

Step 3: Choose a Color to Isolate
As soon as you apply the effect, you will notice that the Effect Controls panel becomes visible (if it doesn’t, select Window > Effect Controls). In the Effect Controls panel, do the following:

  1. Click on the eyedropper and then click on the color that you would like to isolate.
  2. Change the Amount to Decolor to 100%.
  3. Change the values for Tolerance and Edge Softness until you get the desired look on your video.

If you do not get the desired effect, try changing the Match colors settings to Using Hue instead of Using RGB (Figure 3, below), then re-adjust the values of the effect. In many cases, this is all you will need to do to achieve this effect.

figure 1

Step 4: Get Rid of an Unwanted Color
There are occasions in which this effect will not work to your expectations. There might be similar colors in other parts of the image that did not turn grayscale with the effect. If this is the case, you need to take a few additional steps. Begin by duplicating the layer. Select the layer and choose Edit> Duplicate or use the shortcut Ctrl/Cmd + d. You should now have two layers in your composition.

Select the bottom layer and delete the effect from the Effect Controls Panel by clicking on the effect and then pressing Delete on your keyboard. With the bottom layer still selected, choose Effect > Color Correction > Hue/Saturation.

Right after you apply this effect, locate the Effect Controls panel. Choose the Master Saturation values of the effect and lower its value to 0 (Figure 4, below). This will turn your lower layer into a grayscale video and you’ll be able to use this to get rid of the unwanted color that still exists on your top layer.

figure 1

Step 5: Create a Moving Mask
The best way to "cut a hole" on the top layer is by creating a mask. Because this is a moving video, this will have to be a moving mask.
Click on the top layer and choose the Pen Tool. Next, select RotoBezier from the Pen Tool options. Create a loose selection around the color that you would like to isolate. With that layer still selected, press the letter m. Then choose the Selection Tool from the tools panels (or press the letter v). You should not be using the Pen Tool anymore.

Next, keyframe the Mask Path. Then move the CTI (Edit line) to the end of the composition and move the individual points so that the color that you would like to isolate is still inside the mask.

To move the individual vertex points, open the Composition Panel (Monitor). Use the selection tool and deselect the mask by clicking somewhere outside of it. Select the desired vertex point and move it.

You will notice that just the fact that you moved that one vertex point created a new keyframe in the Timeline. Move the other vertex points until the mask is where it needs to be (Figure 5, below).

figure 1

Next, move the CTI left toward the beginning of thecomposition and move the vertex points of the maskagain (this will create a new keyframe). Do the same toward the end until you have keyframed the entire clip.

Note: If your clip is 10 seconds long, keyframe in this order: