The random expression in After Effects is powerful. It can be used for many things, one of which is randomly changing the color value. This saves a ton of keyframing work if you’re looking to generate random values. To do this, we use the expression:
To define the two variables for color being used as the arguments in the expression, we must use an array. Color has four values: R, G, B and A. A is alpha, which is not really important in this example. So, we set the variable for the minimum value to an array that is all zeros, and we set the variable for the maximum value to an array that is all ones. This will cover all possible colors.
To slow down the animation, you can use the posterizeTime() expression and place the number of fps in the parenthesis. For example, putting 5 in parenthesis will make the color change five times per second in your composition.
If you do not want to have all the potential colors appear, you can use color controls to set the beginning and ending colors. Then, the animation will choose random color values that are between those colors.
Check out this short tutorial video to see the random color expression in action: