Posterize--AE

This effect specifies the number of tonal levels (or brightness values) for each channel in an image and maps pixels to the closest matching level. For example, if you choose two tonal levels in an RGB image, you get two tones for red, two tones for green, and two tones for blue. Values range from 2 to 255. Although the results of this effect are most evident when you reduce the number of gray levels in a grayscale image, Posterize also produces interesting effects in color images.

Use Level to adjust the number of tonal levels for each channel to which Posterize will map existing colors.

Applying Effects > Video effects included with Premiere > Posterize--AE