How to make this effect?

[Guest]

How to make one part of the frame brighter and the other part of the frame darker?

[Rick Gerard]

Add a mask, turn it off, add a color correction effect and have it use the mask. If you have no idea how to do that try searching the User Guide for "control effects with a mask."

There are about a hundred other methods I can think of so without more details and knowing your experience level with After Effects any further suggestions are pretty much a waste of time.

[DigitalSpatula]

You can easily create an adjustment layer above your image. Add a mask to the adjustment layer then add an effect to the adjustment layer. This will affect all pixels below the masked adjustment layer.

Steve

[Guest]

Which part is going to be brighter and which part of keyframe is darker? You mean make mask with brighter color and add the darker effect to adjustment layer?

[Rick Gerard]

This should not be that hard to understand. Here's a one-minute tutorial showing how to control an effect with a mask:

[DigitalSpatula]

You add your effect to the adjustment layer which applies the effect to all layers underneath it. Then add a mask to the adjustment layer to only apply the effect to the masked part of the frame.

Steve