Calculate Average Brightness of a Texture (Still or Video)

Oh, hey there,
there is a screen in my scene and I want to simulate its light emission into the scene.
Like a TV screen brightens the room.

So, my thought is:
Calculate the average brightness of a texture / current frame of a avideo texture
and set a lights brightness to that value.

It wouldn’t be perfect, however, it would suit my needs.

Can anyone point me in a direction, where I could find a solution for this?

I dont know is it good solution to use lightProbe that placed into box with parameter side:THREE.backSide and map:video.mp4. And need to use renderer with small resolution for speed calculation. lightProbe give 9 values of light, but maybe we need only first 3 values to put them to pointLight.