Obtain information about one frame, like minimum x value of green pixels… (goal: automatically find overlay position)

[tobiasBora]

Thanks for this library. I’d like to automatically overlay two videos above a third image/video, say, in this example, in place of the colored elements:

To do that, I would need to find the maximum and minimum values of the x and y coordinate of all pixels whose colors are close to a given value (here green and blue), in order to obtain the appropriate position of the elements.

I can’t find how to proceed with this library, am I missing something?