How to extract Coordinates from Video/Image Input?

Short abstract on the Project: Projecting a swarm of fish on the ground (with a projector) and when someone walks through the projection, the fish swim AROUND the person.

Setup, projector looking straight at the ground, IR Camera next to it.

The plan is to get a Video Input (Webcam, NDI, etc) and isolate a specific feature. This specific feature would be an infrared LED in this specific case. Via Blueprints, I´m going to put all Color Values to 0 except for the brightest part of the image (The Infrared LED), which is 1.

Now the question is: How do I figure out the correct coordinates from this Black White Source, given that the aspect ratio and PixelSize of Output/Input are the same? 1920x1080