Hasta La Motion!

So I want to analyze an entire image to find the minimum energy of all the pixels in an image. I am aware you can use the CurveTool node and the MaxLuma operation to do this, however this is not a dynamic or per frame relationship. It is something that needs baking each time the source image changes. Normally this would be fine, but I would like something that updates without re-baking.

In Shake there is a node called Stat which finds the min, max or average energy of an image and is processed each frame, ie no pre-baking. One can use this to return a given value and utilize it for flashing, or dynamically matching black levels.

So my question is this. Does anyone know the image analysis math to process an entire image for the minimum (or max) pixel value? I imagine it involves scanning each x and y row of pixels and comparing them to return the lowest/highest/average value.

Hope that explains what I need. Now hit me math dorks.