After satellite change detection, how can I score the extent of the change?

[sunhoro]

Hello all,

Is there a way to roughly score the extent of the change?
I need to somehow filter out the dataset that showed minimal change.

For example, I have a bunch of data sets for new construction detection.
Then after processing out the change detection, how can I automatically filter the locations that had new constructions?

[robmarkcole]

Typically the pixels that have changed are highlighted, so you can simply count them. The challenge is usually to identify meaningful change, e.g. floodwater, new construction.

[sunhoro]

I'm thinking of a process like removing small pixels, then computing white&black ratio.....
@robmarkcole do you know any simple ways to calculate black and white pixel ratio of an image?