Percentage of black calulator utility

You can't see how much of doc is white because it's on white background on this forum. But I trust you get my meaning

So I'm trying to determine how much of the space as a percentage of a pure white document is used by the pure black circle I added. I was not concerned about the intensity. Are you saying the intensity has something to do with figuring that out?

Thanks, Sphinxmorpher

Inside or outside the filter is fine I just needed visual access to the figure without having to do the math formula of determining the surface area of the black and deducting that from the surface area of the whole doc to get the percentage of black surface area involved in the document.

Such a math formula could get pretty tricky on(let's say)a black and white reaction-diffusion image.

So this will work for me I think what you've done here yielding the 24.6% equivalent figure provides me with a way to have the number I'm after on any image.

The purpose of the number is to tell me when a complex black and white pattern has a surface area that is 50 percent black and therefore 50 percent white (aka balanced)
rather than just eyeballing it.
Thanks Much