[Feature request] masked MinMaxDifference

[Purfview]

Would it be possible to do masked MinMaxDifference where black area from a mask is omitted?
That would allow to get stats from only the relevant parts of the frames.

[pinterf]

I suppose it should work in general for all min/max/median/... functions. Thresholded modes (median as well, which is an 50% threshold) however calculate with with total pixel count.

Question: if - special case - mask is all black, then the total pixel count is zero. This would affect average as well.
What is the required action for this? Report an error?

Question2: the full opacity (255 in 8-bits) can also have special meaning. Does your proposal have a reason to use 0-black for the purpose? (I don't mind, just asking, I don't know the actual use case)

[Purfview]

In my use cases I check that a mask is present and is not full opacity before doing anything. So I don't have use for both special cases.

Btw, later I found that there is RT_YPlaneMinMaxDifference in RT_Stats plugin.
It's doing -> "Return int -1, if no valid pixels in Mask clip."