TalkChess.com

[E Diaz]

From a human player point of view I'd take into account just the friendly pieces (black ones in this case) in order to evaluate the king security in the case of being near to a semiopen file.
Maybe counting white pieces as "semitransparent" in this kind of positions can be an approach worth to be tested.

PS: I'm assuming your question is for the general case, being this very position is a good example.
_________________
Two first meanings of the dutch word "leren":
1. leren [vc] (learn, larn, acquire) acquire or gain knowledge or skills.
2. leren [v] (teach, learn, instruct) impart skills or knowledge to.