B = 
The problem here is to overlay a binary annotation image over a grey-level image. In most of the cases, the Maximum or Minimum operators works well, see further examples at the end of this page. But there are cases where a simple Maximum or Minimum is not appropriate:
A =
B =
MAX(A,B)=
Using the maximum of both will not display the number 16 since both use pixel level 255.
A XOR B =
Using the bitwise Exclusive-Or operation will not display the number 8 since both use pixel level 128 (7FH XOR FF = 80H).
We need to create a Gating operator, i.e.
C = (A + 128) mod 256
The Gating operator combines A and B using C as a selector:
If (B) then C else A =
