Count TP, FP, FN, and TN at one half.
highlighted = computed this step
Count the positive outputs
At threshold 1/2, A is TP and B is FP, so TP=1 and FP=1.
TP=1,FP=1
Count the negative outputs
C is FN and D is TN, so FN=1 and TN=1.
FN=1,TN=1
The grid is exact
The confusion grid for threshold 1/2 is one count in each cell.
(TP,FP,FN,TN)=(1,1,1,1)