<s>
The	O
Kirsch	B-Algorithm
operator	I-Algorithm
or	O
Kirsch	O
compass	O
kernel	O
is	O
a	O
non-linear	O
edge	B-Algorithm
detector	I-Algorithm
that	O
finds	O
the	O
maximum	O
edge	O
strength	O
in	O
a	O
few	O
predetermined	O
directions	O
.	O
</s>
<s>
The	O
edge	O
magnitude	O
of	O
the	O
Kirsch	B-Algorithm
operator	I-Algorithm
is	O
calculated	O
as	O
the	O
maximum	O
magnitude	O
across	O
all	O
directions	O
:	O
</s>
