<s>
In	O
signal	O
processing	O
,	O
a	O
filter	O
's	O
frequency	O
response	O
comprises	O
regions	O
of	O
frequency	O
called	O
passbands	B-Algorithm
,	O
stopbands	O
,	O
and	O
transition	O
regions	O
.	O
</s>
<s>
A	O
transition	O
region	O
(	O
or	O
transition	B-Algorithm
band	I-Algorithm
)	O
is	O
the	O
interval	O
between	O
a	O
passband	B-Algorithm
and	O
a	O
stopband	O
,	O
where	O
the	O
curve	O
of	O
amplitude	O
vs	O
frequency	O
continuously	O
changes	O
between	O
a	O
high	O
level	O
and	O
a	O
low	O
level	O
.	O
</s>
