<s>
Edge	B-Algorithm
enhancement	I-Algorithm
is	O
an	O
image	B-Algorithm
processing	I-Algorithm
filter	O
that	O
enhances	O
the	O
edge	O
contrast	O
of	O
an	O
image	O
or	O
video	O
in	O
an	O
attempt	O
to	O
improve	O
its	O
acutance	B-Algorithm
(	O
apparent	O
sharpness	O
)	O
.	O
</s>
<s>
This	O
has	O
the	O
effect	O
of	O
creating	O
subtle	O
bright	O
and	O
dark	O
highlights	O
on	O
either	O
side	O
of	O
any	O
edges	O
in	O
the	O
image	O
,	O
called	O
overshoot	B-Algorithm
and	O
undershoot	B-Algorithm
,	O
leading	O
the	O
edge	O
to	O
look	O
more	O
defined	O
when	O
viewed	O
from	O
a	O
typical	O
viewing	O
distance	O
.	O
</s>
<s>
A	O
modern	O
television	O
set	O
's	O
"	O
sharpness	O
"	O
control	O
is	O
an	O
example	O
of	O
edge	B-Algorithm
enhancement	I-Algorithm
.	O
</s>
<s>
Most	O
digital	B-Device
cameras	I-Device
also	O
perform	O
some	O
edge	B-Algorithm
enhancement	I-Algorithm
,	O
which	O
in	O
some	O
cases	O
cannot	O
be	O
adjusted	O
.	O
</s>
<s>
Edge	B-Algorithm
enhancement	I-Algorithm
can	O
be	O
either	O
an	O
analog	O
or	O
a	O
digital	O
process	O
.	O
</s>
<s>
Analog	O
edge	B-Algorithm
enhancement	I-Algorithm
may	O
be	O
used	O
,	O
for	O
example	O
,	O
in	O
all-analog	O
video	O
equipment	O
such	O
as	O
modern	O
CRT	O
televisions	O
.	O
</s>
<s>
Edge	B-Algorithm
enhancement	I-Algorithm
applied	O
to	O
an	O
image	O
can	O
vary	O
according	O
to	O
a	O
number	O
of	O
properties	O
;	O
the	O
most	O
common	O
algorithm	O
is	O
unsharp	B-Algorithm
masking	I-Algorithm
,	O
which	O
has	O
the	O
following	O
parameters	O
:	O
</s>
<s>
Where	O
available	O
,	O
this	O
adjusts	O
the	O
sensitivity	O
of	O
the	O
edge	B-Algorithm
detection	I-Algorithm
mechanism	O
.	O
</s>
<s>
In	O
some	O
cases	O
,	O
edge	B-Algorithm
enhancement	I-Algorithm
can	O
be	O
applied	O
in	O
the	O
horizontal	O
or	O
vertical	O
direction	O
only	O
,	O
or	O
to	O
both	O
directions	O
in	O
different	O
amounts	O
.	O
</s>
<s>
This	O
may	O
be	O
useful	O
,	O
for	O
example	O
,	O
when	O
applying	O
edge	B-Algorithm
enhancement	I-Algorithm
to	O
images	O
that	O
were	O
originally	O
sourced	O
from	O
analog	O
video	O
.	O
</s>
<s>
Unlike	O
some	O
forms	O
of	O
image	O
sharpening	O
,	O
edge	B-Algorithm
enhancement	I-Algorithm
does	O
not	O
enhance	O
subtle	O
detail	O
which	O
may	O
appear	O
in	O
more	O
uniform	O
areas	O
of	O
the	O
image	O
,	O
such	O
as	O
texture	O
or	O
grain	O
which	O
appears	O
in	O
flat	O
or	O
smooth	O
areas	O
of	O
the	O
image	O
.	O
</s>
<s>
As	O
with	O
other	O
forms	O
of	O
image	O
sharpening	O
,	O
edge	B-Algorithm
enhancement	I-Algorithm
is	O
only	O
capable	O
of	O
improving	O
the	O
perceived	O
sharpness	O
or	O
acutance	B-Algorithm
of	O
an	O
image	O
.	O
</s>
<s>
Further	O
sharpening	O
operations	O
on	O
the	O
resulting	O
image	O
compound	O
the	O
loss	O
of	O
detail	O
,	O
leading	O
to	O
artifacts	O
such	O
as	O
ringing	B-Algorithm
.	O
</s>
<s>
An	O
example	O
of	O
this	O
can	O
be	O
seen	O
when	O
an	O
image	O
that	O
has	O
already	O
had	O
edge	B-Algorithm
enhancement	I-Algorithm
applied	O
,	O
such	O
as	O
the	O
picture	O
on	O
a	O
DVD	O
video	O
,	O
has	O
further	O
edge	B-Algorithm
enhancement	I-Algorithm
applied	O
by	O
the	O
DVD	O
player	O
it	O
is	O
played	O
on	O
,	O
and	O
possibly	O
also	O
by	O
the	O
television	O
it	O
is	O
displayed	O
on	O
.	O
</s>
<s>
Essentially	O
,	O
the	O
first	O
edge	B-Algorithm
enhancement	I-Algorithm
filter	O
creates	O
new	O
edges	O
on	O
either	O
side	O
of	O
the	O
existing	O
edges	O
,	O
which	O
are	O
then	O
further	O
enhanced	O
.	O
</s>
<s>
The	O
ideal	O
amount	O
of	O
edge	B-Algorithm
enhancement	I-Algorithm
that	O
is	O
required	O
to	O
produce	O
a	O
pleasant	O
and	O
sharp-looking	O
image	O
,	O
without	O
losing	O
too	O
much	O
detail	O
,	O
varies	O
according	O
to	O
several	O
factors	O
.	O
</s>
<s>
An	O
image	O
that	O
is	O
to	O
be	O
viewed	O
from	O
a	O
nearer	O
distance	O
,	O
at	O
a	O
larger	O
display	O
size	O
,	O
on	O
a	O
medium	O
that	O
is	O
inherently	O
more	O
"	O
sharp	O
"	O
or	O
by	O
a	O
person	O
with	O
excellent	O
eyesight	O
will	O
typically	O
demand	O
a	O
finer	O
or	O
lesser	O
amount	O
of	O
edge	B-Algorithm
enhancement	I-Algorithm
than	O
an	O
image	O
that	O
is	O
to	O
be	O
shown	O
at	O
a	O
smaller	O
display	O
size	O
,	O
further	O
viewing	O
distance	O
,	O
on	O
a	O
medium	O
that	O
is	O
inherently	O
softer	O
or	O
by	O
a	O
person	O
with	O
poorer	O
eyesight	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
home	O
cinema	O
enthusiasts	O
who	O
invest	O
in	O
larger	O
,	O
higher	O
quality	O
screens	O
often	O
complain	O
about	O
the	O
amount	O
of	O
edge	B-Algorithm
enhancement	I-Algorithm
present	O
in	O
commercially	O
produced	O
DVD	O
videos	O
,	O
claiming	O
that	O
such	O
edge	B-Algorithm
enhancement	I-Algorithm
is	O
optimized	O
for	O
playback	O
on	O
smaller	O
,	O
poorer	O
quality	O
television	O
screens	O
,	O
but	O
the	O
loss	O
of	O
detail	O
as	O
a	O
result	O
of	O
the	O
edge	B-Algorithm
enhancement	I-Algorithm
is	O
much	O
more	O
noticeable	O
in	O
their	O
viewing	O
conditions	O
.	O
</s>
