<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
is	O
a	O
generalized	O
technique	O
for	O
signal	O
and	O
image	B-Algorithm
processing	I-Algorithm
,	O
involving	O
a	O
nonlinear	O
mapping	O
to	O
a	O
different	O
domain	O
in	O
which	O
linear	O
filter	O
techniques	O
are	O
applied	O
,	O
followed	O
by	O
mapping	O
back	O
to	O
the	O
original	O
domain	O
.	O
</s>
<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
is	O
sometimes	O
used	O
for	O
image	B-Application
enhancement	I-Application
.	O
</s>
<s>
Here	O
homomorphic	B-Algorithm
filtering	I-Algorithm
is	O
used	O
to	O
remove	O
multiplicative	B-Algorithm
noise	I-Algorithm
.	O
</s>
<s>
Illumination	O
variations	O
can	O
be	O
thought	O
of	O
as	O
a	O
multiplicative	B-Algorithm
noise	I-Algorithm
,	O
and	O
can	O
be	O
reduced	O
by	O
filtering	O
in	O
the	O
log	O
domain	O
.	O
</s>
<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
can	O
be	O
used	O
for	O
improving	O
the	O
appearance	O
of	O
a	O
grayscale	O
image	O
by	O
simultaneous	O
intensity	O
range	O
compression	O
(	O
illumination	O
)	O
and	O
contrast	O
enhancement	O
(	O
reflection	O
)	O
.	O
</s>
<s>
According	O
to	O
figures	O
one	O
to	O
four	O
,	O
we	O
can	O
see	O
how	O
homomorphic	B-Algorithm
filtering	I-Algorithm
is	O
used	O
for	O
correcting	O
non-uniform	O
illumination	O
in	O
the	O
image	O
,	O
and	O
the	O
image	O
become	O
clearer	O
than	O
the	O
original	O
.	O
</s>
<s>
Thus	O
homomorphic	B-Algorithm
filtering	I-Algorithm
happens	O
accidentally	O
(	O
unintentionally	O
)	O
whenever	O
we	O
process	O
pixel	O
values	O
f(q )	O
on	O
the	O
true	O
quantigraphic	O
unit	O
of	O
light	O
q	O
.	O
</s>
<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
is	O
used	O
in	O
the	O
log-spectral	O
domain	O
to	O
separate	O
filter	O
effects	O
from	O
excitation	O
effects	O
,	O
for	O
example	O
in	O
the	O
computation	O
of	O
the	O
cepstrum	B-Algorithm
as	O
a	O
sound	O
representation	O
;	O
enhancements	O
in	O
the	O
log	O
spectral	O
domain	O
can	O
improve	O
sound	O
intelligibility	O
,	O
for	O
example	O
in	O
hearing	O
aids	O
.	O
</s>
<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
has	O
been	O
used	O
to	O
remove	O
the	O
effect	O
of	O
the	O
stochastic	O
impulse	O
train	O
,	O
which	O
originates	O
the	O
sEMG	O
signal	O
,	O
from	O
the	O
power	O
spectrum	O
of	O
the	O
sEMG	O
signal	O
itself	O
.	O
</s>
<s>
Homomorphic	B-Algorithm
filtering	I-Algorithm
was	O
used	O
in	O
this	O
latter	O
case	O
to	O
obtain	O
ISI	O
variations	O
from	O
the	O
power	O
spectrum	O
of	O
the	O
spike	O
train	O
in	O
output	O
from	O
a	O
neuron	O
with	O
or	O
without	O
the	O
use	O
of	O
neuronal	O
spontaneous	O
activity	O
.	O
</s>
<s>
The	O
frequency	O
of	O
the	O
sinusoidal	O
signal	O
was	O
recovered	O
by	O
using	O
homomorphic	B-Algorithm
filtering	I-Algorithm
based	O
procedures	O
.	O
</s>
