<s>
Speckle	B-Algorithm
,	O
speckle	B-Algorithm
pattern	O
,	O
or	O
speckle	B-Algorithm
noise	I-Algorithm
is	O
a	O
granular	O
noise	B-Algorithm
texture	O
degrading	O
the	O
quality	B-Algorithm
as	O
a	O
consequence	O
of	O
interference	O
among	O
wavefronts	O
in	O
coherent	O
imaging	O
systems	O
,	O
such	O
as	O
radar	B-Application
,	O
synthetic	B-Application
aperture	I-Application
radar	I-Application
(	O
SAR	O
)	O
,	O
medical	B-Application
ultrasound	I-Application
and	O
optical	B-Application
coherence	I-Application
tomography	I-Application
.	O
</s>
<s>
Speckle	B-Algorithm
is	O
not	O
external	O
noise	B-Algorithm
;	O
rather	O
,	O
it	O
is	O
an	O
inherent	O
fluctuation	O
in	O
diffuse	O
reflections	O
,	O
because	O
the	O
scatterers	O
are	O
not	O
identical	O
for	O
each	O
cell	O
,	O
and	O
the	O
coherent	O
illumination	O
wave	O
is	O
highly	O
sensitive	O
to	O
small	O
variations	O
in	O
phase	O
changes	O
.	O
</s>
<s>
Although	O
scientists	O
have	O
investigated	O
this	O
phenomenon	O
since	O
the	O
time	O
of	O
Newton	O
,	O
speckles	B-Algorithm
have	O
come	O
into	O
prominence	O
since	O
the	O
invention	O
of	O
the	O
laser	O
.	O
</s>
<s>
Such	O
reflections	O
may	O
occur	O
on	O
materials	O
such	O
as	O
paper	O
,	O
white	O
paint	O
,	O
rough	O
surfaces	O
,	O
or	O
in	O
media	O
with	O
a	O
large	O
number	O
of	O
scattering	B-Algorithm
particles	I-Algorithm
in	O
space	O
,	O
such	O
as	O
airborne	O
dust	O
or	O
in	O
cloudy	O
liquids	O
.	O
</s>
<s>
Speckle	B-Algorithm
results	O
from	O
these	O
patterns	O
of	O
constructive	O
and	O
destructive	O
interference	O
shown	O
as	O
bright	O
and	O
dark	O
dots	O
in	O
the	O
image	O
.	O
</s>
<s>
Speckle	B-Algorithm
in	O
conventional	O
radar	B-Application
increases	O
the	O
mean	O
grey	O
level	O
of	O
a	O
local	O
area	O
.	O
</s>
<s>
Speckle	B-Algorithm
in	O
SAR	O
is	O
generally	O
serious	O
,	O
causing	O
difficulties	O
for	O
image	O
interpretation	O
.	O
</s>
<s>
In	O
SAR	O
oceanography	O
,	O
for	O
example	O
,	O
speckle	B-Algorithm
is	O
caused	O
by	O
signals	O
from	O
elementary	O
scatterers	O
,	O
the	O
gravity-capillary	O
ripples	O
,	O
and	O
manifests	O
as	O
a	O
pedestal	O
image	O
,	O
beneath	O
the	O
image	O
of	O
the	O
sea	O
waves	O
.	O
</s>
<s>
The	O
speckle	B-Algorithm
can	O
also	O
represent	O
some	O
useful	O
information	O
,	O
particularly	O
when	O
it	O
is	O
linked	O
to	O
the	O
laser	O
speckle	B-Algorithm
and	O
to	O
the	O
dynamic	O
speckle	B-Algorithm
phenomenon	O
,	O
where	O
the	O
changes	O
of	O
the	O
spatial	O
speckle	B-Algorithm
pattern	O
over	O
time	O
can	O
be	O
used	O
as	O
a	O
measurement	O
of	O
the	O
surface	O
's	O
activity	O
,	O
such	O
as	O
which	O
is	O
useful	O
for	O
measuring	O
displacement	O
fields	O
via	O
digital	O
image	O
correlation	O
.	O
</s>
<s>
The	O
speckle	B-Algorithm
effect	O
is	O
a	O
result	O
of	O
the	O
interference	O
of	O
many	O
waves	O
of	O
the	O
same	O
frequency	O
,	O
having	O
different	O
phases	O
and	O
amplitudes	O
,	O
which	O
add	O
together	O
to	O
give	O
a	O
resultant	O
wave	O
whose	O
amplitude	O
,	O
and	O
therefore	O
intensity	O
,	O
varies	O
randomly	O
.	O
</s>
<s>
If	O
light	O
of	O
low	O
coherence	O
(	O
i.e.	O
,	O
made	O
up	O
of	O
many	O
wavelengths	O
)	O
is	O
used	O
,	O
a	O
speckle	B-Algorithm
pattern	O
will	O
not	O
normally	O
be	O
observed	O
,	O
because	O
the	O
speckle	B-Algorithm
patterns	O
produced	O
by	O
individual	O
wavelengths	O
have	O
different	O
dimensions	O
and	O
will	O
normally	O
average	O
one	O
another	O
out	O
.	O
</s>
<s>
However	O
,	O
we	O
can	O
observe	O
speckle	B-Algorithm
patterns	O
in	O
polychromatic	O
light	O
in	O
some	O
conditions	O
.	O
</s>
<s>
a	O
laser	O
beam	O
)	O
is	O
imaged	O
,	O
a	O
speckle	B-Algorithm
pattern	O
is	O
observed	O
in	O
the	O
image	O
plane	O
;	O
this	O
is	O
called	O
a	O
"	O
subjective	O
speckle	B-Algorithm
pattern	O
"	O
–	O
see	O
image	O
above	O
.	O
</s>
<s>
It	O
is	O
called	O
"	O
subjective	O
"	O
because	O
the	O
detailed	O
structure	O
of	O
the	O
speckle	B-Algorithm
pattern	O
depends	O
on	O
the	O
viewing	O
system	O
parameters	O
;	O
for	O
instance	O
,	O
if	O
the	O
size	O
of	O
the	O
lens	O
aperture	O
changes	O
,	O
the	O
size	O
of	O
the	O
speckles	B-Algorithm
change	O
.	O
</s>
<s>
If	O
the	O
position	O
of	O
the	O
imaging	O
system	O
is	O
altered	O
,	O
the	O
pattern	O
will	O
gradually	O
change	O
and	O
will	O
eventually	O
be	O
unrelated	O
to	O
the	O
original	O
speckle	B-Algorithm
pattern	O
.	O
</s>
<s>
Thus	O
,	O
the	O
"	O
size	O
"	O
of	O
the	O
speckles	B-Algorithm
in	O
the	O
image	O
is	O
of	O
this	O
order	O
.	O
</s>
<s>
We	O
can	O
observe	O
the	O
change	O
in	O
speckle	B-Algorithm
size	O
with	O
lens	O
aperture	O
by	O
looking	O
at	O
a	O
laser	O
spot	O
on	O
a	O
wall	O
directly	O
,	O
and	O
then	O
through	O
a	O
very	O
small	O
hole	O
.	O
</s>
<s>
The	O
speckles	B-Algorithm
will	O
be	O
seen	O
to	O
increase	O
significantly	O
in	O
size	O
.	O
</s>
<s>
Also	O
,	O
the	O
speckle	B-Algorithm
pattern	O
itself	O
will	O
change	O
when	O
moving	O
the	O
position	O
of	O
the	O
eye	O
while	O
keeping	O
the	O
laser	O
pointer	O
steady	O
.	O
</s>
<s>
A	O
further	O
proof	O
that	O
the	O
speckle	B-Algorithm
pattern	O
is	O
formed	O
only	O
in	O
the	O
image	O
plane	O
(	O
in	O
the	O
specific	O
case	O
the	O
eye	O
's	O
retina	O
)	O
is	O
that	O
the	O
speckles	B-Algorithm
will	O
stay	O
visible	O
if	O
the	O
eye	O
's	O
focus	O
is	O
shifted	O
away	O
from	O
the	O
wall	O
(	O
this	O
is	O
different	O
for	O
an	O
objective	O
speckle	B-Algorithm
pattern	O
,	O
where	O
the	O
speckle	B-Algorithm
visibility	O
is	O
lost	O
under	O
defocusing	O
)	O
.	O
</s>
<s>
When	O
laser	O
light	O
which	O
has	O
been	O
scattered	O
off	O
a	O
rough	O
surface	O
falls	O
on	O
another	O
surface	O
,	O
it	O
forms	O
an	O
"	O
objective	O
speckle	B-Algorithm
pattern	O
"	O
.	O
</s>
<s>
If	O
a	O
photographic	O
plate	O
or	O
another	O
2-D	O
optical	O
sensor	O
is	O
located	O
within	O
the	O
scattered	O
light	O
field	O
without	O
a	O
lens	O
,	O
a	O
speckle	B-Algorithm
pattern	O
is	O
obtained	O
whose	O
characteristics	O
depend	O
on	O
the	O
geometry	O
of	O
the	O
system	O
and	O
the	O
wavelength	O
of	O
the	O
laser	O
.	O
</s>
<s>
The	O
speckle	B-Algorithm
pattern	O
in	O
the	O
figure	O
was	O
obtained	O
by	O
pointing	O
a	O
laser	O
beam	O
at	O
the	O
surface	O
of	O
a	O
mobile	O
phone	O
so	O
that	O
the	O
scattered	O
light	O
fell	O
onto	O
an	O
adjacent	O
wall	O
.	O
</s>
<s>
A	O
photograph	O
was	O
then	O
taken	O
of	O
the	O
speckle	B-Algorithm
pattern	O
formed	O
on	O
the	O
wall	O
.	O
</s>
<s>
Strictly	O
speaking	O
,	O
this	O
also	O
has	O
a	O
second	O
subjective	O
speckle	B-Algorithm
pattern	O
but	O
its	O
dimensions	O
are	O
much	O
smaller	O
than	O
the	O
objective	O
pattern	O
so	O
it	O
is	O
not	O
seen	O
in	O
the	O
image	O
.	O
</s>
<s>
Contributions	O
from	O
the	O
whole	O
of	O
the	O
scattering	O
surface	O
make	O
up	O
the	O
light	O
at	O
a	O
given	O
point	O
in	O
the	O
speckle	B-Algorithm
pattern	O
.	O
</s>
<s>
The	O
"	O
size	O
"	O
of	O
the	O
speckles	B-Algorithm
is	O
a	O
function	O
of	O
the	O
wavelength	O
of	O
the	O
light	O
,	O
the	O
size	O
of	O
the	O
laser	O
beam	O
which	O
illuminates	O
the	O
first	O
surface	O
,	O
and	O
the	O
distance	O
between	O
this	O
surface	O
and	O
the	O
surface	O
where	O
the	O
speckle	B-Algorithm
pattern	O
is	O
formed	O
.	O
</s>
<s>
Dainty	O
derives	O
an	O
expression	O
for	O
the	O
mean	O
speckle	B-Algorithm
size	O
as	O
λz/L	O
where	O
L	O
is	O
the	O
width	O
of	O
the	O
illuminated	O
area	O
and	O
z	O
is	O
the	O
distance	O
between	O
the	O
object	O
and	O
the	O
location	O
of	O
the	O
speckle	B-Algorithm
pattern	O
.	O
</s>
<s>
Objective	O
speckles	B-Algorithm
are	O
usually	O
obtained	O
in	O
the	O
far	B-Algorithm
field	I-Algorithm
(	O
also	O
called	O
Fraunhofer	B-Algorithm
region	I-Algorithm
,	O
that	O
is	O
the	O
zone	O
where	O
Fraunhofer	O
diffraction	O
happens	O
)	O
.	O
</s>
<s>
We	O
can	O
also	O
observe	O
speckles	B-Algorithm
close	O
to	O
the	O
scattering	O
object	O
,	O
in	O
the	O
near	O
field	O
(	O
also	O
called	O
Fresnel	O
region	O
,	O
that	O
is	O
,	O
the	O
region	O
where	O
Fresnel	O
diffraction	O
happens	O
)	O
.	O
</s>
<s>
We	O
call	O
this	O
kind	O
of	O
speckles	B-Algorithm
near-field	O
speckles	B-Algorithm
.	O
</s>
<s>
See	O
near	B-Algorithm
and	I-Algorithm
far	I-Algorithm
field	I-Algorithm
for	O
a	O
more	O
rigorous	O
definition	O
of	O
"	O
near	O
"	O
and	O
"	O
far	O
"	O
.	O
</s>
<s>
The	O
statistical	O
properties	O
of	O
a	O
far-field	B-Algorithm
speckle	B-Algorithm
pattern	O
(	O
i.e.	O
,	O
the	O
speckle	B-Algorithm
form	O
and	O
dimension	O
)	O
depend	O
on	O
the	O
form	O
and	O
dimension	O
of	O
the	O
region	O
hit	O
by	O
laser	O
light	O
.	O
</s>
<s>
By	O
contrast	O
,	O
a	O
very	O
interesting	O
feature	O
of	O
near	O
field	O
speckles	B-Algorithm
is	O
that	O
their	O
statistical	O
properties	O
are	O
closely	O
related	O
to	O
the	O
form	O
and	O
structure	O
of	O
the	O
scattering	O
object	O
:	O
objects	O
that	O
scatter	O
at	O
high	O
angles	O
generate	O
small	O
near	O
field	O
speckles	B-Algorithm
,	O
and	O
vice	O
versa	O
.	O
</s>
<s>
Under	O
Rayleigh	O
–	O
Gans	O
condition	O
,	O
in	O
particular	O
,	O
speckle	B-Algorithm
dimension	O
mirrors	O
the	O
average	O
dimension	O
of	O
the	O
scattering	O
objects	O
,	O
while	O
,	O
in	O
general	O
,	O
the	O
statistical	O
properties	O
of	O
near	O
field	O
speckles	B-Algorithm
generated	O
by	O
a	O
sample	O
depend	O
on	O
the	O
light	O
scattering	O
distribution	O
.	O
</s>
<s>
Actually	O
,	O
the	O
condition	O
under	O
which	O
the	O
near	O
field	O
speckles	B-Algorithm
appear	O
has	O
been	O
described	O
as	O
more	O
strict	O
than	O
the	O
usual	O
Fresnel	O
condition	O
.	O
</s>
<s>
When	O
lasers	O
were	O
first	O
invented	O
,	O
the	O
speckle	B-Algorithm
effect	O
was	O
considered	O
to	O
be	O
a	O
severe	O
drawback	O
in	O
using	O
lasers	O
to	O
illuminate	O
objects	O
,	O
particularly	O
in	O
holographic	B-Algorithm
imaging	O
because	O
of	O
the	O
grainy	O
image	O
produced	O
.	O
</s>
<s>
Researchers	O
later	O
realized	O
that	O
speckle	B-Algorithm
patterns	O
could	O
carry	O
information	O
about	O
the	O
object	O
's	O
surface	O
deformations	O
,	O
and	O
exploited	O
this	O
effect	O
in	O
holographic	B-Algorithm
interferometry	I-Algorithm
and	O
electronic	O
speckle	B-Algorithm
pattern	O
interferometry	O
.	O
</s>
<s>
Speckle	B-Algorithm
imaging	O
and	O
eye	O
testing	O
using	O
speckle	B-Algorithm
also	O
use	O
the	O
speckle	B-Algorithm
effect	O
.	O
</s>
<s>
Speckle	B-Algorithm
is	O
the	O
chief	O
limitation	O
of	O
coherent	O
lidar	O
and	O
coherent	O
imaging	O
in	O
optical	O
heterodyne	O
detection	O
.	O
</s>
<s>
This	O
allows	O
the	O
use	O
of	O
near	O
field	O
speckle	B-Algorithm
analysis	O
to	O
detect	O
the	O
scattering	O
distribution	O
;	O
this	O
is	O
the	O
so-called	O
near-field	O
scattering	O
technique	O
.	O
</s>
<s>
When	O
the	O
speckle	B-Algorithm
pattern	O
changes	O
in	O
time	O
,	O
due	O
to	O
changes	O
in	O
the	O
illuminated	O
surface	O
,	O
the	O
phenomenon	O
is	O
known	O
as	O
dynamic	O
speckle	B-Algorithm
,	O
and	O
it	O
can	O
be	O
used	O
to	O
measure	O
activity	O
,	O
by	O
means	O
of	O
,	O
for	O
example	O
,	O
an	O
optical	O
flow	O
sensor	O
(	O
optical	O
computer	O
mouse	O
)	O
.	O
</s>
<s>
In	O
a	O
static	O
environment	O
,	O
changes	O
in	O
speckle	B-Algorithm
can	O
also	O
be	O
used	O
as	O
a	O
sensitive	O
probe	O
of	O
the	O
light	O
source	O
.	O
</s>
<s>
This	O
can	O
be	O
used	O
in	O
a	O
wavemeter	O
configuration	O
,	O
with	O
a	O
resolution	O
around	O
1	O
attometre	O
,	O
(	O
equivalent	O
to	O
1	O
part	O
in	O
1012	O
of	O
the	O
wavelength	O
,	O
equivalent	O
to	O
measuring	O
the	O
length	O
of	O
a	O
football	O
field	O
at	O
the	O
resolution	O
of	O
a	O
single	O
atom	B-Language
)	O
and	O
can	O
also	O
stabilise	O
the	O
wavelength	O
of	O
lasers	O
or	O
measure	O
polarization	O
.	O
</s>
<s>
The	O
disordered	O
pattern	O
produced	O
by	O
speckle	B-Algorithm
has	O
been	O
used	O
in	O
quantum	B-Device
simulations	I-Device
with	O
cold	O
atoms	O
.	O
</s>
<s>
Adapting	O
speckle	B-Algorithm
patterns	O
for	O
use	O
in	O
these	O
applications	O
enables	O
parallel	O
3D	O
super-resolution	O
imaging	O
.	O
</s>
<s>
Speckle	B-Algorithm
is	O
considered	O
to	O
be	O
a	O
problem	O
in	O
laser	O
based	O
display	O
systems	O
like	O
the	O
Laser	B-General_Concept
TV	I-General_Concept
.	O
</s>
<s>
Speckle	B-Algorithm
is	O
usually	O
quantified	O
by	O
the	O
speckle	B-Algorithm
contrast	O
.	O
</s>
<s>
Speckle	B-Algorithm
contrast	O
reduction	O
is	O
essentially	O
the	O
creation	O
of	O
many	O
independent	O
speckle	B-Algorithm
patterns	O
,	O
so	O
that	O
they	O
average	O
out	O
on	O
the	O
retina/detector	O
.	O
</s>
<s>
Rotating	O
diffusers	O
—	O
which	O
destroys	O
the	O
spatial	O
coherence	O
of	O
the	O
laser	O
light	O
—	O
can	O
also	O
be	O
used	O
to	O
reduce	O
the	O
speckle	B-Algorithm
.	O
</s>
<s>
The	O
Mitsubishi	O
Laser	B-General_Concept
TV	I-General_Concept
appears	O
to	O
use	O
such	O
a	O
screen	O
which	O
requires	O
special	O
care	O
according	O
to	O
their	O
product	O
manual	O
.	O
</s>
<s>
A	O
more	O
detailed	O
discussion	O
on	O
laser	O
speckle	B-Algorithm
reduction	O
can	O
be	O
found	O
here	O
.	O
</s>
<s>
Synthetic	O
array	O
heterodyne	O
detection	O
was	O
developed	O
to	O
reduce	O
speckle	B-Algorithm
noise	I-Algorithm
in	O
coherent	O
optical	O
imaging	O
and	O
coherent	O
differential	O
absorption	O
LIDAR	O
.	O
</s>
<s>
In	O
scientific	O
applications	O
,	O
a	O
spatial	O
filter	O
can	O
be	O
used	O
to	O
reduce	O
speckle	B-Algorithm
.	O
</s>
<s>
Several	O
different	O
methods	O
are	O
used	O
to	O
eliminate	O
speckle	B-Algorithm
,	O
based	O
upon	O
different	O
mathematical	O
models	O
of	O
the	O
phenomenon	O
.	O
</s>
<s>
multi-look	O
processing	O
)	O
,	O
averaging	O
out	O
the	O
speckle	B-Algorithm
by	O
taking	O
several	O
"	O
looks	O
"	O
at	O
a	O
target	O
in	O
a	O
single	O
radar	B-Application
sweep	O
.	O
</s>
<s>
A	O
second	O
method	O
involves	O
using	O
adaptive	O
and	O
non-adaptive	O
filters	O
on	O
the	O
signal	O
processing	O
(	O
where	O
adaptive	O
filters	O
adapt	O
their	O
weightings	O
across	O
the	O
image	O
to	O
the	O
speckle	B-Algorithm
level	O
,	O
and	O
non-adaptive	O
filters	O
apply	O
the	O
same	O
weightings	O
uniformly	O
across	O
the	O
entire	O
image	O
)	O
.	O
</s>
<s>
Adaptive	O
speckle	B-Algorithm
filtering	O
is	O
better	O
at	O
preserving	O
edges	O
and	O
detail	O
in	O
high-texture	O
areas	O
(	O
such	O
as	O
forests	O
or	O
urban	O
areas	O
)	O
.	O
</s>
<s>
There	O
are	O
two	O
forms	O
of	O
non-adaptive	O
speckle	B-Algorithm
filtering	O
:	O
one	O
based	O
on	O
the	O
mean	O
and	O
one	O
based	O
upon	O
the	O
median	O
(	O
within	O
a	O
given	O
rectangular	O
area	O
of	O
pixels	O
in	O
the	O
image	O
)	O
.	O
</s>
<s>
There	O
are	O
many	O
forms	O
of	O
adaptive	O
speckle	B-Algorithm
filtering	O
,	O
including	O
the	O
Lee	O
filter	O
,	O
the	O
Frost	O
filter	O
,	O
and	O
the	O
refined	O
gamma	O
maximum-A-posteriori	O
(	O
RGMAP	O
)	O
filter	O
.	O
</s>
<s>
Speckle	B-Algorithm
in	O
SAR	O
is	O
a	O
multiplicative	O
,	O
i.e.	O
</s>
<s>
The	O
signal	O
and	O
the	O
speckle	B-Algorithm
are	O
statistically	O
independent	O
of	O
each	O
other	O
.	O
</s>
<s>
The	O
Lee	O
filter	O
converts	O
the	O
multiplicative	O
model	O
into	O
an	O
additive	O
one	O
,	O
thereby	O
reducing	O
the	O
problem	O
of	O
dealing	O
with	O
speckle	B-Algorithm
to	O
a	O
known	O
tractable	O
case	O
.	O
</s>
<s>
Recently	O
,	O
the	O
use	O
of	O
wavelet	B-Algorithm
transform	I-Algorithm
has	O
led	O
to	O
significant	O
advances	O
in	O
image	O
analysis	O
.	O
</s>
<s>
The	O
first	O
multiscale	O
speckle	B-Algorithm
reduction	O
methods	O
were	O
based	O
on	O
the	O
thresholding	O
of	O
detail	O
subband	O
coefficients	O
.	O
</s>
<s>
Speckle	B-Algorithm
patterns	O
can	O
also	O
be	O
observed	O
over	O
time	O
instead	O
of	O
space	O
.	O
</s>
<s>
This	O
is	O
the	O
case	O
of	O
phase	O
sensitive	O
optical	B-Protocol
time-domain	I-Protocol
reflectometry	I-Protocol
,	O
where	O
multiple	O
reflections	O
of	O
a	O
coherent	O
pulse	O
generated	O
at	O
different	O
instants	O
interfere	O
to	O
produce	O
a	O
pseudorandom	O
time-domain	O
signal	O
.	O
</s>
<s>
Speckle	B-Algorithm
interference	O
pattern	O
may	O
be	O
decomposed	O
in	O
the	O
sum	O
of	O
plane	O
waves	O
.	O
</s>
<s>
Thus	O
each	O
vortex	O
in	O
the	O
speckle	B-Algorithm
pattern	O
carries	O
optical	O
angular	O
momentum	O
.	O
</s>
<s>
Typically	O
vortices	O
appear	O
in	O
speckle	B-Algorithm
pattern	O
in	O
pairs	O
.	O
</s>
<s>
In	O
phase	O
conjugating	O
mirrors	O
based	O
on	O
stimulated	B-Algorithm
Brillouin	I-Algorithm
scattering	I-Algorithm
optical	O
vortices	O
excite	O
acoustical	O
vortices	O
.	O
</s>
<s>
Apart	O
from	O
formal	O
decomposition	O
in	O
Fourier	O
series	O
the	O
speckle	B-Algorithm
pattern	O
may	O
be	O
composed	O
for	O
plane	O
waves	O
emitted	O
by	O
tilted	O
regions	O
of	O
the	O
phase	O
plate	O
.	O
</s>
<s>
3D	O
numerical	O
emulation	O
demonstrates	O
the	O
intertwining	O
of	O
vortices	O
which	O
leads	O
to	O
formation	O
of	O
ropes	O
in	O
optical	O
speckle	B-Algorithm
.	O
</s>
