<s>
Local	B-Algorithm
binary	I-Algorithm
patterns	I-Algorithm
(	O
LBP	O
)	O
is	O
a	O
type	O
of	O
visual	B-General_Concept
descriptor	I-General_Concept
used	O
for	O
classification	O
in	O
computer	B-Application
vision	I-Application
.	O
</s>
<s>
It	O
has	O
since	O
been	O
found	O
to	O
be	O
a	O
powerful	O
feature	O
for	O
texture	O
classification	O
;	O
it	O
has	O
further	O
been	O
determined	O
that	O
when	O
LBP	O
is	O
combined	O
with	O
the	O
Histogram	B-Algorithm
of	I-Algorithm
oriented	I-Algorithm
gradients	I-Algorithm
(	O
HOG	O
)	O
descriptor	O
,	O
it	O
improves	O
the	O
detection	O
performance	O
considerably	O
on	O
some	O
datasets	O
.	O
</s>
<s>
The	O
LBP	O
feature	B-Algorithm
vector	I-Algorithm
,	O
in	O
its	O
simplest	O
form	O
,	O
is	O
created	O
in	O
the	O
following	O
manner	O
:	O
</s>
<s>
For	O
each	O
pixel	O
in	O
a	O
cell	O
,	O
compare	O
the	O
pixel	O
to	O
each	O
of	O
its	O
8	B-Algorithm
neighbors	I-Algorithm
(	O
on	O
its	O
left-top	O
,	O
left-middle	O
,	O
left-bottom	O
,	O
right-top	O
,	O
etc	O
.	O
)	O
.	O
</s>
<s>
Compute	O
the	O
histogram	B-Algorithm
,	O
over	O
the	O
cell	O
,	O
of	O
the	O
frequency	O
of	O
each	O
"	O
number	O
"	O
occurring	O
(	O
i.e.	O
,	O
each	O
combination	O
of	O
which	O
pixels	O
are	O
smaller	O
and	O
which	O
are	O
greater	O
than	O
the	O
center	O
)	O
.	O
</s>
<s>
This	O
histogram	B-Algorithm
can	O
be	O
seen	O
as	O
a	O
256-dimensional	O
feature	B-Algorithm
vector	I-Algorithm
.	O
</s>
<s>
Optionally	O
normalize	O
the	O
histogram	B-Algorithm
.	O
</s>
<s>
Concatenate	O
(	O
normalized	O
)	O
histograms	B-Algorithm
of	O
all	O
cells	O
.	O
</s>
<s>
This	O
gives	O
a	O
feature	B-Algorithm
vector	I-Algorithm
for	O
the	O
entire	O
window	O
.	O
</s>
<s>
The	O
feature	B-Algorithm
vector	I-Algorithm
can	O
now	O
be	O
processed	O
using	O
the	O
Support	B-Algorithm
vector	I-Algorithm
machine	I-Algorithm
,	O
extreme	B-Algorithm
learning	I-Algorithm
machines	I-Algorithm
,	O
or	O
some	O
other	O
machine	O
learning	O
algorithm	O
to	O
classify	O
images	O
.	O
</s>
<s>
A	O
useful	O
extension	O
to	O
the	O
original	O
operator	O
is	O
the	O
so-called	O
uniform	O
pattern	O
,	O
which	O
can	O
be	O
used	O
to	O
reduce	O
the	O
length	O
of	O
the	O
feature	B-Algorithm
vector	I-Algorithm
and	O
implement	O
a	O
simple	O
rotation	O
invariant	O
descriptor	O
.	O
</s>
<s>
In	O
the	O
computation	O
of	O
the	O
LBP	O
histogram	B-Algorithm
,	O
the	O
histogram	B-Algorithm
has	O
a	O
separate	O
bin	O
for	O
every	O
uniform	O
pattern	O
,	O
and	O
all	O
non-uniform	O
patterns	O
are	O
assigned	O
to	O
a	O
single	O
bin	O
.	O
</s>
<s>
Using	O
uniform	O
patterns	O
,	O
the	O
length	O
of	O
the	O
feature	B-Algorithm
vector	I-Algorithm
for	O
a	O
single	O
cell	O
reduces	O
from	O
256	O
to	O
59	O
.	O
</s>
<s>
Over-Complete	O
Local	B-Algorithm
Binary	I-Algorithm
Patterns	I-Algorithm
(	O
OCLBP	O
)	O
:	O
OCLBP	O
is	O
a	O
variant	O
of	O
LBP	O
that	O
has	O
been	O
shown	O
to	O
improve	O
the	O
overall	O
performance	O
on	O
face	O
verification	O
.	O
</s>
<s>
These	O
configurations	O
are	O
concatenated	O
to	O
form	O
a	O
40877	O
dimensional	O
feature	B-Algorithm
vector	I-Algorithm
for	O
an	O
image	O
of	O
size	O
150x80	O
.	O
</s>
<s>
Multi-block	O
LBP	O
:	O
the	O
image	O
is	O
divided	O
into	O
many	O
blocks	O
,	O
a	O
LBP	O
histogram	B-Algorithm
is	O
calculated	O
for	O
every	O
block	O
and	O
concatenated	O
as	O
the	O
final	O
histogram	B-Algorithm
.	O
</s>
<s>
The	O
neighborhood	O
of	O
a	O
pixel	O
is	O
thus	O
defined	O
in	O
three	O
dimensional	O
space	O
,	O
and	O
volume	O
textons	O
can	O
be	O
extracted	O
into	O
histograms	B-Algorithm
.	O
</s>
<s>
,	O
includes	O
the	O
general	O
LBP	O
and	O
many	O
further	O
extensions	O
over	O
LBP	O
histogram	B-Algorithm
in	O
MATLAB	O
.	O
</s>
<s>
,	O
an	O
open	O
source	O
computer	B-Application
vision	I-Application
package	O
which	O
includes	O
an	O
implementation	O
of	O
LBPs	O
.	O
</s>
<s>
OpenCV	B-Language
's	O
Cascade	O
Classifiers	O
support	O
LBPs	O
as	O
of	O
version	O
2	O
.	O
</s>
<s>
,	O
an	O
open	O
source	O
computer	B-Application
vision	I-Application
library	O
in	O
C	O
(	O
with	O
bindings	O
to	O
multiple	O
languages	O
including	O
MATLAB	O
)	O
has	O
an	O
.	O
</s>
<s>
is	O
a	O
collection	O
of	O
eleven	O
Local	B-Algorithm
Binary	I-Algorithm
Patterns	I-Algorithm
(	O
LBP	O
)	O
algorithms	O
developed	O
for	O
background	O
subtraction	O
problem	O
.	O
</s>
<s>
The	O
algorithms	O
were	O
implemented	O
in	O
C++	O
based	O
on	O
OpenCV	B-Language
.	O
</s>
<s>
The	O
library	O
was	O
tested	O
successfully	O
with	O
OpenCV	B-Language
2.4.10	O
.	O
</s>
