<s>
Modified	B-Algorithm
Huffman	I-Algorithm
coding	I-Algorithm
is	O
used	O
in	O
fax	O
machines	O
to	O
encode	O
black-on-white	O
images	O
(	O
bitmaps	O
)	O
.	O
</s>
<s>
It	O
combines	O
the	O
variable-length	O
codes	O
of	O
Huffman	B-General_Concept
coding	I-General_Concept
with	O
the	O
coding	O
of	O
repetitive	O
data	O
in	O
run-length	B-Algorithm
encoding	I-Algorithm
.	O
</s>
<s>
The	O
basic	O
Huffman	B-General_Concept
coding	I-General_Concept
provides	O
a	O
way	O
to	O
compress	O
files	O
that	O
have	O
much	O
repeating	O
data	O
,	O
like	O
a	O
file	O
containing	O
text	O
,	O
where	O
the	O
alphabet	O
letters	O
are	O
the	O
repeating	O
objects	O
.	O
</s>
<s>
This	O
"	O
alphabet	O
"	O
of	O
only	O
two	O
symbols	O
is	O
too	O
small	O
to	O
directly	O
apply	O
the	O
Huffman	B-General_Concept
coding	I-General_Concept
.	O
</s>
<s>
But	O
if	O
we	O
first	O
use	O
run-length	B-Algorithm
encoding	I-Algorithm
,	O
we	O
can	O
have	O
more	O
objects	O
to	O
encode	O
.	O
</s>
<s>
Here	O
is	O
an	O
example	O
taken	O
from	O
the	O
article	O
on	O
run-length	B-Algorithm
encoding	I-Algorithm
:	O
</s>
<s>
With	O
a	O
run-length	B-Algorithm
encoding	I-Algorithm
(	O
RLE	O
)	O
data	O
compression	O
algorithm	O
applied	O
to	O
the	O
above	O
hypothetical	O
scan	O
line	O
,	O
it	O
can	O
be	O
rendered	O
as	O
follows	O
:	O
</s>
<s>
These	O
numbers	O
provide	O
plenty	O
of	O
additional	O
items	O
to	O
use	O
,	O
so	O
the	O
Huffman	B-General_Concept
coding	I-General_Concept
can	O
be	O
directly	O
applied	O
to	O
the	O
sequence	O
above	O
to	O
reduce	O
the	O
size	O
even	O
more	O
.	O
</s>
