<s>
Atkinson	B-Algorithm
dithering	I-Algorithm
is	O
a	O
variant	O
of	O
Floyd-Steinberg	B-Algorithm
dithering	I-Algorithm
designed	O
by	O
Bill	O
Atkinson	O
at	O
Apple	O
Computer	O
,	O
and	O
used	O
in	O
the	O
original	O
Macintosh	B-Device
computer	I-Device
.	O
</s>
<s>
The	O
algorithm	O
achieves	O
dithering	O
using	O
error	B-Algorithm
diffusion	I-Algorithm
,	O
meaning	O
it	O
pushes	O
(	O
adds	O
)	O
the	O
residual	O
quantization	O
error	O
of	O
a	O
pixel	B-Algorithm
onto	O
its	O
neighboring	O
pixels	B-Algorithm
,	O
to	O
be	O
dealt	O
with	O
later	O
.	O
</s>
<s>
It	O
spreads	O
the	O
debt	O
out	O
according	O
to	O
the	O
distribution	O
(	O
shown	O
as	O
a	O
map	O
of	O
the	O
neighboring	O
pixels	B-Algorithm
)	O
:	O
</s>
<s>
The	O
pixel	B-Algorithm
indicated	O
with	O
a	O
star	O
( *	O
)	O
indicates	O
the	O
pixel	B-Algorithm
currently	O
being	O
scanned	O
,	O
and	O
the	O
blank	O
pixels	B-Algorithm
are	O
the	O
previously	O
scanned	O
pixels	B-Algorithm
.	O
</s>
<s>
The	O
algorithm	O
scans	O
the	O
image	O
from	O
left	O
to	O
right	O
,	O
top	O
to	O
bottom	O
,	O
quantizing	O
pixel	B-Algorithm
values	O
one	O
by	O
one	O
.	O
</s>
<s>
Each	O
time	O
the	O
quantization	O
error	O
is	O
transferred	O
to	O
the	O
neighboring	O
pixels	B-Algorithm
,	O
while	O
not	O
affecting	O
the	O
pixels	B-Algorithm
that	O
already	O
have	O
been	O
quantized	O
.	O
</s>
<s>
Hence	O
,	O
if	O
a	O
number	O
of	O
pixels	B-Algorithm
have	O
been	O
rounded	O
downwards	O
,	O
it	O
becomes	O
more	O
likely	O
that	O
the	O
next	O
pixel	B-Algorithm
is	O
rounded	O
upwards	O
,	O
such	O
that	O
on	O
average	O
,	O
the	O
quantization	O
error	O
is	O
reduced	O
.	O
</s>
<s>
Unlike	O
Floyd-Steinberg	B-Algorithm
dithering	I-Algorithm
,	O
only	O
3/4	O
of	O
the	O
error	O
is	O
diffused	O
outward	O
.	O
</s>
