<s>
A	O
scanning	B-Device
back	I-Device
is	O
a	O
type	O
of	O
digital	B-Algorithm
camera	I-Algorithm
back	I-Algorithm
.	O
</s>
<s>
Digital	B-Algorithm
imaging	I-Algorithm
devices	O
typically	O
use	O
a	O
matrix	O
of	O
light-sensitive	O
photosensors	O
,	O
such	O
as	O
CCD	B-Algorithm
or	O
CMOS	B-Device
technologies	O
.	O
</s>
<s>
These	O
sensors	O
can	O
be	O
arranged	O
in	O
different	O
ways	O
,	O
like	O
a	O
Bayer	B-Algorithm
filter	I-Algorithm
,	O
where	O
each	O
row	O
captures	O
RGB	O
components	O
,	O
or	O
using	O
one	O
full-sized	O
layer	O
for	O
each	O
color	O
,	O
such	O
as	O
the	O
Foveon	B-Algorithm
X3	I-Algorithm
sensor	I-Algorithm
.	O
</s>
<s>
A	O
digital	B-Device
scan	I-Device
back	I-Device
takes	O
a	O
similar	O
approach	O
to	O
the	O
second	O
type	O
of	O
photosensor	O
,	O
but	O
instead	O
of	O
using	O
one	O
matrix	O
for	O
each	O
component	O
,	O
it	O
uses	O
one	O
array	O
per	O
component	O
.	O
</s>
<s>
A	O
somewhat	O
less	O
obvious	O
advantage	O
lies	O
in	O
that	O
scanning	B-Device
backs	I-Device
are	O
typically	O
created	O
using	O
trilinear	O
CCD	B-Algorithm
's	O
.	O
</s>
<s>
A	O
4	O
GB	O
Compact	B-Device
Flash	I-Device
card	O
can	O
only	O
store	O
a	O
handful	O
of	O
images	O
.	O
</s>
<s>
The	O
first	O
commercial	O
digital	B-Device
scan	I-Device
back	I-Device
was	O
introduced	O
by	O
Leaf	O
(	O
now	O
Phase	O
One	O
)	O
in	O
1991	O
.	O
</s>
<s>
For	O
a	O
further	O
outline	O
of	O
the	O
history	O
of	O
scanning	B-Device
backs	I-Device
see	O
Digital	B-Algorithm
camera	I-Algorithm
back	I-Algorithm
.	O
</s>
