<s>
Document	B-Application
cameras	I-Application
,	O
also	O
known	O
as	O
visual	B-Application
presenters	I-Application
,	O
visualizers	B-Application
,	O
digital	B-Application
overheads	I-Application
,	O
or	O
docucams	B-Application
,	O
are	O
real-time	O
image	O
capture	O
devices	O
for	O
displaying	O
an	O
object	O
to	O
a	O
large	O
audience	O
.	O
</s>
<s>
Like	O
an	O
opaque	B-General_Concept
projector	I-General_Concept
,	O
a	O
document	B-Application
camera	I-Application
is	O
able	O
to	O
magnify	O
and	O
project	O
the	O
images	O
of	O
actual	O
,	O
three-dimensional	O
objects	O
,	O
as	O
well	O
as	O
transparencies	O
.	O
</s>
<s>
They	O
are	O
,	O
in	O
essence	O
,	O
high	B-Algorithm
resolution	I-Algorithm
web	B-Protocol
cams	I-Protocol
,	O
mounted	O
on	O
arms	O
so	O
as	O
to	O
facilitate	O
their	O
placement	O
over	O
a	O
page	O
.	O
</s>
<s>
Theoretically	O
,	O
all	O
objects	O
can	O
be	O
displayed	O
by	O
a	O
document	B-Application
camera	I-Application
.	O
</s>
<s>
The	O
camera	O
takes	O
the	O
picture	O
which	O
in	O
turn	O
produces	O
a	O
live	O
picture	O
using	O
a	O
projector	B-Device
or	O
monitor	O
.	O
</s>
<s>
Different	O
types	O
of	O
document	O
camera/visualizer	O
allow	O
great	O
flexibility	O
in	O
terms	O
of	O
placement	O
of	O
objects	O
.	O
</s>
<s>
Larger	O
objects	O
,	O
for	O
example	O
,	O
can	O
simply	O
be	O
placed	O
in	O
front	O
of	O
the	O
camera	O
and	O
the	O
camera	O
rotated	O
as	O
necessary	O
,	O
or	O
a	O
ceiling	O
mounted	O
document	B-Application
camera	I-Application
can	O
also	O
be	O
used	O
to	O
allow	O
a	O
larger	O
working	O
area	O
to	O
be	O
used	O
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
replaced	O
epidiascopes	B-General_Concept
and	O
overhead	B-Device
projectors	I-Device
,	O
which	O
were	O
formerly	O
used	O
for	O
this	O
purpose	O
.	O
</s>
<s>
By	O
means	O
of	O
the	O
zoom	O
feature	O
a	O
document	B-Application
camera	I-Application
can	O
enlarge	O
the	O
small	O
print	O
in	O
books	O
and	O
project	O
a	O
printed	O
page	O
as	O
if	O
it	O
were	O
a	O
traditional	O
transparency	O
.	O
</s>
<s>
Also	O
,	O
the	O
room	O
lighting	O
does	O
not	O
have	O
to	O
be	O
darkened	O
to	O
operate	O
a	O
document	B-Application
camera	I-Application
;	O
in	O
a	O
classroom	O
setting	O
this	O
is	O
an	O
asset	O
.	O
</s>
<s>
Most	O
document	B-Application
cameras	I-Application
can	O
also	O
send	O
a	O
video	B-Application
signal	I-Application
to	O
a	O
computer	O
via	O
USB	B-Protocol
cable	O
.	O
</s>
<s>
Sometimes	O
document	B-Application
cameras	I-Application
are	O
connected	O
to	O
an	O
interactive	B-Application
whiteboard	I-Application
instead	O
of	O
a	O
standard	O
screen	O
.	O
</s>
<s>
Some	O
document	B-Application
cameras	I-Application
can	O
be	O
supplied	O
with	O
an	O
accessory	O
so	O
that	O
they	O
can	O
be	O
used	O
with	O
a	O
microscope	O
.	O
</s>
<s>
,	O
camera	O
sensors	O
in	O
document	B-Application
cameras	I-Application
are	O
mostly	O
providing	O
either	O
720pHD	O
(	O
1280x720	O
pixels	O
)	O
or	O
1080pHD	O
(	O
1920x1080	O
pixels	O
)	O
native	O
image	B-Algorithm
resolution	I-Algorithm
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
were	O
developed	O
to	O
meet	O
an	O
increased	O
demand	O
for	O
the	O
ability	O
to	O
project	O
and	O
present	O
original	O
documents	O
,	O
plans	O
,	O
drawings	O
and	O
objects	O
directly	O
,	O
rather	O
than	O
necessitating	O
the	O
prior	O
preparation	O
,	O
that	O
would	O
be	O
required	O
for	O
their	O
use	O
as	O
part	O
of	O
an	O
overhead	O
projector-based	O
presentation	O
.	O
</s>
<s>
The	O
first	O
Visualizer/document	O
camera	O
were	O
developed	O
by	O
the	O
companies	O
WolfVision	O
and	O
Elmo	O
and	O
were	O
launched	O
at	O
the	O
photokina	O
Trade	O
Fair	O
in	O
1988	O
.	O
</s>
<s>
The	O
widespread	O
use	O
of	O
computers	O
,	O
projectors	O
,	O
and	O
popular	O
presentation	O
programs	O
such	O
as	O
Microsoft	B-Application
PowerPoint	I-Application
in	O
meeting	O
rooms	O
,	O
meant	O
that	O
overhead	B-Device
projectors	I-Device
became	O
less	O
frequently	O
used	O
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
continue	O
to	O
provide	O
a	O
convenient	O
and	O
flexible	O
way	O
of	O
allowing	O
documents	O
,	O
books	O
or	O
slides	O
to	O
be	O
spontaneously	O
displayed	O
during	O
presentations	O
as	O
required	O
.	O
</s>
<s>
The	O
technology	O
of	O
video	O
cameras	O
during	O
this	O
time	O
,	O
was	O
a	O
key	O
factor	O
in	O
the	O
development	O
of	O
document	B-Application
camera	I-Application
systems	O
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
have	O
also	O
frequently	O
benefited	O
from	O
developments	O
in	O
other	O
industries	O
,	O
which	O
also	O
facilitated	O
significant	O
advances	O
in	O
the	O
field	O
of	O
document	B-Application
camera	I-Application
technology	O
.	O
</s>
<s>
A	O
good	O
example	O
of	O
this	O
is	O
the	O
technology	O
used	O
in	O
photographic	O
equipment	O
,	O
which	O
has	O
contributed	O
much	O
to	O
the	O
development	O
of	O
the	O
document	B-Application
camera	I-Application
as	O
a	O
high-quality	O
presentation	O
tool	O
.	O
</s>
<s>
Many	O
visualizers	B-Application
available	O
on	O
the	O
market	O
today	O
are	O
capable	O
of	O
at	O
least	O
30	O
frames	O
per	O
second	O
output	O
,	O
which	O
ensures	O
high	O
quality	O
imaging	O
and	O
smoothness	O
of	O
motion	O
in	O
all	O
resolutions	O
and	O
aspect	O
ratios	O
.	O
</s>
<s>
The	O
design	O
and	O
specification	O
of	O
a	O
document	B-Application
camera	I-Application
are	O
a	O
combination	O
of	O
several	O
different	O
technologies	O
.	O
</s>
<s>
The	O
quality	O
of	O
the	O
recorded	O
image	O
is	O
dependent	O
on	O
the	O
primary	O
components	O
,	O
which	O
are	O
:	O
optics	O
,	O
camera	O
,	O
lighting	O
system	O
and	O
motherboard	B-Device
with	O
appropriate	O
firmware	B-Application
(	O
software	O
)	O
.	O
</s>
<s>
Today	O
High-Definition	O
Document	B-Application
cameras	I-Application
are	O
available	O
with	O
HDMI	B-Protocol
output	O
,	O
Audio/Video	O
recording	O
and	O
playback	O
is	O
possible	O
,	O
and	O
some	O
High-Definition	O
document	B-Application
cameras	I-Application
are	O
also	O
using	O
high-speed	O
WIFI	O
technology	O
to	O
eliminate	O
the	O
need	O
for	O
cables	O
.	O
</s>
<s>
This	O
complex	O
camera	O
technology	O
is	O
used	O
in	O
3-chip	O
cameras	O
and	O
allows	O
for	O
excellent	O
colour	O
reproduction	O
at	O
very	O
high	B-Algorithm
resolutions	I-Algorithm
.	O
</s>
<s>
Modern	O
camera	O
systems	O
used	O
in	O
a	O
document	B-Application
camera	I-Application
are	O
able	O
to	O
provide	O
high-resolution	B-Algorithm
colour	O
images	O
at	O
30	O
frames	O
per	O
second	O
.	O
</s>
<s>
Lighting	O
is	O
an	O
essential	O
part	O
of	O
a	O
document	B-Application
camera	I-Application
.	O
</s>
<s>
The	O
greater	O
the	O
light	O
intensity	O
,	O
the	O
more	O
independent	O
the	O
document	B-Application
camera	I-Application
is	O
from	O
ambient	O
light	O
sources	O
.	O
</s>
<s>
Using	O
powerful	O
lighting	O
systems	O
enables	O
smaller	O
apertures	O
to	O
be	O
used	O
,	O
and	O
this	O
in	O
turn	O
provides	O
a	O
significant	O
increase	O
in	O
the	O
depth	O
of	O
field	O
that	O
can	O
be	O
achieved	O
by	O
the	O
document	B-Application
camera	I-Application
.	O
</s>
<s>
Some	O
document	B-Application
camera	I-Application
models	O
integrate	O
additional	O
functionality	O
into	O
the	O
light	O
system	O
,	O
such	O
as	O
a	O
synchronized	O
light	O
field	O
that	O
clearly	O
indicates	O
to	O
the	O
user	O
at	O
all	O
times	O
,	O
by	O
way	O
of	O
an	O
illuminated	O
image	O
capture	O
area	O
or	O
laser	O
markers	O
,	O
the	O
size	O
and	O
position	O
of	O
the	O
imaging	O
area	O
,	O
which	O
adjusts	O
simultaneously	O
as	O
the	O
lens	O
zooms	O
in	O
or	O
out	O
.	O
</s>
<s>
The	O
motherboard	B-Device
plays	O
an	O
important	O
role	O
in	O
image	B-Algorithm
processing	I-Algorithm
and	O
it	O
has	O
a	O
major	O
influence	O
on	O
the	O
quality	O
of	O
the	O
eventual	O
image	O
that	O
is	O
produced	O
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
have	O
a	O
wide	O
variety	O
of	O
sophisticated	O
automated	O
systems	O
that	O
are	O
designed	O
to	O
make	O
the	O
user	O
experience	O
as	O
easy	O
as	O
possible	O
.	O
</s>
<s>
A	O
document	B-Application
camera	I-Application
needs	O
an	O
image	O
display	O
device	O
to	O
show	O
the	O
information	O
to	O
the	O
audience	O
.	O
</s>
<s>
Modern	O
motherboards	B-Device
have	O
a	O
variety	O
of	O
connections	O
to	O
ensure	O
flexibility	O
of	O
use	O
.	O
</s>
<s>
In	O
addition	O
to	O
HDMI	B-Protocol
,	O
DVI	B-Protocol
,	O
VGA	B-Protocol
ports	O
for	O
connecting	O
to	O
displays	O
,	O
(	O
projectors	O
,	O
monitors	O
and	O
video	B-Application
conferencing	I-Application
systems	O
)	O
there	O
are	O
also	O
several	O
interfaces	O
provided	O
to	O
facilitate	O
connection	O
to	O
a	O
computer	O
or	O
interactive	B-Application
whiteboard	I-Application
.	O
</s>
<s>
These	O
interfaces	O
are	O
most	O
commonly	O
USB	B-Protocol
,	O
Network	O
(	O
LAN	O
)	O
and	O
serial	O
.	O
</s>
<s>
In	O
addition	O
,	O
an	O
external	O
PC	O
or	O
laptop	O
can	O
be	O
connected	O
to	O
the	O
document	B-Application
camera	I-Application
to	O
allow	O
for	O
switching	O
between	O
a	O
Power	B-Application
Point	I-Application
presentation	O
and	O
a	O
live	O
demonstration	O
.	O
</s>
<s>
Some	O
models	O
can	O
also	O
handle	O
external	O
storage	O
devices	O
and	O
play	O
files	O
directly	O
from	O
a	O
USB	B-Protocol
flash	O
drive	O
,	O
or	O
save	O
images	O
taken	O
during	O
the	O
presentation	O
onto	O
it	O
.	O
</s>
<s>
Some	O
document	B-Application
camera	I-Application
manufacturers	O
also	O
provide	O
for	O
regular	O
firmware	B-Application
upgrades	O
,	O
allowing	O
users	O
to	O
have	O
the	O
opportunity	O
to	O
be	O
equipped	O
with	O
,	O
and	O
benefit	O
from	O
new	O
features	O
as	O
they	O
become	O
available	O
.	O
</s>
<s>
Document	B-Application
cameras	I-Application
are	O
generally	O
divided	O
into	O
three	O
groups	O
.	O
</s>
<s>
Smaller	O
lightweight	O
models	O
are	O
considered	O
portable	O
,	O
larger	O
sturdier	O
and	O
more	O
stable	O
units	O
are	O
known	O
as	O
desktop	O
models	O
,	O
and	O
the	O
third	O
group	O
are	O
ceiling	O
visualizers	B-Application
.	O
</s>
<s>
Portable	O
and	O
desktop	O
models	O
allow	O
a	O
similar	O
working	O
environment	O
to	O
that	O
of	O
an	O
overhead	B-Device
projector	I-Device
.	O
</s>
<s>
Many	O
document	B-Application
camera	I-Application
users	O
appreciate	O
the	O
added	O
flexibility	O
in	O
terms	O
of	O
the	O
variety	O
of	O
objects	O
that	O
can	O
be	O
displayed	O
to	O
an	O
audience	O
.	O
</s>
<s>
Ceiling-mounted	O
document	O
cameras/visualizers	O
are	O
a	O
variation	O
from	O
the	O
traditional	O
desktop	O
models	O
and	O
allow	O
for	O
larger	O
objects	O
to	O
be	O
displayed	O
.	O
</s>
<s>
Ceiling	O
models	O
are	O
often	O
used	O
to	O
support	O
videoconferencing	B-Application
or	O
telepresence	B-Application
systems	O
to	O
further	O
enhance	O
the	O
immersive	O
experience	O
for	O
participants	O
.	O
</s>
