<s>
Data	B-General_Concept
conversion	I-General_Concept
is	O
the	O
conversion	O
of	O
computer	B-General_Concept
data	I-General_Concept
from	O
one	O
format	O
to	O
another	O
.	O
</s>
<s>
Throughout	O
a	O
computer	O
environment	O
,	O
data	O
is	O
encoded	B-General_Concept
in	O
a	O
variety	O
of	O
ways	O
.	O
</s>
<s>
For	O
example	O
,	O
computer	B-Architecture
hardware	I-Architecture
is	O
built	O
on	O
the	O
basis	O
of	O
certain	O
standards	O
,	O
which	O
requires	O
that	O
data	O
contains	O
,	O
for	O
example	O
,	O
parity	B-Error_Name
bit	I-Error_Name
checks	O
.	O
</s>
<s>
Similarly	O
,	O
the	O
operating	B-General_Concept
system	I-General_Concept
is	O
predicated	O
on	O
certain	O
standards	O
for	O
data	O
and	O
file	O
handling	O
.	O
</s>
<s>
Whenever	O
any	O
one	O
of	O
these	O
variables	O
is	O
changed	O
,	O
data	O
must	O
be	O
converted	O
in	O
some	O
way	O
before	O
it	O
can	O
be	O
used	O
by	O
a	O
different	O
computer	O
,	O
operating	B-General_Concept
system	I-General_Concept
or	O
program	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
changing	O
of	O
bits	O
from	O
one	O
format	O
to	O
another	O
,	O
usually	O
for	O
the	O
purpose	O
of	O
application	O
interoperability	O
or	O
of	O
the	O
capability	O
of	O
using	O
new	O
features	O
,	O
is	O
merely	O
a	O
data	B-General_Concept
conversion	I-General_Concept
.	O
</s>
<s>
Data	B-General_Concept
conversions	I-General_Concept
may	O
be	O
as	O
simple	O
as	O
the	O
conversion	O
of	O
a	O
text	B-General_Concept
file	I-General_Concept
from	O
one	O
character	B-General_Concept
encoding	I-General_Concept
system	I-General_Concept
to	O
another	O
;	O
or	O
more	O
complex	O
,	O
such	O
as	O
the	O
conversion	O
of	O
office	O
file	O
formats	O
,	O
or	O
the	O
conversion	B-Application
of	I-Application
image	I-Application
formats	I-Application
and	O
audio	O
file	O
formats	O
.	O
</s>
<s>
Alternatively	O
,	O
the	O
conversion	O
may	O
require	O
processing	O
by	O
the	O
use	O
of	O
a	O
special	O
conversion	O
program	O
,	O
or	O
it	O
may	O
involve	O
a	O
complex	O
process	O
of	O
going	O
through	O
intermediary	O
stages	O
,	O
or	O
involving	O
complex	O
"	O
exporting	O
"	O
and	O
"	O
importing	O
"	O
procedures	O
,	O
which	O
may	O
include	O
converting	O
to	O
and	O
from	O
a	O
tab-delimited	O
or	O
comma-separated	O
text	B-General_Concept
file	I-General_Concept
.	O
</s>
<s>
Before	O
any	O
data	B-General_Concept
conversion	I-General_Concept
is	O
carried	O
out	O
,	O
the	O
user	O
or	O
application	O
programmer	O
should	O
keep	O
a	O
few	O
basics	O
of	O
computing	O
and	O
information	O
theory	O
in	O
mind	O
.	O
</s>
<s>
Upsampling	O
the	O
data	O
or	O
converting	O
to	O
a	O
more	O
feature-rich	B-Architecture
format	O
does	O
not	O
add	O
information	O
;	O
it	O
merely	O
makes	O
room	O
for	O
that	O
addition	O
,	O
which	O
usually	O
a	O
human	O
must	O
do	O
.	O
</s>
<s>
Converting	O
a	O
Unix	B-Application
text	B-General_Concept
file	I-General_Concept
to	O
a	O
Microsoft	O
(	O
DOS/Windows	O
)	O
text	B-General_Concept
file	I-General_Concept
involves	O
adding	O
characters	O
,	O
but	O
this	O
does	O
not	O
increase	O
the	O
entropy	O
since	O
it	O
is	O
rule-based	O
;	O
whereas	O
the	O
addition	O
of	O
color	O
information	O
to	O
a	O
grayscale	O
image	O
cannot	O
be	O
reliably	O
done	O
programmatically	O
,	O
as	O
it	O
requires	O
adding	O
new	O
information	O
,	O
so	O
any	O
attempt	O
to	O
add	O
color	O
would	O
require	O
estimation	B-Application
by	O
the	O
computer	O
based	O
on	O
previous	O
knowledge	O
.	O
</s>
<s>
Converting	O
an	O
image	O
or	O
audio	O
file	O
in	O
a	O
lossy	B-Algorithm
format	O
(	O
like	O
JPEG	O
or	O
Vorbis	B-Algorithm
)	O
to	O
a	O
lossless	B-Algorithm
(	O
like	O
PNG	O
or	O
FLAC	B-Application
)	O
or	O
uncompressed	O
(	O
like	O
BMP	B-Device
or	O
WAV	O
)	O
format	O
only	O
wastes	O
space	O
,	O
since	O
the	O
same	O
image	O
with	O
its	O
loss	O
of	O
original	O
information	O
(	O
the	O
artifacts	B-Algorithm
of	O
lossy	B-Algorithm
compression	I-Algorithm
)	O
becomes	O
the	O
target	O
.	O
</s>
<s>
A	O
JPEG	O
image	O
can	O
never	O
be	O
restored	O
to	O
the	O
quality	O
of	O
the	O
original	O
image	O
from	O
which	O
it	O
was	O
made	O
,	O
no	O
matter	O
how	O
much	O
the	O
user	O
tries	O
the	O
"	O
JPEG	B-Algorithm
Artifact	I-Algorithm
Removal	O
"	O
feature	O
of	O
his	O
or	O
her	O
image	O
manipulation	O
program	O
.	O
</s>
<s>
Automatic	O
restoration	O
of	O
information	O
that	O
was	O
lost	O
through	O
a	O
lossy	B-Algorithm
compression	I-Algorithm
process	O
would	O
probably	O
require	O
important	O
advances	O
in	O
artificial	B-Application
intelligence	I-Application
.	I-Application
</s>
<s>
Because	O
of	O
these	O
realities	O
of	O
computing	O
and	O
information	O
theory	O
,	O
data	B-General_Concept
conversion	I-General_Concept
is	O
often	O
a	O
complex	O
and	O
error-prone	O
process	O
that	O
requires	O
the	O
help	O
of	O
experts	O
.	O
</s>
<s>
Data	B-General_Concept
conversion	I-General_Concept
can	O
occur	O
directly	O
from	O
one	O
format	O
to	O
another	O
,	O
but	O
many	O
applications	O
that	O
convert	O
between	O
multiple	O
formats	O
use	O
an	O
intermediate	B-Application
representation	I-Application
by	O
way	O
of	O
which	O
any	O
source	O
format	O
is	O
converted	O
to	O
its	O
target	O
.	O
</s>
<s>
This	O
is	O
a	O
more	O
manageable	O
approach	O
;	O
rather	O
than	O
needing	O
lookup	O
tables	O
for	O
all	O
possible	O
pairs	O
of	O
character	B-General_Concept
encodings	I-General_Concept
,	O
an	O
application	O
needs	O
only	O
one	O
lookup	O
table	O
for	O
each	O
character	B-General_Concept
set	I-General_Concept
,	O
which	O
it	O
uses	O
to	O
convert	O
to	O
and	O
from	O
Unicode	O
,	O
thereby	O
scaling	O
the	O
number	O
of	O
tables	O
down	O
from	O
hundreds	O
to	O
a	O
few	O
tens	O
.	O
</s>
<s>
For	O
example	O
,	O
a	O
word	B-General_Concept
processor	I-General_Concept
may	O
convert	O
an	O
RTF	O
file	O
to	O
a	O
WordPerfect	B-Application
file	O
by	O
converting	O
the	O
RTF	O
to	O
OpenDocument	B-Application
and	O
then	O
that	O
to	O
WordPerfect	B-Application
format	O
.	O
</s>
<s>
An	O
image	B-Application
conversion	I-Application
program	O
does	O
not	O
convert	O
a	O
PCX	O
image	O
to	O
PNG	O
directly	O
;	O
instead	O
,	O
when	O
loading	O
the	O
PCX	O
image	O
,	O
it	O
decodes	O
it	O
to	O
a	O
simple	O
bitmap	O
format	O
for	O
internal	O
use	O
in	O
memory	O
,	O
and	O
when	O
commanded	O
to	O
convert	O
to	O
PNG	O
,	O
that	O
memory	O
image	O
is	O
converted	O
to	O
the	O
target	O
format	O
.	O
</s>
<s>
An	O
audio	O
converter	O
that	O
converts	O
from	O
FLAC	B-Application
to	O
AAC	B-Application
decodes	O
the	O
source	O
file	O
to	O
raw	O
PCM	B-Algorithm
data	O
in	O
memory	O
first	O
,	O
and	O
then	O
performs	O
the	O
lossy	B-Algorithm
AAC	B-Application
compression	O
on	O
that	O
memory	O
image	O
to	O
produce	O
the	O
target	O
file	O
.	O
</s>
<s>
The	O
objective	O
of	O
data	B-General_Concept
conversion	I-General_Concept
is	O
to	O
maintain	O
all	O
of	O
the	O
data	O
,	O
and	O
as	O
much	O
of	O
the	O
embedded	O
information	O
as	O
possible	O
.	O
</s>
<s>
Conversion	O
of	O
a	O
word	O
processing	O
document	O
to	O
a	O
plain	O
text	B-General_Concept
file	I-General_Concept
necessarily	O
involves	O
loss	O
of	O
formatting	O
information	O
,	O
because	O
plain	O
text	O
format	O
does	O
not	O
support	O
word	O
processing	O
constructs	O
such	O
as	O
marking	O
a	O
word	O
as	O
boldface	O
.	O
</s>
<s>
converting	O
a	O
file	O
from	O
one	O
version	O
of	O
Microsoft	B-Application
Word	I-Application
to	O
an	O
earlier	O
version	O
to	O
enable	O
transfer	O
and	O
use	O
by	O
other	O
users	O
who	O
do	O
not	O
have	O
the	O
same	O
later	O
version	O
of	O
Word	O
installed	O
on	O
their	O
computer	O
.	O
</s>
<s>
There	O
is	O
no	O
way	O
of	O
converting	O
a	O
character	O
like	O
ä	O
to	O
ASCII	B-Protocol
,	O
since	O
the	O
ASCII	B-Protocol
standard	O
lacks	O
it	O
,	O
but	O
the	O
information	O
may	O
be	O
retained	O
by	O
approximating	O
the	O
character	O
as	O
ae	O
.	O
</s>
<s>
Data	B-General_Concept
conversion	I-General_Concept
can	O
also	O
suffer	O
from	O
inexactitude	O
,	O
the	O
result	O
of	O
converting	O
between	O
formats	O
that	O
are	O
conceptually	O
different	O
.	O
</s>
<s>
The	O
WYSIWYG	B-Application
paradigm	O
,	O
extant	O
in	O
word	B-General_Concept
processors	I-General_Concept
and	O
desktop	O
publishing	O
applications	O
,	O
versus	O
the	O
structural-descriptive	O
paradigm	O
,	O
found	O
in	O
SGML	B-Language
,	O
XML	B-Protocol
and	O
many	O
applications	O
derived	O
therefrom	O
,	O
like	O
HTML	B-Language
and	O
MathML	B-Language
,	O
is	O
one	O
example	O
.	O
</s>
<s>
Using	O
a	O
WYSIWYG	B-Application
HTML	B-Language
editor	O
conflates	O
the	O
two	O
paradigms	O
,	O
and	O
the	O
result	O
is	O
HTML	B-Language
files	I-Language
with	O
suboptimal	O
,	O
if	O
not	O
nonstandard	O
,	O
code	O
.	O
</s>
<s>
In	O
the	O
WYSIWYG	B-Application
paradigm	O
a	O
double	O
linebreak	O
signifies	O
a	O
new	O
paragraph	O
,	O
as	O
that	O
is	O
the	O
visual	O
cue	O
for	O
such	O
a	O
construct	O
,	O
but	O
a	O
WYSIWYG	B-Application
HTML	B-Language
editor	O
will	O
usually	O
convert	O
such	O
a	O
sequence	O
to	O
<BR><BR>	O
,	O
which	O
is	O
structurally	O
no	O
new	O
paragraph	O
at	O
all	O
.	O
</s>
<s>
As	O
another	O
example	O
,	O
converting	O
from	O
PDF	B-Application
to	O
an	O
editable	O
word	B-General_Concept
processor	I-General_Concept
format	O
is	O
a	O
tough	O
chore	O
,	O
because	O
PDF	B-Application
records	O
the	O
textual	O
information	O
like	O
engraving	O
on	O
stone	O
,	O
with	O
each	O
character	O
given	O
a	O
fixed	O
position	O
and	O
linebreaks	O
hard-coded	O
,	O
whereas	O
word	B-General_Concept
processor	I-General_Concept
formats	O
accommodate	O
text	O
reflow	O
.	O
</s>
<s>
PDF	B-Application
does	O
not	O
know	O
of	O
a	O
word	O
space	O
character	O
—	O
the	O
space	O
between	O
two	O
letters	O
and	O
the	O
space	O
between	O
two	O
words	O
differ	O
only	O
in	O
quantity	O
.	O
</s>
<s>
Therefore	O
,	O
a	O
title	O
with	O
ample	O
letter-spacing	O
for	O
effect	O
will	O
usually	O
end	O
up	O
with	O
spaces	O
in	O
the	O
word	B-General_Concept
processor	I-General_Concept
file	O
,	O
for	O
example	O
INTRODUCTION	O
with	O
spacing	O
of	O
1	O
em	O
as	O
I	O
N	O
T	O
R	O
O	O
D	O
U	O
C	O
T	O
I	O
O	O
N	O
on	O
the	O
word	B-General_Concept
processor	I-General_Concept
.	O
</s>
<s>
Successful	O
data	B-General_Concept
conversion	I-General_Concept
requires	O
thorough	O
knowledge	O
of	O
the	O
workings	O
of	O
both	O
source	O
and	O
target	O
formats	O
.	O
</s>
<s>
Data	O
format	B-General_Concept
conversion	I-General_Concept
can	O
also	O
occur	O
at	O
the	O
physical	O
layer	O
of	O
an	O
electronic	O
communication	O
system	O
.	O
</s>
<s>
Conversion	O
between	O
line	B-Protocol
codes	I-Protocol
such	O
as	O
NRZ	B-Protocol
and	O
RZ	B-Protocol
can	O
be	O
accomplished	O
when	O
necessary	O
.	O
</s>
