<s>
In	O
data	B-General_Concept
compression	I-General_Concept
and	O
psychoacoustics	O
,	O
transparency	B-Algorithm
is	O
the	O
result	O
of	O
lossy	B-Algorithm
data	I-Algorithm
compression	I-Algorithm
accurate	O
enough	O
that	O
the	O
compressed	O
result	O
is	O
perceptually	O
indistinguishable	O
from	O
the	O
uncompressed	B-General_Concept
input	O
,	O
i.e.	O
</s>
<s>
perceptually	B-Algorithm
lossless	I-Algorithm
.	O
</s>
<s>
A	O
transparency	B-Algorithm
threshold	I-Algorithm
is	O
a	O
given	O
value	O
at	O
which	O
transparency	B-Algorithm
is	O
reached	O
.	O
</s>
<s>
It	O
is	O
commonly	O
used	O
to	O
describe	O
compressed	B-General_Concept
data	I-General_Concept
bitrates	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
transparency	B-Algorithm
threshold	I-Algorithm
for	O
MP3	O
to	O
linear	B-Algorithm
PCM	I-Algorithm
audio	O
is	O
said	O
to	O
be	O
between	O
175	O
and	O
245kbit/s	O
,	O
at	O
44.1	O
kHz	O
,	O
when	O
encoded	O
as	O
VBR	O
MP3	O
(	O
corresponding	O
to	O
the	O
-V3	O
and	O
-V0	O
settings	O
of	O
the	O
highly	O
popular	O
LAME	B-Algorithm
MP3	O
encoder	O
)	O
.	O
</s>
<s>
This	O
means	O
that	O
when	O
an	O
MP3	O
that	O
was	O
encoded	O
at	O
those	O
bitrates	O
is	O
being	O
played	O
back	O
,	O
it	O
is	O
indistinguishable	O
from	O
the	O
original	O
PCM	B-Algorithm
,	O
and	O
the	O
compression	O
is	O
transparent	O
to	O
the	O
listener	O
.	O
</s>
<s>
The	O
term	O
transparent	O
compression	O
can	O
also	O
refer	O
to	O
a	O
filesystem	B-Application
feature	O
that	O
allows	O
compressed	O
files	O
to	O
be	O
read	O
and	O
written	O
just	O
like	O
regular	O
ones	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
the	O
compressor	O
is	O
typically	O
a	O
general-purpose	O
lossless	B-Algorithm
compressor	O
.	O
</s>
<s>
Transparency	B-Algorithm
,	O
like	O
sound	O
or	O
video	O
quality	O
,	O
is	O
subjective	O
.	O
</s>
<s>
It	O
depends	O
most	O
on	O
the	O
listener	O
's	O
familiarity	O
with	O
digital	O
artifacts	B-Algorithm
,	O
their	O
awareness	O
that	O
artifacts	B-Algorithm
may	O
in	O
fact	O
be	O
present	O
,	O
and	O
to	O
a	O
lesser	O
extent	O
,	O
the	O
compression	O
method	O
,	O
bit	O
rate	O
used	O
,	O
input	O
characteristics	O
,	O
and	O
the	O
listening/viewing	O
conditions	O
and	O
equipment	O
.	O
</s>
<s>
Judging	O
transparency	B-Algorithm
can	O
be	O
difficult	O
,	O
due	O
to	O
observer	O
bias	O
,	O
in	O
which	O
subjective	O
like/dislike	O
of	O
a	O
certain	O
compression	O
methodology	O
emotionally	O
influences	O
their	O
judgment	O
.	O
</s>
<s>
The	O
ABX	O
method	O
is	O
normally	O
used	O
,	O
with	O
a	O
null	B-General_Concept
hypothesis	I-General_Concept
that	O
the	O
samples	O
tested	O
are	O
the	O
same	O
and	O
with	O
an	O
alternative	B-General_Concept
hypothesis	I-General_Concept
that	O
the	O
samples	O
are	O
in	O
fact	O
different	O
.	O
</s>
<s>
All	O
lossless	B-Algorithm
data	I-Algorithm
compression	I-Algorithm
methods	O
are	O
transparent	O
,	O
by	O
nature	O
.	O
</s>
<s>
Both	O
the	O
DSC	O
in	O
DisplayPort	B-Protocol
and	O
the	O
default	O
settings	O
of	O
JPEG	O
XL	O
are	O
regarded	O
as	O
visually	B-Algorithm
lossless	I-Algorithm
.	O
</s>
<s>
This	O
test	O
is	O
more	O
sensitive	O
than	O
a	O
side-by-side	O
comparison	O
(	O
"	O
visually	O
almost	O
lossless	B-Algorithm
"	O
)	O
,	O
as	O
the	O
human	O
eye	O
is	O
highly	O
sensitive	O
to	O
temporal	O
changes	O
in	O
light	O
.	O
</s>
<s>
A	O
perceptually	B-Algorithm
lossless	I-Algorithm
compression	O
is	O
always	O
free	O
of	O
compression	B-Algorithm
artifacts	I-Algorithm
,	O
but	O
the	O
inverse	O
is	O
not	O
true	O
:	O
it	O
is	O
possible	O
for	O
a	O
compressor	O
to	O
produce	O
a	O
signal	O
that	O
appears	O
natural	O
but	O
with	O
altered	O
contents	O
.	O
</s>
<s>
Such	O
a	O
confusion	O
is	O
widely	O
present	O
in	O
the	O
field	O
of	O
radiology	O
(	O
specifically	O
for	O
the	O
study	O
of	O
diagnostically	B-Algorithm
acceptable	I-Algorithm
irreversible	I-Algorithm
compression	I-Algorithm
)	O
,	O
where	O
visually	B-Algorithm
lossless	I-Algorithm
is	O
taken	O
to	O
mean	O
anywhere	O
from	O
artifact-free	O
to	O
being	O
indistinguishable	O
on	O
a	O
side-to-side	O
view	O
,	O
neither	O
being	O
as	O
stringent	O
as	O
the	O
flicker	O
test	O
.	O
</s>
