<s>
709	O
,	O
also	O
known	O
as	O
Rec.709	B-Device
,	O
BT.709	B-Device
,	O
and	O
ITU	O
709	O
,	O
is	O
a	O
standard	O
developed	O
by	O
ITU-R	O
for	O
image	O
encoding	O
and	O
signal	O
characteristics	O
of	O
high-definition	B-Device
television	I-Device
.	O
</s>
<s>
The	O
most	O
recent	O
version	O
is	O
BT.709-6	O
released	O
in	O
2015	O
.	O
</s>
<s>
BT.709-6	O
defines	O
the	O
Picture	O
characteristics	O
as	O
having	O
a	O
(	O
widescreen	O
)	O
aspect	O
ratio	O
of	O
16:9	O
,	O
1080	O
active	O
lines	O
per	O
picture	O
,	O
1920	O
samples	O
per	O
line	O
,	O
and	O
a	O
square	O
pixel	O
aspect	O
ratio	O
.	O
</s>
<s>
The	O
first	O
version	O
of	O
the	O
standard	O
was	O
approved	O
by	O
the	O
CCIR	O
as	O
Rec.709	B-Device
in	O
1990	O
(	O
there	O
was	O
also	O
CCIR	O
Rec	O
.	O
</s>
<s>
XA/11	O
MOD	O
F	O
in	O
1989	O
)	O
,	O
with	O
the	O
stated	O
goal	O
of	O
a	O
worldwide	O
HDTV	B-Device
standard	O
.	O
</s>
<s>
The	O
ITU	O
superseded	O
the	O
CCIR	O
in	O
1992	O
,	O
and	O
subsequently	O
released	O
BT.709-1	O
in	O
November	O
1993	O
.	O
</s>
<s>
These	O
early	O
versions	O
still	O
left	O
many	O
unanswered	O
questions	O
,	O
and	O
the	O
lack	O
of	O
consensus	O
toward	O
a	O
worldwide	O
HDTV	B-Device
standard	O
was	O
evident	O
.	O
</s>
<s>
So	O
much	O
so	O
,	O
some	O
early	O
HDTV	B-Device
systems	O
such	O
as	O
1125/60	O
and	O
1250/50	O
were	O
still	O
a	O
part	O
of	O
the	O
standard	O
as	O
late	O
as	O
2002	O
in	O
BT.709-5	O
.	O
</s>
<s>
Previous	O
versions	O
of	O
BT.709	B-Device
included	O
legacy	O
systems	O
such	O
as	O
1035i30	O
and	O
1152i25	O
HDTV	B-Device
systems	O
.	O
</s>
<s>
These	O
are	O
now	O
obsolete	O
,	O
and	O
replaced	O
by	O
the	O
system	O
defined	O
in	O
the	O
2015	O
ITU	O
BT.709-6	O
.	O
</s>
<s>
BT.709	B-Device
offers	O
over	O
a	O
variety	O
of	O
frame	O
rates	O
and	O
scanning	O
schemes	O
,	O
which	O
along	O
with	O
separating	O
the	O
picture	O
size	O
from	O
frame	O
rate	O
has	O
provided	O
the	O
flexibility	O
for	O
BT.709	B-Device
to	O
become	O
the	O
worldwide	O
standard	O
for	O
HDTV	B-Device
.	O
</s>
<s>
BT.709-6	O
specifies	O
the	O
following	O
frame	O
rates	O
,	O
where	O
P	O
indicates	O
a	O
progressively	B-Device
scanned	I-Device
frame	I-Device
,	O
PsF	O
indicates	O
progressive	O
segmented	O
frames	O
,	O
and	O
I	O
indicates	O
interlaced	O
:	O
</s>
<s>
regions	O
that	O
formerly	O
used	O
50Hz	O
systems	O
such	O
as	O
PAL	B-Language
or	O
SECAM	O
.	O
</s>
<s>
There	O
are	O
no	O
fractional	O
rates	O
as	O
PAL	B-Language
and	O
SECAM	O
did	O
not	O
have	O
the	O
pull-down	O
issue	O
of	O
NTSC	O
.	O
</s>
<s>
Per	O
BT.709	B-Device
,	O
cameras	O
may	O
capture	O
in	O
either	O
progressive	O
or	O
interlaced	O
form	O
.	O
</s>
<s>
+RGB	O
color	B-Algorithm
space	I-Algorithm
parametersITU-R	O
Rec	O
.	O
</s>
<s>
Note	O
that	O
red	O
and	O
blue	O
and	O
yG	O
are	O
the	O
same	O
as	O
the	O
EBU	O
Tech	O
3213	O
(	O
PAL	B-Language
)	O
primaries	O
while	O
the	O
xG	O
is	O
halfway	O
between	O
EBU	O
Tech	O
3213	O
's	O
xG	O
and	O
SMPTE	O
C	O
's	O
xG	O
(	O
PAL	B-Language
and	O
NTSC	O
are	O
two	O
types	O
of	O
BT.601-6	O
)	O
.	O
</s>
<s>
In	O
coverage	O
of	O
the	O
CIE	O
1931	O
color	B-Algorithm
space	I-Algorithm
the	O
Rec.709	B-Device
color	B-Algorithm
space	I-Algorithm
(	O
and	O
the	O
derivative	O
sRGB	O
color	B-Algorithm
space	I-Algorithm
)	O
is	O
almost	O
identical	O
to	O
Rec	O
.	O
</s>
<s>
Rec.709	B-Device
specifies	O
a	O
non-linear	O
OETF	O
(	O
opto-electrical	B-Algorithm
transfer	I-Algorithm
function	I-Algorithm
)	O
which	O
is	O
known	O
as	O
the	O
"	O
camera	O
gamma	O
"	O
and	O
which	O
describes	O
how	O
HDTV	B-Device
camera	O
encodes	O
the	O
linear	O
scene	O
light	O
into	O
a	O
non-linear	O
electrical	O
signal	O
value	O
.	O
</s>
<s>
709	O
does	O
n't	O
specify	O
the	O
display	O
EOTF	B-Algorithm
(	O
electro-optical	B-Algorithm
transfer	I-Algorithm
function	I-Algorithm
)	O
which	O
describes	O
how	O
HDTV	B-Device
displays	O
should	O
convert	O
the	O
non-linear	O
electrical	O
signal	O
into	O
linear	O
displayed	O
light	O
,	O
that	O
was	O
done	O
in	O
ITU-R	B-Algorithm
BT.1886	I-Algorithm
.	O
</s>
<s>
Rec.709	B-Device
is	O
"	O
scene-referred	O
"	O
,	O
which	O
means	O
that	O
change	O
of	O
primaries	O
should	O
happen	O
on	O
scene	O
linear	O
light	O
(	O
by	O
applying	O
inverse	O
OETF	O
,	O
changing	O
primaries	O
and	O
applying	O
OETF	O
again	O
,	O
only	O
after	O
which	O
you	O
convert	O
to	O
display	O
linear	O
light	O
using	O
EOTF	B-Algorithm
)	O
.	O
</s>
<s>
Old	O
CRTs	O
had	O
a	O
EOTF	B-Algorithm
of	O
2.35	O
pure	O
gamma	O
and	O
thus	O
the	O
corresponding	O
correction	O
of	O
709	O
OETF	O
to	O
get	O
EOTF	B-Algorithm
linear	O
image	O
(	O
if	O
1.2	O
end-to-end	O
gamma	O
is	O
assumed	O
)	O
was	O
a	O
pure	O
gamma	O
of	O
1.2	O
/	O
2.35	O
=	O
0.51	O
=	O
1/1.9608	O
.	O
</s>
<s>
In	O
typical	O
production	O
practice	O
the	O
encoding	O
function	O
of	O
image	O
sources	O
(	O
OETF	O
)	O
is	O
adjusted	O
so	O
that	O
the	O
final	O
picture	O
has	O
the	O
desired	O
aesthetic	O
look	O
,	O
as	O
viewed	O
on	O
a	O
reference	O
monitor	O
with	O
a	O
gamma	O
of	O
2.4	O
(	O
per	O
ITU-R	B-Algorithm
BT.1886	I-Algorithm
)	O
in	O
a	O
dim	O
reference	O
viewing	O
environment	O
(	O
per	O
ITU-R	O
Rec	O
.	O
</s>
<s>
The	O
display	O
EOTF	B-Algorithm
of	O
HDTV	B-Device
(	O
sometimes	O
referred	O
as	O
the	O
"	O
display	O
gamma	O
"	O
)	O
,	O
is	O
not	O
the	O
inverse	O
of	O
the	O
camera	O
OETF	O
.	O
</s>
<s>
The	O
EOTF	B-Algorithm
is	O
not	O
specified	O
in	O
Rec	O
.	O
</s>
<s>
It	O
is	O
discussed	O
in	O
and	O
specified	O
in	O
ITU-R	B-Algorithm
BT.1886	I-Algorithm
as	O
an	O
equivalent	O
gamma	O
of	O
2.4	O
,	O
that	O
is	O
deviating	O
from	O
it	O
in	O
black	O
region	O
depending	O
on	O
how	O
deep	O
the	O
black	O
is	O
.	O
</s>
<s>
The	O
resulting	O
end-to-end	O
system	O
gamma	O
(	O
OOTF	B-Algorithm
)	O
of	O
HD	O
television	O
system	O
is	O
about	O
1.2	O
and	O
it	O
has	O
been	O
deliberately	O
designed	O
to	O
provide	O
compensation	O
for	O
the	O
dim	O
surround	O
effect	O
.	O
</s>
<s>
Rec.709	B-Device
and	O
sRGB	O
share	O
the	O
same	O
primary	O
chromaticities	O
and	O
white	O
point	O
chromaticity	O
;	O
however	O
,	O
sRGB	O
is	O
explicitly	O
output	O
(	O
display	O
)	O
referred	O
with	O
an	O
equivalent	O
gamma	O
of	O
2.2	O
(	O
the	O
actual	O
function	O
is	O
also	O
piecewise	O
to	O
avoid	O
near	O
black	O
issues	O
)	O
.	O
</s>
<s>
Display	O
P3	O
uses	O
sRGB	O
EOTF	B-Algorithm
with	O
its	O
linear	O
segment	O
,	O
a	O
change	O
of	O
that	O
segment	O
from	O
709	O
is	O
needed	O
by	O
either	O
using	O
parametric	O
curve	O
encoding	O
of	O
ICC	O
v4	O
or	O
by	O
using	O
slope	O
limit	O
.	O
</s>
<s>
Rec.709	B-Device
defines	O
an	O
R’G’B’	O
encoding	O
and	O
a	O
Y’CBCR	O
encoding	O
,	O
each	O
with	O
either	O
8	O
bits	O
or	O
10	O
bits	O
per	O
sample	O
in	O
each	O
color	O
channel	O
.	O
</s>
<s>
Rec.709	B-Device
'	O
s	O
10-bit	O
encoding	O
uses	O
nominal	O
values	O
four	O
times	O
those	O
of	O
the	O
8-bit	O
encoding	O
,	O
to	O
ease	O
the	O
conversion	O
it	O
uses	O
simple	O
padding	O
for	O
reference	O
values	O
,	O
for	O
example	O
240	O
is	O
just	O
padded	O
by	O
two	O
trailing	O
zeroes	O
and	O
gives	O
960	O
for	O
10	O
bit	O
maximum	O
chroma	O
.	O
</s>
<s>
Rec.709	B-Device
'	O
s	O
nominal	O
ranges	O
are	O
the	O
same	O
as	O
those	O
defined	O
in	O
ITU	O
Rec	O
.	O
</s>
<s>
While	O
BT.709	B-Device
has	O
eased	O
the	O
compatibility	O
issue	O
in	O
terms	O
of	O
the	O
consumer	O
and	O
television	O
set	O
manufacturer	O
,	O
broadcast	O
facilities	O
still	O
use	O
a	O
particular	O
frame	O
rate	O
based	O
on	O
region	O
,	O
such	O
as	O
29.97	O
in	O
North	O
America	O
,	O
or	O
25	O
in	O
Europe	O
meaning	O
that	O
broadcast	O
content	O
still	O
requires	O
at	O
least	O
frame	O
rate	O
conversion	O
.	O
</s>
<s>
The	O
vast	O
legacy	O
library	O
of	O
standard-definition	B-Device
programs	O
and	O
content	O
presents	O
further	O
challenges	O
.	O
</s>
<s>
NTSC	O
,	O
PAL	B-Language
,	O
and	O
SECAM	O
are	O
all	O
interlaced	O
formats	O
in	O
a	O
4:3	O
aspect	O
ratio	O
,	O
and	O
at	O
a	O
relatively	O
low	O
resolution	O
.	O
</s>
<s>
The	O
solution	O
is	O
to	O
either	O
up-convert	O
only	O
to	O
an	O
interlaced	O
BT.709	B-Device
format	O
at	O
the	O
same	O
field	O
rate	O
,	O
and	O
scale	O
the	O
fields	O
independently	O
,	O
or	O
use	O
motion	O
processing	O
to	O
remove	O
the	O
inter-field	O
motion	O
and	O
deinterlace	O
,	O
creating	O
progressive	O
frames	O
.	O
</s>
<s>
Cropping	O
the	O
top	O
and/or	O
bottom	O
of	O
the	O
standard-definition	B-Device
frame	O
may	O
or	O
may	O
not	O
work	O
,	O
depending	O
on	O
if	O
the	O
composition	O
allows	O
it	O
and	O
if	O
there	O
are	O
graphics	O
or	O
titles	O
that	O
would	O
be	O
cut	O
off	O
.	O
</s>
<s>
In	O
addition	O
,	O
the	O
SMPTE	O
C	O
RGB	O
primaries	O
used	O
in	O
North	O
American	O
standard	B-Device
definition	I-Device
are	O
different	O
than	O
those	O
of	O
BT.709	B-Device
(	O
SMPTE	O
C	O
is	O
commonly	O
referred	O
to	O
as	O
NTSC	O
,	O
however	O
it	O
is	O
a	O
different	O
set	O
of	O
primaries	O
and	O
a	O
different	O
white	O
point	O
than	O
the	O
1953	O
NTSC	O
)	O
.	O
</s>
<s>
The	O
red	O
and	O
blue	O
primaries	O
for	O
PAL	B-Language
and	O
SECAM	O
are	O
the	O
same	O
as	O
BT.709	B-Device
,	O
with	O
a	O
change	O
in	O
the	O
green	O
primary	O
.	O
</s>
<s>
Converting	O
the	O
image	O
precisely	O
requires	O
a	O
LUT	O
(	O
lookup	O
table	O
)	O
or	O
a	O
color	O
managed	O
workflow	O
to	O
convert	O
the	O
colors	O
to	O
the	O
new	O
colorspace	B-Algorithm
.	O
</s>
<s>
However	O
in	O
practice	O
this	O
is	O
often	O
ignored	O
,	O
except	O
in	O
mpv	O
,	O
because	O
even	O
if	O
the	O
player	O
is	O
color	O
managed	O
(	O
most	O
of	O
them	O
are	O
not	O
,	O
including	O
VLC	O
)	O
,	O
it	O
can	O
only	O
see	O
BT.709	B-Device
or	O
BT.2020	O
primaries	O
only	O
.	O
</s>
<s>
When	O
encoding	O
Y’CBCR	O
video	O
,	O
BT.709	B-Device
creates	O
gamma-encoded	O
luma	O
(	O
Y’	O
)	O
using	O
matrix	O
coefficients	O
0.2126	O
,	O
0.7152	O
,	O
and	O
0.0722	O
(	O
together	O
they	O
add	O
to1	O
)	O
.	O
</s>
<s>
BT.709-1	O
used	O
slightly	O
different	O
0.2125	O
,	O
0.7154	O
,	O
0.0721	O
(	O
changed	O
to	O
standard	O
ones	O
in	O
BT.709-2	O
)	O
.	O
</s>
<s>
Although	O
worldwide	O
agreement	O
on	O
asingle	O
R’G’B’	O
system	O
was	O
achieved	O
with	O
Rec.709	B-Device
,	O
adoption	O
of	O
different	O
luma	O
coefficients	O
(	O
as	O
those	O
are	O
derived	O
from	O
primaries	O
and	O
white	O
point	O
)	O
for	O
Y’CBCR	O
requires	O
the	O
use	O
of	O
different	O
luma-chroma	O
decoding	O
for	O
standard	B-Device
definition	I-Device
and	O
high	O
definition	O
.	O
</s>
<s>
These	O
projects	O
can	O
re-telecine	O
their	O
cut	O
negative	O
masters	O
to	O
a	O
BT.709	B-Device
master	O
at	O
a	O
reasonable	O
cost	O
,	O
and	O
gain	O
the	O
benefit	O
of	O
the	O
full	O
resolution	O
of	O
film	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
for	O
projects	O
that	O
originated	O
on	O
film	O
,	O
but	O
completed	O
their	O
online	O
master	O
using	O
video	O
online	O
methods	O
would	O
need	O
to	O
re-telecine	O
the	O
individual	O
needed	O
film	O
takes	O
and	O
then	O
re-assemble	O
,	O
a	O
significantly	O
greater	O
amount	O
of	O
labor	O
and	O
machine	O
time	O
is	O
required	O
in	O
this	O
case	O
,	O
versus	O
a	O
telecine	B-Application
for	O
a	O
conformed	O
negative	O
.	O
</s>
<s>
sRGB	O
was	O
created	O
after	O
the	O
early	O
development	O
of	O
Rec.709	B-Device
.	O
</s>
<s>
The	O
creators	O
of	O
sRGB	O
chose	O
to	O
use	O
the	O
same	O
primaries	O
and	O
white	O
point	O
as	O
Rec.709	B-Device
,	O
but	O
changed	O
the	O
tone	O
response	O
curve	O
(	O
sometimes	O
referred	O
to	O
as	O
gamma	O
)	O
to	O
better	O
suit	O
the	O
intended	O
use	O
in	O
offices	O
and	O
brighter	O
conditions	O
than	O
television	O
viewing	O
in	O
a	O
dark	O
living	O
room	O
.	O
</s>
