<s>
ICTCP	B-Device
,	O
ICtCp	B-Device
,	O
or	O
ITP	O
is	O
a	O
color	O
representation	O
format	O
specified	O
in	O
the	O
Rec	O
.	O
</s>
<s>
ITU-R	B-Device
BT.2100	I-Device
standard	O
that	O
is	O
used	O
as	O
a	O
part	O
of	O
the	O
color	B-Algorithm
image	I-Algorithm
pipeline	I-Algorithm
in	O
video	O
and	O
digital	B-Application
photography	I-Application
systems	O
for	O
high	B-General_Concept
dynamic	I-General_Concept
range	I-General_Concept
(	O
HDR	O
)	O
and	O
wide	O
color	O
gamut	O
(	O
WCG	O
)	O
imagery	O
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
Dolby	O
Laboratories	O
from	O
the	O
IPT	O
color	B-Algorithm
space	I-Algorithm
by	O
Ebner	O
and	O
Fairchild	O
.	O
</s>
<s>
The	O
format	O
is	O
derived	O
from	O
an	O
associated	O
RGB	O
color	B-Algorithm
space	I-Algorithm
by	O
a	O
coordinate	O
transformation	O
that	O
includes	O
two	O
matrix	O
transformations	O
and	O
an	O
intermediate	O
nonlinear	O
transfer	O
function	O
that	O
is	O
informally	O
known	O
as	O
gamma	O
pre-correction	O
.	O
</s>
<s>
The	O
ICTCP	B-Device
transformation	O
can	O
be	O
used	O
with	O
RGB	O
signals	O
derived	O
from	O
either	O
the	O
perceptual	B-Algorithm
quantizer	I-Algorithm
(	O
PQ	B-Algorithm
)	O
or	O
hybrid	O
log	O
–	O
gamma	O
(	O
HLG	B-Algorithm
)	O
nonlinearity	O
functions	O
,	O
but	O
is	O
most	O
commonly	O
associated	O
with	O
the	O
PQ	B-Algorithm
function	O
(	O
which	O
was	O
also	O
developed	O
by	O
Dolby	O
)	O
.	O
</s>
<s>
The	O
ICTCP	B-Device
color	O
representation	O
scheme	O
is	O
conceptually	O
related	O
to	O
the	O
LMS	O
color	B-Algorithm
space	I-Algorithm
,	O
as	O
the	O
color	O
transformation	O
from	O
RGB	O
to	O
ICTCP	B-Device
is	O
defined	O
by	O
first	O
converting	O
RGB	O
to	O
LMS	O
with	O
a	O
3×3	O
matrix	O
transformation	O
,	O
then	O
applying	O
the	O
nonlinearity	O
function	O
,	O
and	O
then	O
converting	O
the	O
nonlinear	O
signals	O
to	O
ICTCP	B-Device
using	O
another	O
3×3	O
matrix	O
transformation	O
.	O
</s>
<s>
ICTCP	B-Device
was	O
defined	O
as	O
YCC	O
digital	O
format	O
with	O
support	O
for	O
4:4:4	O
,	O
4:2:2	O
and	O
4:2:0	O
chroma	O
subsampling	O
in	O
CTA-861-H	O
(	O
that	O
means	O
that	O
in	O
limited	O
range	O
10	O
bit	O
mode	O
0	O
,	O
1	O
,	O
2	O
,	O
3	O
,	O
1020	O
,	O
1021	O
,	O
1022	O
,	O
1023	O
values	O
are	O
reserved	O
)	O
.	O
</s>
<s>
ICTCP	B-Device
is	O
defined	O
by	O
Rec	O
.	O
</s>
<s>
Calculate	O
LMS	O
from	O
BT.2100	B-Device
RGB	O
:	O
</s>
<s>
If	O
the	O
PQ	B-Algorithm
transfer	I-Algorithm
function	I-Algorithm
is	O
used	O
:	O
</s>
<s>
If	O
the	O
HLG	B-Algorithm
transfer	O
function	O
is	O
used	O
:	O
</s>
<s>
Calculate	O
ICTCP	B-Device
:	O
</s>
<s>
for	O
PQ	B-Algorithm
:	O
</s>
<s>
for	O
HLG	B-Algorithm
:	O
</s>
<s>
The	O
HLG	B-Algorithm
matrix	O
can	O
be	O
derived	O
the	O
same	O
way	O
as	O
the	O
PQ	B-Algorithm
matrix	O
,	O
with	O
the	O
only	O
difference	O
being	O
the	O
scaling	O
of	O
the	O
chroma	O
rows	O
.	O
</s>
<s>
The	O
inverted	O
decoding	O
ICTCP	B-Device
matrixes	O
are	O
specified	O
in	O
ITU-T	O
Series	O
H	O
Supplement	O
18	O
.	O
</s>
<s>
ICTCP	B-Device
is	O
defined	O
such	O
that	O
the	O
entire	O
BT.2020	O
space	O
fits	O
into	O
the	O
range	O
[	O
0	O
,	O
1 ]	O
for	O
I	O
and	O
[	O
-0.5	O
,	O
+	O
0.5	O
]	O
for	O
the	O
two	O
chroma	O
components	O
.	O
</s>
<s>
The	O
related	O
uniform	O
color	B-Algorithm
space	I-Algorithm
ITP	O
used	O
in	O
ΔEITP	O
(	O
Rec	O
.	O
</s>
<s>
There	O
is	O
support	O
for	O
ICtCp	B-Device
in	O
zimg	O
(	O
including	O
zimg	O
as	O
part	O
of	O
FFmpeg	O
)	O
and	O
color-science	O
,	O
for	O
both	O
HLG	B-Algorithm
and	O
PQ	B-Algorithm
.	O
</s>
<s>
The	O
preceder	O
to	O
ICTCP	B-Device
,	O
Ebner	O
&	O
Fairchild	O
IPT	O
color	O
appearance	O
model	O
(	O
1998	O
)	O
,	O
has	O
a	O
mostly	O
similar	O
transformation	O
pipeline	O
of	O
input	O
LMS	O
nonlinearity	O
IPT	O
.	O
</s>
<s>
The	O
differences	O
are	O
that	O
it	O
defines	O
its	O
input	O
to	O
the	O
more	O
general	O
CIEXYZ	O
tristimulus	O
color	B-Algorithm
space	I-Algorithm
and	O
as	O
a	O
result	O
has	O
a	O
more	O
conventional	O
Hunt-Pointer-Estevez	O
(	O
for	O
D65	O
)	O
matrix	O
for	O
LMS	O
.	O
</s>
<s>
The	O
second	O
matrix	O
here	O
is	O
slightly	O
different	O
from	O
the	O
ICTCP	B-Device
matrix	O
,	O
mainly	O
in	O
that	O
is	O
also	O
considers	O
S	O
(	O
blue	O
cone	O
)	O
for	O
intensity	O
,	O
but	O
ICTCP	B-Device
has	O
also	O
Rotation	O
matrix	O
(	O
to	O
align	O
skin	O
tones	O
)	O
and	O
Scalar	O
matrix	O
(	O
scaled	O
to	O
fit	O
the	O
full	O
BT.2020	O
gamut	O
inside	O
the	O
-0.5	O
to	O
0.5	O
region	O
)	O
multiplied	O
with	O
this	O
matrix	O
:	O
</s>
<s>
IPTPQc2	O
is	O
another	O
related	O
colorspace	B-Algorithm
used	O
by	O
Dolby	B-Device
Vision	I-Device
profile	O
5	O
BL+RPU	O
(	O
without	O
EL	O
)	O
.	O
</s>
<s>
Documentation	O
on	O
this	O
format	O
is	O
scarce	O
due	O
to	O
its	O
proprietary	O
nature	O
,	O
but	O
a	O
patent	O
on	O
the	O
"	O
IPT-PQ	O
"	O
(	O
perceptually	O
quantized	O
IPT	O
)	O
color	B-Algorithm
space	I-Algorithm
The	O
matrix	O
is	O
as	O
follows	O
:	O
</s>
<s>
It	O
is	O
used	O
by	O
Disney+	B-Application
,	O
Apple	O
TV+	O
and	O
Netflix	O
.	O
</s>
<s>
Support	O
for	O
decoding	O
all	O
stages	O
was	O
added	O
in	O
mpv	B-Language
.	O
</s>
<s>
ICTCP	B-Device
has	O
near	O
constant	O
luminance	O
,	O
which	O
improves	O
chroma	O
subsampling	O
versus	O
YCBCR	O
.	O
</s>
<s>
ICTCP	B-Device
also	O
improves	O
hue	O
linearity	O
compared	O
with	O
YCBCR	O
,	O
which	O
helps	O
with	O
compression	O
performance	O
and	O
color	O
volume	O
mapping	O
.	O
</s>
<s>
When	O
combined	O
with	O
adaptive	O
reshaping	O
ICTCP	B-Device
can	O
improve	O
compression	O
performance	O
by	O
10%	O
.	O
</s>
<s>
For	O
CIEDE2000	O
color	O
quantization	O
errors	O
,	O
10-bit	O
ICTCP	B-Device
would	O
be	O
equivalent	O
to	O
11.5	O
bit	O
YCBCR	O
,	O
that	O
is	O
why	O
ΔEITP	O
standard	O
was	O
introduced	O
as	O
ITU-R	O
Rec	O
.	O
</s>
<s>
Luminance	O
constancy	O
is	O
improved	O
with	O
ICTCP	B-Device
,	O
which	O
has	O
a	O
luminance	O
relationship	O
of	O
0.998	O
between	O
the	O
luma	O
and	O
encoded	O
brightness	O
while	O
YCBCR	O
has	O
a	O
luminance	O
relationship	O
of	O
0.819	O
.	O
</s>
<s>
ICTCP	B-Device
is	O
supported	O
in	O
the	O
HEVC	B-Algorithm
video	O
coding	O
standard	O
.	O
</s>
<s>
It	O
is	O
also	O
a	O
digital	O
YCC	O
format	O
and	O
can	O
be	O
signaled	O
in	O
EDID	B-General_Concept
's	O
Colorimetry	O
block	O
as	O
part	O
of	O
CTA-861-H	O
.	O
</s>
