Digital Cinema Initiatives, LLC (DCI) is the author and creator of this specification for the purpose of copyright and other laws in all countries throughout the world. The DCI copyright notice must be included in all reproductions, whether in whole or in part, and may not be deleted or attributed to others. DCI hereby grants to its members and their suppliers a limited license to reproduce this specification for their own use, provided it is not sold. Others should obtain permission to reproduce this specification from Digital Cinema Initiatives, LLC.
This document is a specification developed and adopted by Digital Cinema Initiatives, LLC. This document may be revised by DCI. It is intended solely as a guide for companies interested in developing products, which can be compatible with other products, developed using this document. Each DCI member company shall decide independently the extent to which it will utilize, or require adherence to, these specifications. DCI shall not be liable for any exemplary, incidental, proximate or consequential damages or expenses arising from the use of this document. This document defines only one approach to compatibility, and other approaches may be available to the industry.
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With the publication by Digital Cinema Initiatives, LLC, (DCI) of version 1.0 of the Digital Cinema System Specification in July 2005, DCI recognized that digital cinema had the potential to significantly improve the movie-going experience for the public. In the years since version 1.0, technological developments and innovation have realized that potential in many areas of picture and sound reproduction. Now, further advances in High Dynamic Range (HDR) technology in both reflective projectors and direct view displays offer new opportunities to enhance the theatrical motion picture experience.
DCI believes that these new HDR opportunities require a rational, empirical basis for setting image parameters. To this end, DCI has conducted extensive image testing, employing both lay and expert viewers. The requirements in this addendum are the considered results of these investigations, specified for both reflective and direct view image devices. The DCI member companies believe that their utilization will provide real and achievable benefits to theater audiences, theater owners, filmmakers and distributors.
The proper presentation of a High Dynamic Range Digital Cinema Distribution Master (HDR-DCDM) requires the definition of an HDR Reference Display and controlled environment. This specification defines the HDR Reference Display and specifies the tolerances around the critical image parameters for Review Rooms and Exhibition Theaters so that consistent and repeatable image quality can be achieved.
This specification defines the HDR Reference Display and its controlled environment, along with the acceptable tolerances around critical image parameters for Review Room and Exhibition Theater applications. The HDR Reference Display may be an HDR projection system or a direct view display.
The goal is to provide a means for achieving consistent and repeatable color image quality. The HDR Reference Display is a practical device. The nominal parameters are based on industry experience and have been demonstrated by commercially available HDR displays in controlled environments. Two levels of tolerances are specified, a tighter tolerance for Review Rooms where critical color judgments are made, and a wider tolerance for satisfactory reproduction in Exhibition Theaters used for general public viewing. (The use of the term βReview Roomβ includes the mastering environment where creative color decisions are made on a displayed image.)
This document shall be integrated into DCIβs Digital Cinema System Specification.
The names of standards publications and protocols are placed in [bracketed text]. International and industry standards contain provisions which, through reference in this text, constitute provisions of this specification. The most recent editions of the referenced standards shall be valid unless otherwise exempted in this specification. These referenced standards are subject to revision, and parties to agreements based upon this specification are encouraged to investigate the possibility of applying the most recent edition of the referenced standards.
For the purposes of this document, the following terms and definitions apply.
The smallest unit of d-cinema content that can be successfully edited while maintaining the integrity of the content. The edit unit value shall be an integer multiple of the duration of a single d-cinema frame. In most cases, the edit unit value is the same as the frame duration, but in certain applications, the value can be >1 (for example, stereoscopic d-cinema requires an edit unit value twice that of the frame duration).
The Minimum Active Black Level of an HDR Reference Display is the lowest luminance level above code value 0 reproduced within the specified uniformity tolerance.
The double prime notation (e.g., Xβ³) is used to indicate a value encoded using the [SMPTE ST 2084] Electro-Optical Transfer Function (EOTF).
The HDR Digital Cinema Distribution Master (HDR-DCDM) is a [SMPTE ST 428-1] DCDM that contains images and subtitles that are graded to be played on an HDR playback system, adhering to an EOTF complying with [SMPTE ST 2084] .
The HDR Digital Cinema Package (HDR-DCP) is a DCP that is made from the HDR-DCDM. When unpackaged, decrypted and decoded, the image is visually indistinguishable from the original HDR-DCDM image.
The
HDR
Reference
Display
shall
support
the
HDR-DCDM,
with
full-range
12
bit
image
data
formatted
for
[SMPTE
ST
2084]
EOTF
with
[ISO/CIE
11664]
[ISO
11664-3]
XYZ
colorimetry
at
2048x1080
or
4096x2160
image
structures
and
frame
rates
as
described
in
Table
1.
HDR content shall be identified by the presence of an HDR flag in both [SMPTE ST 377:2004] MXF and CPL metadata, which indicates that the EOTF is [SMPTE ST 2084] .
For
MXF
picture
track
files
that
carry
HDR
essence,
this
fact
shall
be
signaled
using
the
"Transfer
Characteristic"
Transfer
Characteristic
property
of
the
MXF
"Generic
Generic
Picture
Essence
Descriptor"
Descriptor
to
indicate
the
EOTF
is
[SMPTE
ST
2084]
.
The
UL
value
to
be
used
shall
be
06.0E.2B.34.04.01.01.0D.04.01.01.01.01.0A.00.00
.
Composition
Playlists
containing
picture
track
files
that
carry
HDR
essence
shall
signal
this
fact
using
[SMTPE
[SMPTE
ST
429-16]
Metadata
as
follows:
described
in
Table
1
:
Scope: |
http://www.dcimovies.com/schemas/2018/HDR-Metadata
|
---|---|
Name: |
Image
Encoding
Parameters
|
Property Name: |
EOTF
|
Property Value: |
ST
2084
|
Below is an example excerpt from such a Composition:
<ExtensionMetadata scope="http://www.dcimovies.com/schemas/2018/HDR-Metadata"> <Name>Image Encoding Parameters</Name> <PropertyList> <Property> <Name>EOTF</Name> <Value>ST 2084</Value> </Property> </PropertyList> </ExtensionMetadata>
Devices shall display content in HDR mode when presented with a Composition Playlist and MXF Transfer Characteristic containing the signaling specified in Section 5.1 .
The
HDR
Reference
Display
shall
support
the
content
frame
rates
in
Table
1
2
,
expressed
in
Edit
Units
per
second:
Edit Unit/Sec. | 2K 2D | 2K 3D | 4K 2D |
---|---|---|---|
24 | Required | Required | Required |
48 | Required | Required | Required |
60 | Required | Required | Required |
96 | Required | ||
120 | Required |
Support
for
HDR
stereoscopic
presentations
is
optional;
βRequiredβ
in
the
2K
3D
category
of
Table
1
2
applies
only
to
displays
in
which
HDR
stereoscopic
exhibition
is
implemented.
Stereoscopic HDR implementations have yet to be sufficiently demonstrated to DCI. Therefore, parameters for stereoscopic HDR are reserved for this specification. Additional requirements for stereographic HDR may be specified by DCI in a future specification.
An HDR system in SDR Mode shall display SDR content in a manner that emulates the SDR display on which the content was mastered, including to [SMPTE ST 431-1] . An HDR system in SDR Mode shall not reproduce screen black level values lower than 0.01 cd/m 2 . In SDR Mode, the grayscale tracking shall conform to [SMPTE RP 431-2] , with the exception that screen black level shall only be displayed at luminance levels at or above 0.01 cd/m 2 .
The display shall be turned on and allowed to thermally stabilize for 20 to 30 minutes prior to all measurements. The room lights shall be turned off, except for the minimal lighting provided for working or safety reasons.
The display shall be calibrated to the target image parameters before final measurements are made.
An HDR Reference Display can be either a reflective projector or a direct view display. Stray light reflected from the screen or display should be minimized. Black, non-reflective finishes on all surfaces, along with recessed lighting, should be used.
With
the
device
turned
off,
measure
the
luminance
of
the
center
of
the
screen.
For
both
Review
Rooms
and
Exhibition
Theaters,
the
ambient
light
level
measured
in
the
center
of
the
screen
should
be
less
than
or
equal
to
0.005
0.002
cd/m
2
for
reflective
projector
screens
and
less
than
or
equal
to
0.0002
cd/m
2
for
direct
view
displays.
A
lab
environment
used
for
device
testing
should
have
all
ambient
light
eliminated
such
that
reflected
light
on
screen
is
less
than
0.0005
cd/m
2
.
Safety
regulations
and
the
placement
of
exit
lights
or
access
lights
may
result
in
a
higher
ambient
light
level,
but
it
should
be
noted
that
this
will
reduce
the
contrast
of
the
resulting
image.
The reference viewing position for color grading shall be at a viewing distance of 1.5 to 3.5 screen heights (for constant height presentation), or if constant width is used for both 2.39:1 and 1.85:1 aspect ratios, then this viewing distance refers to the height of the 1.85:1 picture. Lighting on work surfaces or consoles should be masked and filtered to eliminate any spill onto the display.
All image parameters shall be measured as light from the screen or display, with the measurements made from the reference viewing position in the Review Room, or from the center of the normal seating area in an Exhibition Theater.
The
variance
in
the
measured
luminance
from
the
center
to
the
sides
and
corners
of
the
screen
or
display
shall
not
exceed
the
specified
tolerances
in
Table
2
3
as
measured
per
[SMPTE
RP
431-2]
.
When
the
HDR
Reference
Display
is
sent
a
full
frame
image
with
the
code
values
2060
Xβ³,
2081
Yβ³,
2116
Zβ³,
the
chromaticity
coordinates
of
the
displayed
image
shall
be
x
=
0.3127,
y
=
0.3291.
These
code
values
shall
produce
a
displayed
luminance
of
100.1
cd/m
2
within
the
specified
tolerances
in
Table
2
3
.
When
the
HDR
Reference
Display
is
sent
a
full
frame
image
with
code
values
2524
Xβ³,
2546
Yβ³,
2583
Zβ³,
the
chromaticity
coordinates
of
the
displayed
image
shall
be
x
=
0.3128,
y
=
0.3290.
These
code
values
shall
produce
a
displayed
luminance
of
299.6
cd/m
2
within
the
specified
tolerances
in
Table
2
3
.
Behavior of code values representing output luminance exceeding 299.6 cd/m 2 is undefined.
Other
creative
white
points
are
possible
and
can
be
accommodated,
albeit
with
some
marginal
differences
in
peak
luminance.
Refer
to
Table
5
6
for
examples
of
alternative
creative
white
points.
In the event that display or projection technology is developed that is able to meet all provisions of this specification (e.g., peak luminance, screen black level, etc.) but is unable to meet the full-screen luminance requirements stated in this section, DCI leaves open the possibility of developing a new application profile to accommodate such technology.
Minimum
Active
Black
Level
shall
be
0.005
cd/m
2
and
shall
not
exceed
the
specified
tolerances
in
Table
2
3
.
Behavior
of
code
values
representing
output
luminance
below
0.005
cd/m
2
but
greater
than
zero
is
undefined.
When
the
HDR
Reference
Display
is
sent
a
full
frame
images
with
the
code
values
60
Xβ³,
62
Yβ³,
65
Zβ³,
the
chromaticity
coordinates
of
the
displayed
image
shall
be
x
=
0.3095,
y
=
0.3296.
These
code
values
shall
produce
a
displayed
luminance
of
0.005
cd/m
2
within
the
specified
tolerances
in
Table
2
3
.
Minimum active black level shall be measured in a manner that minimizes or eliminates the contribution of ambient light.
The
variance
in
displayed
chromaticity
across
the
display
shall
not
exceed
the
specified
tolerances
in
Table
2
3
.
The
encoding
transfer
function
shall
be
defined
in
terms
of
output-referred
[ISO
11664]
11664-3]
XYZ
tristimulus
values
produced
by
the
HDR
Reference
Display
unit.
The
HDR
transfer
functions
are
specified
using
12bit
[SMPTE
ST
2084]
XYZ
Encoding
Primaries
and
[SMPTE
ST
2084]
EOTF,
as
shown
below:.
below:
where:
and
the
unary
function
If the data is transported over certain interfaces (like Serial Digital Interface), code values 0-15 and 4080-4095 are reserved (illegal) code values and these code values will be clipped (see [SMPTE ST 372] ).
The following equations can be used to compute X, Y and Z from a set of code values:
EOTF
tracking
performance
shall
be
measured
at
the
code-values
described
in
Table
3
4
and
Table
4
5
with
the
tolerances
identified
in
Table
2
3
.
All measurements shall be made in the center of the Screen while in a lab environment such that no contamination from ambient light contributes to the output luminance.
The
HDR
color
volume
is
a
cuboid
with
vertices
determined
by
the
XYZ
coordinates
of
the
three
color
primaries,
the
white
point,
and
the
black
point.
The
color
primaries
and
white
point
in
Table
2
3
define
the
minimum
color
volume
for
an
HDR
Reference
Display.
Within
the
minimum
color
volume,
all
colors
shall
be
accurately
reproduced.
Table
2
3
defines
tolerances
for
the
color
primaries
of
the
minimum
color
volume.
Table
5
6
provides
exact
chromaticity
and
luminance
values
for
a
set
of
test
code
values
that
fall
within
these
tolerances.
All measurements shall be made in the center of the Screen while in a lab environment such that no contamination from ambient light contributes to the output luminance.
The
HDR
Reference
Display
image
parameters
and
tolerances
for
the
displayed
image
in
Review
Rooms
and
Exhibition
Theaters,
as
measured
from
the
display
or
screen,
and
including
the
room
ambient
light,
are
summarized
in
Table
2
3
.
Where
the
nominal
parameters
are
specified
as
minimums,
it
is
understood
that
these
parameters
shall
not
be
constrained
from
future
improvements
as
the
technology
progresses.
Tolerances for Electro-Optical Transfer Function distortion (measured as a percentage error) are calculated as follows:
Percentage error = 100*((measured luminance - target luminance) / target luminance)
where
target
luminance
is
derived
by
decoding
the
input
code
value
using
the
decoding
equation
in
Section
9.5.2
,
using
the
ranges
and
tolerances
specified
in
Table
2
3
.
|
Parameter | Nominal | HDR Reference Projector | HDR Direct View Display | ||
---|---|---|---|---|---|---|
Review Room Tolerance | Exhibition Theater Tolerance | Review Room Tolerance | Exhibition Theater Tolerance | |||
|
Luminance, center, Peak Luminance, White-1 D65 |
299.6
cd/m
2
|
Β± 18.0 cd/m 2 | Β± 30.0 cd/m 2 | Β± 9.0 cd/m 2 | Β± 9.0 cd/m 2 |
Luminance, Screen Average, White-1 D65 |
299.6
cd/m
2
|
N/A | N/A | Β± 9.0 cd/m 2 | Β± 9.0 cd/m 2 | |
Luminance, sides |
299.6
cd/m
2
|
85% to 100% of center | 75% to 100% of center | Β± 9.0 cd/m 2 | Β± 9.0 cd/m 2 | |
Luminance, corners |
299.6
cd/m
2
|
85% to 100% of center | Not Specified | Β± 9.0 cd/m 2 | Β± 9.0 cd/m 2 | |
Section 9.3 | Minimum Active Black Level |
0.005
cd/m
2
|
Β± 0.001 cd/m 2 | Β± 0.001 cd/m 2 | Β± 0.001 cd/m 2 | Β± 0.001 cd/m 2 |
Section 9.4 | White chromaticity, center, Peak Luminance, White-1 D65 |
x
=
0.3127
y = 0.3290 |
Β±
0.002
x
Β± 0.002 y |
Β±
0.006
x
Β± 0.006 y |
Β±
0.002
x
Β± 0.002 y |
Β±
0.006
x
Β± 0.006 y |
White chromaticity uniformity, corners (tolerance from center) |
Β±
0.000
x
Β± 0.000 y |
Β±
0.008
x
Β± 0.008 y |
Β±
0.015
x
Β± 0.015 y |
Β±
0.008
x
Β± 0.008 y |
Β±
0.015
x
Β± 0.015 y |
|
Section 9.5 | Electro-Optical Transfer Function | Per [SMPTE ST 2084] | Yβ¦0.02 cd/m 2 Β± 20%; 0.02<Yβ¦1.0 cd/m 2 Β± 5%; 1.0<Yβ¦299.6 cd/m 2 Β± 3% | Yβ¦0.02 cd/m 2 Β± 20%; 0.02<Yβ¦1.0 cd/m 2 Β± 5%; 1.0<Yβ¦299.6 cd/m 2 Β± 3% | Yβ¦0.02 cd/m 2 Β± 20%; 0.02<Yβ¦1.0 cd/m 2 Β± 5%; 1.0<Yβ¦299.6 cd/m 2 Β± 3% | Yβ¦0.02 cd/m 2 Β± 20%; 0.02<Yβ¦1.0 cd/m 2 Β± 5%; 1.0<Yβ¦299.6 cd/m 2 Β± 3% |
Section 9.6 | Color Volume | Volume in XYZ space defined by the black point & the following points expressed in (Y,x,y), representing a 299.6 nits P3D65 color volume: Red (68.69, 0.6800, 0.3200), Green (207.52, 0.2650, 0.6900), Blue (23.79, 0.1500, 0.0600), Peak White (299.6, 0.3127, 0.3290) | N/A | N/A | N/A | N/A |
Section 9.7 | Color Accuracy | The following points are expressed in (x,y): Red (0.6800, 0.3200), Green (0.2650, 0.6900), Blue (0.1500, 0.0600) | Red (0.6800 Β± .01, 0.3200 Β± .01), Green (0.2650 Β± .02, 0.6900 Β± .02), Blue (0.1500 + 0.01/- 0.03, 0.0600 + 0.02/- 0.04) | Red (0.6800 Β± .01, 0.3200 Β± .01), Green (0.2650 Β± .02, 0.6900 Β± .02), Blue (0.1500 + 0.01/- 0.03, 0.0600 + 0.02/- 0.04) | Red (0.6800 Β± .01, 0.3200 Β± .01), Green (0.2650 Β± .02, 0.6900 Β± .02), Blue (0.1500 + 0.01/- 0.03, 0.0600 + 0.02/- 0.04) | Red (0.6800 Β± .01, 0.3200 Β± .01), Green (0.2650 Β± .02, 0.6900 Β± .02), Blue (0.1500 + 0.01/- 0.03, 0.0600 + 0.02/- 0.04) |
Input Code Values | Output XYZ Tristimulus | Output Chromaticity Coordinates | Output Luminance | ||||||
---|---|---|---|---|---|---|---|---|---|
Step Number | Xβ³ | Yβ³ | Zβ³ | X | Y | Z | x | y | Y, cd/m 2 |
1 | 472 | 481 | 496 | 0.4748 | 0.5000 | 0.5441 | 0.3126 | 0.3292 | 0.50 |
2 | 603 | 614 | 632 | 0.9482 | 0.9999 | 1.0890 | 0.3122 | 0.3292 | 1.00 |
3 | 758 | 771 | 792 | 1.8977 | 2.0024 | 2.1811 | 0.3121 | 0.3293 | 2.00 |
4 | 1000 | 1015 | 1040 | 4.7475 | 5.0011 | 5.4488 | 0.3124 | 0.3291 | 5.00 |
5 | 1211 | 1227 | 1255 | 9.5069 | 9.9917 | 10.8912 | 0.3128 | 0.3288 |
|
6 | 1444 | 1462 | 1492 | 19.0069 | 20.0019 | 21.7626 | 0.3128 | 0.3291 | 20.00 |
7 | 1783 | 1803 | 1836 | 47.4962 | 50.0060 | 54.4128 | 0.3126 | 0.3292 | 50.01 |
8 | 2060 | 2081 | 2116 | 95.1074 | 100.1020 | 108.9733 | 0.3127 | 0.3291 | 100.10 |
9 | 2350 | 2372 | 2408 | 190.1609 | 200.2102 | 217.7541 | 0.3127 | 0.3292 | 200.21 |
10 | 2524 | 2546 | 2583 | 284.8473 | 299.6359 | 326.1913 | 0.3128 | 0.3290 | 299.64 |
Input Code Values | Output XYZ Tristimulus | Output Chromaticity Coordinates | Output Luminance | ||||||
---|---|---|---|---|---|---|---|---|---|
Step Number | Xβ³ | Yβ³ | Zβ³ | X | Y | Z | x | y | Y, cd/m 2 |
1 | 60 | 62 | 65 | 0.0047 | 0.0050 | 0.0055 | 0.3095 | 0.3296 | 0.0050 |
2 | 74 | 76 | 79 | 0.0071 | 0.0075 | 0.0081 | 0.3134 | 0.3302 | 0.0075 |
3 | 86 | 88 | 92 | 0.0096 | 0.0100 | 0.0109 | 0.3133 | 0.3281 | 0.0100 |
4 | 105 | 108 | 112 | 0.0143 | 0.0151 | 0.0163 | 0.3124 | 0.3309 | 0.0151 |
5 | 121 | 124 | 129 | 0.0191 | 0.0202 | 0.0219 | 0.3129 | 0.3293 | 0.0202 |
6 | 157 | 161 | 167 | 0.0333 | 0.0352 | 0.0381 | 0.3125 | 0.3300 | 0.0352 |
7 | 185 | 189 | 196 | 0.0478 | 0.0501 | 0.0544 | 0.3138 | 0.3291 | 0.0501 |
8 | 221 | 226 | 234 | 0.0714 | 0.0752 | 0.0815 | 0.3131 | 0.3296 | 0.0752 |
9 | 250 | 255 | 265 | 0.0952 | 0.0998 | 0.1093 | 0.3129 | 0.3279 | 0.0998 |
10 | 332 | 339 | 351 | 0.1895 | 0.1997 | 0.2180 | 0.3121 | 0.3289 | 0.1997 |
Input Code Values | Output XYZ Tristimulus | Output Chromaticity Coordinates | Output Luminance | ||||||
---|---|---|---|---|---|---|---|---|---|
Patch | Xβ³ | Yβ³ | Zβ³ | X | Y | Z | x | y | Y, cd/m 2 |
Red-1 | 2234 | 1925 | 68 |
| 68.1286 | 0.0060 | 0.6797 | 0.3202 | 68.13 |
Green-1 | 1988 | 2387 | 1327 | 79.6874 | 207.3498 | 13.5304 | 0.2651 | 0.6899 | 207.35 |
Blue-1 | 1871 | 1525 | 2565 | 59.4719 | 23.8562 | 313.0007 | 0.1501 | 0.0602 | 23.86 |
Cyan-1 | 2218 | 2434 | 2583 | 139.2100 | 231.3271 | 326.1913 | 0.1998 | 0.3320 | 231.33 |
Magenta-1 | 2383 | 2049 | 2565 | 205.4226 | 92.5848 | 313.0007 | 0.3362 | 0.1515 | 92.58 |
Yellow-1 | 2423 | 2510 | 1327 | 225.4889 | 275.8047 | 13.5304 | 0.4380 | 0.5357 | 275.80 |
Red-2 | 2169 | 1899 | 1058 | 123.8170 | 63.8256 | 5.7914 | 0.6401 | 0.3300 | 63.83 |
Green-2 | 2110 | 2402 | 1674 | 107.4021 | 214.7317 | 35.7149 | 0.3001 | 0.6001 | 214.73 |
Blue-2 | 1834 | 1491 | 2524 | 54.1359 | 21.7018 | 284.8473 | 0.1501 | 0.0602 | 21.70 |
Cyan-2 | 2280 | 2443 | 2576 | 161.2773 | 236.2112 | 320.9991 | 0.2245 | 0.3288 | 236.21 |
Magenta-2 | 2322 | 2016 | 2533 | 178.0633 | 85.3852 | 290.8102 | 0.3213 | 0.1541 | 85.39 |
Yellow-2 | 2432 | 2513 | 1731 | 230.2550 | 277.7188 | 41.4967 | 0.4190 | 0.5054 | 277.72 |
White-1 D65 | 2524 | 2546 | 2583 | 284.8473 | 299.6359 | 326.1913 | 0.3128 | 0.3290 | 299.64 |
White-2 D60 | 2509 | 2530 | 2534 | 275.1694 | 288.8093 | 291.4801 | 0.3217 | 0.3376 | 288.81 |
White-3 D55 | 2493 | 2513 | 2478 | 265.1950 | 277.7188 | 256.1598 | 0.3319 | 0.3476 | 277.72 |
The following parameters are also important to picture quality, but because they are difficult to measure with todayβs readily available instrumentation, they are generally assessed subjectively.
Instrumentation designers are encouraged to design and manufacture equipment that can be used to translate subjective parameters into objective performance characterization.
Using
the
black-to-white
gray
step-scale
test
pattern,
the
entire
step-scale
appears
neutral
without
any
visible
color
non-uniformity.
The
black-to-white
gray
step-scale
test
pattern
is
centered
on
the
display
and
occupies
a
rectangle
sized
20%
of
the
screen
height
by
80%
of
the
screen
width.
The
background
is
defined
by
code
values
[1000
1015
1040],
which
define
a
luminance
of
5.0
cd/m2
cd/m
2
and
chromaticity
coordinates
x
=
0.3124
y
=
0.3291.
Each
step
is
8%
of
the
screen
width
and
is
defined
by
the
code
values
in
Table
3
4
.
Using
the
black-to-dark
gray
step-scale
test
pattern,
the
entire
step-scale
appears
neutral
without
any
visible
color
non-uniformity.
The
black-to-dark
gray
step-scale
test
pattern
is
centered
on
the
display
and
occupies
a
rectangle
sized
20%
of
the
screen
height
by
80%
of
the
screen
width.
The
background
is
defined
by
code
values
[122
124
129],
which
define
a
luminance
of
0.020
cd/m
2
and
chromaticity
coordinates
x
=
0.3129
y
=
0.3293.
Each
step
is
8%
of
the
screen
width
and
is
defined
by
the
code
values
in
Table
4
5
.
All measurements shall be made in the center of the Screen while in a lab environment such that no contamination from ambient light contributes to the output luminance.
Contouring is the appearance of steps or bands where only a continuous or smooth gradient is expected. Because contouring is a function of many variables, it is important to look at a series of test patterns with shallow gradations to simulate naturally occurring gradations in images.
Examples include horizons, particularly at sunset or sunrise, and the natural falloff around high intensity spotlights, particularly if diffused by atmosphere or lens filtration. These test pattern ramps have a step width of no less than 4 pixels with an increment of one code value per step and are placed on a background equal to the minimum value in the ramp, so that the eye is adapted for maximum sensitivity.
Since dynamic fades to black are widely used in real-world content, a dynamic test pattern that fades slowly to black is another useful approach.
Each image is viewed in the proper environment as defined in Section 7 , and ought not to exhibit any contouring (step in luminance), or color deviation from the neutral gray.
The color image encoding parameters for todayβs HDR Reference Displays and the corresponding color conversion steps to convert from P3D65 Rβ²Gβ²Bβ² to Xβ³Yβ³Zβ³ and from Xβ³Yβ³Zβ³ to P3D65 RGB are shown here as an example for implementation. P3D65 is defined in [SMPTE ST 2113] .
Encoding Primaries |
---|
R (x, y) = (0.6800, 0.3200) |
G (x, y) = (0.2650, 0.6900) |
B (x, y) = (0.1500, 0.0600) |
White Reference |
---|
(x, y) = (0.3127,0.3290) |
The Reference White Luminance is 299.6 cd/m 2 .
Color conversion from Rβ²Gβ²Bβ² to Xβ³Yβ³Zβ³ typically involves the following five-step process:
The transfer function of the HDR Reference Display is explicitly specified by [SMPTE ST 2084] . The actual coefficients of the color transform matrices depend on the color primaries of the Mastering HDR Reference Display (encoding side) and the Cinema HDR Display (decoding side), and their respective white points.
[SMPTE ST 2084] is a defined standard, and 12-bit quantization is sufficient, so a normalized PQ is not needed. Using a normalized PQ might impede the cross-utilization of assets in other formats.
The processing steps for converting 12 bit Rβ²Gβ²Bβ² code values (which range from 0 to 4095) of the color-graded master to device-independent Xβ³Yβ³Zβ³ are shown below.
This color space conversion can be implemented within the color corrector or applied in a separate batch process. The equations below combine step #1 (inverse quantization) and step #2 ( [SMPTE ST 2084] EOTF):
where:
The output (RGB) of this linearization is a floating point number that ranges from 0.0 to 10000.0. The 3x3 linear matrix is then applied to this signal, resulting in a linear XYZ signal with floating point values that range from 0.0 to 10000.0. To minimize quantization errors, this matrix should be implemented as a floating point calculation. The matrix is shown here to 14 significant digits.
Finally, the Xβ³Yβ³Zβ³ encoding transfer function is defined by the following expression which performs both step #4 (Inverse-EOTF) and step #5 (12bit Quantization). This equation does not compensate for the screen black level, so it represents an absolute encoding of the light levels independent of the screen black level.
where:
The
unary
function
The Xβ³Yβ³Zβ³-to-P3D65 RGB processing steps for a Cinema HDR Display with the same color primaries as the HDR Reference Display are shown below and defined by the following steps:
The equations below show step #1 (inverse quantization) and step #2 ( [SMPTE ST 2084] EOTF) combined:
where:
Apply XYZ to P3D65 color encoding primaries transformation:
The resulting linear RGB light levels may end up being converted to other formats as the image data flows through the image/display processing operations involved in ultimately displaying the image to the viewer via the HDR display.
If other formats within the HDR display that may have a limited precision, it is important to preserve the visual fidelity/accuracy that is achievable with the 12 bit Xβ³Yβ³Zβ³ [SMPTE ST 2084] distribution format across the minimum gamut (luminance range and color volume) specified elsewhere in this document to ensure that additional fidelity isnβt loss.