Wide Color GamutSET EXPO 2016
31 AUGUST 2016
Eliésio Silva JúniorReseller Account Manager E/ [email protected]/ +55 11 3530-8940 M/ +55 21 9 7242-4211 tek.com
Anatomy Human Vision
CIE Chart
Color Gamuts
Wide Color Gamut
2
Gamma and High Dynamic Range
http://webvision.med.utah.edu/index.html
• Eye, Lens and Retina
▪ Rods
▫ Sensitive to Blue-green light
▫ Used for vision under dark-dim conditions.
▪ Cones
▫ 3 Types of Cones
Sensitive to either
long wavelengths of light (red light)
medium wavelengths of light (green light)
short wavelengths of light (blue light)
◦ Optic nerve
Basic Anatomy - Human vision systemPHYSICAL PART/ELEMENTS
3
Color Model – CIE color spaces
4
BT709/sRGB(70% NTSC)~SMPTE C
BT2020
CIE-1931 chart
D65 white
NTSC(1953)
• CIE 1931 XYZ color space
◦ Still foundation of most color models
• Trichromatic stimulus (color value)
• Lightness decreases towards not shown third dimmension
• Saturation increases towards edges
CIE-1976 chart(More perceptually uniform than CIE-1931)
D65 white
BT2020
BT709/sRGB~SMPTE C
NTSC(1953)
Black
White
ITU 601-7 & 709-5 Chromaticity
601-7 525 CIE x CIE y
Red 0.630 0.340
Green 0.310 0.595
Blue 0.155 0.070
White 0.3127 0.3290
5
709-5/601 625 CIE x CIE y
Red 0.640 0.330
Green 0.300 0.600
Blue 0.150 0.060
White 0.3127 0.3290
ITU-R BT 709-5
ITU-R BT 601-7
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Wider Color - Chromaticity
6
CIE x CIE y
Red 0.708 0.292
Green 0.170 0.797
Blue 0.131 0.046
White 0.31272 0.32903
ITU-R BT 2020
709-5 CIE x CIE y
Red 0.640 0.330
Green 0.300 0.600
Blue 0.150 0.060
White 0.3127 0.3290
ITU-R BT 709-5
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Wider Color - Chromaticity
7
CIE x CIE y
Red 0.73470 0.26530
Green 0.14000 0.86000
Blue 0.10000 -0.02985
White 0.31272 0.32903
CIE x CIE y
Red 0.680 0.3230
Green 0.2650 0.6900
Blue 0.150 0.06000
DCI P3 D65 0.3127 0.3290
SMPTE 2048-1 Free Scale (FS) Gamut
X’Y’Z’ Color Space EG431-2 (P3)
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ACES Color Space - Academy Color Encoding System
8
CIE x CIE y
Red 0.73470 0.26530
Green 0.00000 1.00000
Blue 0.00010 -0.07700
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Color image encoding system created
by the Academy of Motion Picture Arts
and Sciences that allows for a fully
encompassing color accurate workflow.
Wide(er) Color Gamut Percentage
BT709/sRGB(70% NTSC)~SMPTE C
BT2020
CIE-1931 chart
D65 white
NTSC(1953)
NTSC occupies 47.3% of CIE Chart 1931
709 occupies 33.5% of CIE chart 1931
DCI-P3 occupies 44.5% of CIE Chart 1931
2020 occupies 63.3% of CIE Chart 1931
9
Wide(er) Color Gamut
10
Wide(er) Color Gamut Video Ecosystem
11
BasebandVideo
MPEGSignal
TransportStream
• File-BasedVideo
QAM
Optical
DVB
ISDB-TB
FTP
SET TOP BOX
DISPLAY
RGB and YPbPr Color Space
• YPbPr color cube shows Parallel-Piped of RGB colors
• Certain YPbPr values when converted to RGB will fall outside the
allowed range and will be out of Gamut
12
525 RGB to SD (601) & HD (709) YPbPr
13
100% Color Bars SD 525 RGB
SD 525 YPbPr HD 1080 YPbPr
HD/UHD (709) YPbPr and UHD (2020)
14
UHD (709) YPbPr
UHD (2020) YPbPr / 525
HD 1080 YPbPr
UHD (709) & (2020) YPbPr
15
4K Monitoring – ITU-R BT.2020
16
Gamut
16
17
Gamut
17
18
Gamut
18
19
Gamut
19
20
Gamut
20
21
Gamut
21
22
Gamut
22
23
Color Space
23
Why does HDR look better than SDR ?
• Are HDR screens brighter on average?
• Are HDR screens darker on average with blacker blacks?
• Is the average picture level (APL) unchanged?
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Why does HDR look better than SDR
HDR RETAINS BRIGHT SPECULAR HIGHLIGHTS AS WELL AS
DETAIL IN BLACKS
WHICH CAN MAKE COLORS APPEAR MORE SATURATED.
Sky Light: >500K nitsLooking at the sun > 1 billion nits(don’t look at it)
Lap top or TV: 100 to 200 nits(hard to see in bright daylight
Shadows: .1 to 10 nitsWith day adapted eye shadowscan be 10 nits. In living room, less than 0.1 nits
25
Total Visual Dynamic Range
26
HDR MAPPING INTO CAMERA F-STOPS (0 STOP = 18% REFLECTANCE)
Nits (cd/m^2)
Meso
pic
Ph
oto
pic
Scoto
pic
ST.20
84
HD
R D
isplay
Son
y, AR
RI, C
ano
n~1
6-sto
ps
Pu
sh
Pu
ll
10^8
10^-6
10^6
10^4
10^2
10^0
10^-2
10^-4
(18%) 20
starlight
moonlight
indoorlighting
Sun lightoutdoor 2
4-sto
ps w
ith so
me
adap
tion
Ad
apte
d Eye
Bri
ght
adap
tio
n
Dark A
dap
tion
7-sto
ps
Sunlightoutdoor
IndoorLighting
Moonlight
Starlight
(5000 nits)8
(.08 nits) -8
6
4
2
-2
-4
(20nits) 0
-6
Stops
Ad
apte
d Eye
~7-sto
ps
Bri
ght
adap
tio
n
Dark
adap
tion
(100nits)2.5
(18%)
(90%)
Potential Issues with Bright HDR displays
27
• Color shift in the Mesopic-level adaption (dark viewing environment)• As light moves below Photopic (dominated by cones) and gets closer to Scotopic (dominated by rods) color
saturation will diminish.• This may occur in dark scenes in low-light home theater.
• Light/Dark Adaption (bleaching process rather than pupil size)• Sustained bright images cause the photo-pigment in the retina to reduce and can result in the perception
of after images. • Dark adaption can take seconds or even minutes. Changes to dark scenes from bright scenes may take
more time in dark theater as opposed to same scene in higher ambient light.
• Viewing distance• Static adaption is only about 7 to 9 stops.• To take full advantage of HDR (> 9 stops) via local adaption, you have to be closer than 2 screen widths• If you do sit this close, you may get eye strain
• Large Area Flicker • Strobing of high peak light levels may cause distress to some viewers. Perceptual flicker frequency may be
increased since it is a function of retinal adaption. May contribute to PSE (BT.1702). • Frame rate judder may be more visible.
Proposed HDR Formats
• SMPTE ST.2084:2014 High Dynamic Range Electro-Optical Transfer Function of Mastering
Reference Displays
“Dolby Vision”
Perceptual Quantizer (PQ) based on Barten contour perception
EOTF is inverse of OETF allowing .001 to 10K nits with 10-bits
Current “Pulsar” display peaks at about 4K nits
• Hybrid Log-Gamma, “HLG”, from BBC/NHK (ARIB STD-B67)
Extends log processing (de-facto in many cameras) of high brightness peaks to mitigate blown-out or clipped whites
Seamless “gamma” power-law processing in blacks as in BT.709/BT.2020 but without linear segment
Displays can evolve to allow 400X to 800X increase in display
Allows display EOTF to adjust system gamma to correct for surround illumination (i.e. 10 nits to 500 nits)
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Proposed HDR Formats
• Philips Parameter-based from HDR master
Embed low bit-rate HDR and SDR conversion parameters into metadata
Extract parameters during decode and tune display for peak luma
Optional Y’u’v’ encoding (more perceptually uniform)
• Technicolor Video Mastering and Distribution Workflow
Grade both an HDR and SDR master
Vital to maintain “Artistic Intent”
• Academy Color Encoding System (ACES)
(dynamic range and wide color gamut preserving workflow, not an HDR format)
33 bit floating point
10-bit proxy output in stops (log2).
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Capturing a Camera RAW image
Gamma0% Black
10-bit Code-Value %18% Grey
(20 nits illumination)10-bit Code-Value
%90% Reflectance
10-bit Code-Value%
S Log 1 90 3 394 37.7 636 65
S Log 2 90 3 347 32.3 582 59
S Log 3 95 3.5 420 40.6 598 61
LogC 134 3.5 400 38.4 569 58
C-Log 128 7.3 351 32.8 614 63
ACES (proxy) ND ND 426 41.3 524 55
BT.709 64 0 423 41.0 940 100
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Camera (scene) referenced 709 to PQ LUT conversion
31
0 20 40 60 80 1000
10
20
30
40
50
60
70
80
90
100
Camera-side conversion BT.709 to PQ
% or IRE
SDR_2_HDR_CS,,BT709i1001000
SDR_2_HDR_CS,,BT709i1002000
SDR_2_HDR_CS,,BT709i1005000
9 41
BT709i
Camera-Side ConversionBT.709 to PQ
BT.709 % IRE
SDR BT.709,100,1000
SDR and HDR displays DO NOT match.Blacks are stretched in the BT1886 Display but not the PQ Display (matches scene)
SDR BT.709,100,2000
SDR BT.709,100,5000
2084 HDR 0% 2% 18 % 90% 100%
709 100nits
0 9 41 95 100
HDR 1000nits 0 37 58 75 76
HDR 2000nits 0 31 51 68 68
HDR 5000nits 0 24 42 58 59
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Studio Monitor referenced 709 to PQ LUT conversion
32
0 2 0 4 0 6 0 8 0 1 0 00
1 0
2 0
3 0
4 0
5 0
6 0
7 0
8 0
9 0
1 0 0
Display-side conv ersio n BT.7 09 to PQ
% o r IRE
S D R_ 2 _ H DR _ DS ,,BT 7 0 9i
1 0 0 1 0 0 0
S D R_ 2 _ H DR _ DS ,,BT 7 0 9i
1 0 0 2 0 0 0
S D R_ 2 _ H DR _ DS ,,BT 7 0 9i
1 0 0 5 0 0 0
9 4 1
BT 7 0 9i
SDR and HDR displays matchBlacks are stretched in both the BT1886 and PQ Display
Display-Side ConversionBT.709 to PQ
BT.709 % IRE
HDR BT.709,100,1000
HDR BT.709,100,2000
HDR BT.709,100,5000
2084 HDR 0% 2% 18 % 90% 100%
709 100nits
0 9 41 90 100
HDR 1000nits 0 22 52 74 75
HDR 2000nits 0 17 46 66 68
HDR 5000nits 0 13 37 57 58
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SMPTE 2084 PQ Look Up Tables
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Linear Ramp Test SignalBT.709
Look Up TableSMPTE 2084 1000nits
Reference White 100nits
Look Up TableSMPTE 2084 1000nits
Reference White 300nits
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Slog 2 Camera RAW to HDR
34
HDR 1000 Nits90% Reflectance White 75%, 18% Grey 58%
Look Up Table Converted SLog2 to ST 2084 PQ
Need HDR Monitor to view this image.
31 AUGUST 2016
Slog 2 Camera RAW to HDR
35
HDR 1000 Nits90% Reflectance White 75%, 18% Grey 58%
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Gamma
36
Gamma correction, gamma nonlinearity, gamma encoding, or
simply gamma, is the name of a nonlinear operation used to code
and decode luminance in video or still image systems
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Colour Model
37
A colour model is an abstract mathematical model describing the
way color can be represented as tuples of numbers, typically as
three or four value or color components ( e.g RGB are CMYK are
color models)
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Gamut
38
In color reproduction, including computer graphics and
photography, the gamut, or color gamut, is a certain complete
subset of colors.
The most common usage refers to the subset of colors which can
be accurately represented in a given circumstance, such as within
a given color space or by a certain output device.
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Colour Space
39
Color space is a more specific term for a certain combination of a
color model plus a mapping function, the term “color space” tends
to be used to also identify color models, since identify a color
space automatically identifies the associated color model.
Gamut + Colour Model = Colour Space
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Summary
• Camera’s today are able to capture a wide dynamic range
• SDR displays typically clip or blow out the highlights of the image
• The use of non-linear processing such as S-Log 2, ST 2084 PQ
and HLG use the bits more efficiently to capture the image
• Overall this allows HDR displays to utilize the bits more effectively
• White point and 18% grey levels need to be set correctly using a
waveform monitor to simplify the process
40
GAMMA AND HIGH DYNAMIC RANGE
31 AUGUST 2016
Thank you very much
See you at booth 33
Eliésio Silva Júnior
Reseller Account Manager
M/ + 55 21 9 7242-4211