Wide Color Gamut SET EXPO 2016
31 AUGUST 2016
Eliésio Silva Júnior Reseller Account Manager E/ [email protected] T/ +55 11 3530-8940 M/ +55 21 9 7242-4211 tek.com Anatomy Human Vision
CIE Chart
Color Gamuts
Wide Color Gamut
Gamma and High Dynamic Range
2 Basic Anatomy - Human vision system PHYSICAL PART/ELEMENTS • 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
http://webvision.med.utah.edu/index.html
3 Color Model – CIE color spaces
NTSC (1953) BT709/sRGB BT2020 ~SMPTE C D65 white BT2020 NTSC (1953)
Black BT709/sRGB (70% NTSC) White ~SMPTE C D65 white
CIE-1931 chart CIE-1976 chart (More perceptually uniform than CIE-1931) • 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
4 ITU 601-7 & 709-5 Chromaticity
ITU-R BT 601-7
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
ITU-R BT 709-5
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
31 AUGUST 2016 5 Wider Color - Chromaticity
ITU-R BT 2020 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 709-5
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
31 AUGUST 2016 6 Wider Color - Chromaticity
SMPTE 2048-1 Free Scale (FS) Gamut CIE x CIE y
Red 0.73470 0.26530
Green 0.14000 0.86000
Blue 0.10000 -0.02985
White 0.31272 0.32903
X’Y’Z’ Color Space EG431-2 (P3) 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
31 AUGUST 2016 7 ACES Color Space - Academy Color
Encoding System CIE x CIE y
Red 0.73470 0.26530
Green 0.00000 1.00000
Blue 0.00010 -0.07700
Color image encoding system created by the Academy of Motion Picture Arts and Sciences that allows for a fully encompassing color accurate workflow.
31 AUGUST 2016 8 Wide(er) Color Gamut Percentage
BT2020 NTSC (1953)
BT709/sRGB (70% NTSC) ~SMPTE C D65 white . NTSC occupies 47.3% of CIE Chart 1931
. 709 occupies 33.5% of CIE chart 1931
CIE-1931 chart . 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
Transport QAM Stream Optical Baseband • File- DVB SET TOP MPEG DISPLAY Video Signal Based ISDB-TB BOX Video FTP
11 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
100% Color Bars SD 525 RGB
SD 525 YPbPr HD 1080 YPbPr
13 HD/UHD (709) YPbPr and UHD (2020)
HD 1080 YPbPr UHD (709) YPbPr
UHD (2020) YPbPr / 525 UHD (709) & (2020) YPbPr
14 4K Monitoring – ITU-R BT.2020
15 Gamut
1616 Gamut
1717 Gamut
1818 Gamut
1919 Gamut
20 Gamut
21 Gamut
2222 Color Space
2323 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?
31 AUGUST 2016 24 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 nits Looking at the sun > 1 billion nits (don’t look at it)
Shadows: .1 to 10 nits Lap top or TV: 100 to 200 nits With day adapted eye shadows (hard to see in bright daylight can be 10 nits. In living room, less than 0.1 nits
25 Total Visual Dynamic Range
HDR MAPPING INTO CAMERA F-STOPS (0 STOP = 18% REFLECTANCE)
10^8 (5000 nits)8
6
Sunlight 10^6 Pull
Sun light Bright adaption outdoor 24 4
outdoor Photopic -
10^4 someadaption stopswith
ST.2084DisplayHDR (100nits)2.5 Sony, Sony, ARRI, Canon
Bright adaption Bright (90%) 2
Adapted Eye Adapted Adapted Eye Indoor 7
10^2 -
~16 stops indoor ~7
lighting
- stops Lighting - (18%) 20 stops (20nits) 0 (18%)
10^0 Mesopic -2 Moonlight moonlight Adaption Dark 10^-2
-4
Scotopic adaption
starlight Push Dark Dark 10^-4 Starlight -6
10^-6 (.08 nits) -8 Nits (cd/m^2) Stops
26 Potential Issues with Bright HDR displays
• 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.
27 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)
31 AUGUST 2016 28 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).
31 AUGUST 2016 29 Capturing a Camera RAW image
0% Black 18% Grey 90% Reflectance Gamma 10-bit Code-Value % (20 nits illumination) % % 10-bit Code-Value 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
31 AUGUST 2016 30 Camera (scene) referenced 709 to PQ LUT conversion
Camera-Side Conversion Camera-sideBT.709 to conversion PQ BT.709 to PQ 100 2084 HDR 0% 2% 18 % 90% 100% 90 9 41 709 0 9 41 95 100 80 100nits SDR BT.709,100,1000
70 SDR BT.709,100,2000 SDR_2_HDR_CSBT709,100,1000 HDR 1000nits 0 37 58 75 76 i 60 SDR BT.709,100,5000 SDR_2_HDR_CSBT709,100,2000 i 50 HDR 2000nits 0 31 51 68 68 SDR_2_HDR_CSBT709,100,5000 i 40
HDR 5000nits 0 24 42 58 59 30
20
10
0 0 20 40 60 80 100 BT709 BT.709 %i IRE SDR and HDR displays DO NOT match. % or IRE Blacks are stretched in the BT1886 Display but not the PQ Display (matches scene)
31 AUGUST 2016 31 Studio Monitor referenced 709 to PQ LUT conversion
Display-Side Conversion Display-side convBT.709 ersio n BT.7 09 to PQto PQ 1 0 0 2084 HDR 0% 2% 18 % 90% 100% 90 9 41 709 0 9 41 90 100 80 100nits HDR BT.709,100,1000
70 HDR BT.709,100,2000 SDR_ 2_HDR_DS BT 7 0 9 , 1 0 0 , 1 0 0 0 HDR 1000nits 0 22 52 74 75 i 60 HDR BT.709,100,5000 SDR_ 2_HDR_DS BT 7 0 9 , 1 0 0 , 2 0 0 0 i 50 HDR 2000nits 0 17 46 66 68 SDR_ 2_HDR_DS BT 7 0 9 , 1 0 0 , 5 0 0 0 i 40
HDR 5000nits 0 13 37 57 58 30
20
10
0 0 20 40 60 80 1 0 0 BT 7 0 9 BT.709 %i IRE SDR and HDR displays match % o r IRE Blacks are stretched in both the BT1886 and PQ Display
31 AUGUST 2016 32 SMPTE 2084 PQ Look Up Tables
Linear Ramp Test Signal Look Up Table Look Up Table BT.709 SMPTE 2084 1000nits SMPTE 2084 1000nits Reference White 100nits Reference White 300nits
31 AUGUST 2016 33 Slog 2 Camera RAW to HDR
HDR 1000 Nits Look Up Table Converted SLog2 to ST 2084 PQ 90% Reflectance White 75%, 18% Grey 58% Need HDR Monitor to view this image.
31 AUGUST 2016 34 Slog 2 Camera RAW to HDR
HDR 1000 Nits 90% Reflectance White 75%, 18% Grey 58%
31 AUGUST 2016 35 Gamma
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
31 AUGUST 2016 36 Colour Model
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)
31 AUGUST 2016 37 Gamut
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.
31 AUGUST 2016 38 Colour Space
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
31 AUGUST 2016 39 Summary GAMMA AND HIGH DYNAMIC RANGE • 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
31 AUGUST 2016 40 Thank you very much
See you at booth 33
Eliésio Silva Júnior Reseller Account Manager E/ [email protected] M/ + 55 21 9 7242-4211