Wide Color Gamut SET EXPO 2016

Transcription

1 Wide Color Gamut SET EXPO AUGUST 2016 Eliésio Silva Júnior Reseller Account Manager E/ T/ M/ tek.com

2 Anatomy Human Vision CIE Chart Color Gamuts Wide Color Gamut Gamma and High Dynamic Range 2

3 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 3

4 Color Model CIE color spaces BT2020 NTSC (1953) BT2020 NTSC (1953) BT709/sRGB ~SMPTE C D65 white Black White BT709/sRGB (70% NTSC) ~SMPTE C D65 white CIE 1931 XYZ color space Still foundation of most color models CIE-1931 chart CIE-1976 chart (More perceptually uniform than CIE-1931) Trichromatic stimulus (color value) Lightness decreases towards not shown third dimmension Saturation increases towards edges 4

5 ITU & Chromaticity ITU-R BT CIE x CIE y Red Green Blue White ITU-R BT / CIE x CIE y Red Green Blue White AUGUST

6 Wider Color - Chromaticity ITU-R BT 2020 CIE x CIE y Red Green Blue White ITU-R BT CIE x CIE y Red Green Blue White AUGUST

7 Wider Color - Chromaticity SMPTE Free Scale (FS) Gamut CIE x CIE y Red Green Blue White X Y Z Color Space EG431-2 (P3) CIE x CIE y Red Green Blue DCI P3 D AUGUST

8 ACES Color Space - Academy Color Encoding System CIE x CIE y Red Green Blue 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

9 Wide(er) Color Gamut Percentage BT2020 NTSC (1953) BT709/sRGB (70% NTSC) ~SMPTE C D65 white NTSC occupies 47.3% of CIE Chart occupies 33.5% of CIE chart 1931 CIE-1931 chart DCI-P3 occupies 44.5% of CIE Chart occupies 63.3% of CIE Chart

10 Wide(er) Color Gamut 10

11 Wide(er) Color Gamut Video Ecosystem Baseband Video MPEG Signal Transport Stream File- Based Video QAM Optical DVB ISDB-TB FTP SET TOP BOX DISPLAY 11

12 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

13 525 RGB to SD (601) & HD (709) YPbPr 100% Color Bars SD 525 RGB SD 525 YPbPr HD 1080 YPbPr 13

14 HD/UHD (709) YPbPr and UHD (2020) HD 1080 YPbPr UHD (709) YPbPr UHD (2020) YPbPr / 525 UHD (709) & (2020) YPbPr 14

15 4K Monitoring ITU-R BT

16 Gamut 16 16

17 Gamut 17 17

18 Gamut 18

19 Gamut 19

20 Gamut 20

21 Gamut 21

22 Gamut 22

23 Color Space 23

24 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

25 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) Lap top or TV: 100 to 200 nits (hard to see in bright daylight Shadows:.1 to 10 nits With day adapted eye shadows can be 10 nits. In living room, less than 0.1 nits 25

26 Bright adaption Pull Bright adaption Total Visual Dynamic Range HDR MAPPING INTO CAMERA F-STOPS (0 STOP = 18% REFLECTANCE) 10^8 (5000 nits)8 Indoor Lighting Starlight Sunlight outdoor Moonlight 10^6 10^4 10^2 (18%) 20 10^0 10^-2 10^-4 Sun light outdoor indoor lighting moonlight starlight Photopic Mesopic Scotopic 24-stops with some adaption ST.2084 HDR Display Adapted Eye Dark Adaption 7-stops Sony, ARRI, Canon ~16-stops Push 6 4 (100nits)2.5 (90%) 2 (20nits) 0 (18%) Adapted Eye ~7-stops Dark adaption 10^-6 Nits (cd/m^2) (.08 nits) -8 Stops 26

27 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

28 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

29 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

30 Capturing a Camera RAW image Gamma 0% Black 10-bit Code-Value % 18% Grey (20 nits illumination) 10-bit Code-Value % 90% Reflectance 10-bit Code-Value % S Log S Log S Log LogC C-Log ACES (proxy) ND ND BT AUGUST

31 Camera (scene) referenced 709 to PQ LUT conversion 2084 HDR 0% 2% 18 % 90% 100% nits Camera-Side Conversion BT.709 to PQ Camera-side conversion BT.709 to PQ 9 41 SDR BT.709,100, SDR_2_HDR_CS, BT709, i SDR_2_HDR_CS, BT709, i HDR 1000nits HDR 2000nits SDR_2_HDR_CS, BT709, i SDR BT.709,100,2000 SDR BT.709,100,5000 HDR 5000nits BT.709 % IRE SDR and HDR displays DO NOT match. Blacks are stretched in the BT1886 Display but not the PQ Display (matches scene) BT709 i % or IRE 31 AUGUST

32 Studio Monitor referenced 709 to PQ LUT conversion 2084 HDR 0% 2% 18 % 90% 100% Display-Side Conversion BT.709 to PQ Display-side conv ersio n BT.7 09 to PQ nits HDR BT.709,100,1000 HDR 1000nits S D R_ 2 _ H DR _ DS BT 7 0 9, 1 0 0, i S D R_ 2 _ H DR _ DS BT 7 0 9, 1 0 0, i HDR 2000nits S D R_ 2 _ H DR _ DS BT 7 0 9, 1 0 0, i HDR BT.709,100,2000 HDR BT.709,100,5000 HDR 5000nits SDR and HDR displays match Blacks are stretched in both the BT1886 and PQ Display BT.709 % IRE BT i % o r IRE 31 AUGUST

33 SMPTE 2084 PQ Look Up Tables Linear Ramp Test Signal BT.709 Look Up Table SMPTE nits Reference White 100nits Look Up Table SMPTE nits Reference White 300nits 31 AUGUST

34 Slog 2 Camera RAW to HDR HDR 1000 Nits 90% Reflectance White 75%, 18% Grey 58% Look Up Table Converted SLog2 to ST 2084 PQ Need HDR Monitor to view this image. 31 AUGUST

35 Slog 2 Camera RAW to HDR HDR 1000 Nits 90% Reflectance White 75%, 18% Grey 58% 31 AUGUST

36 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

37 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

38 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

39 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

40 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

41 Thank you very much See you at booth 33 Eliésio Silva Júnior Reseller Account Manager E/ M/