Need for HDR
Consumer WCG, HDR films, series, news, sports (BT.2100 PQ, HLG)
Consumer WCG, HDR-ready TVs commonplace
Consumer WCG (P3) laptops, tablets, phones; HDR coming
WCG, HDR still images coming (AVIF)
CIE Lab
By Chris Lilley, W3C
Consumer WCG, HDR films, series, news, sports (BT.2100 PQ, HLG)
Consumer WCG, HDR-ready TVs commonplace
Consumer WCG (P3) laptops, tablets, phones; HDR coming
WCG, HDR still images coming (AVIF)
General forum for expert discussion, whether W3C Member or not
Draft report is a gap analysis, collection of issues
TAG review of Lab concluded:
W3C is an associate member of ICC
Working Groups on Displays, Profile Evaluation
Security review of ICC profiles & associated software
New Working Group on HDR (June 2020)
Paper on HDR and ICC Profile Connection Space
Fully color space aware, wide support of color models
Covers CSS Color 4, CSS Color 5, CSS Color HDR
Gamut mapping, color interpolation, deltaE
Informs Houdini CSS Typed Object Model
Fairchild HDR-Lab extends Lightness to 400
Exaggeration of large Chroma remains
Blue hue non-linearity (curve to purple)
Increasingly complex metrics: ΔE76, ΔECMC(2:1) and ΔE2000
Brighter displays for brighter environments
Brighter displays for more highlights
Correction term for blue non-linearity
Starts with absolute D65 XYZ, 0 to 10,000 cd/m²
Transform to sharpened LMS domain
BT.2100 PQ transfer function
ΔEJz = √(ΔJz² + ΔCz² + ΔHz²)
ΔHz = 2 × √(Cz1 × Cz2) × sin(Δh), Δh in radians
| Reference | Sample | ΔE76 | ΔECMC(2:1) | ΔE2000 | ΔEJz | ΔEJz × 400 |
|---|---|---|---|---|---|---|
| white | black | 100 | 33.7401 | 100 | 0.193556 | 77.4225 |
| white | white | 0 | 0 | 0 | 0 | 0 |
| lab(50 2.5 0) | lab(73 25 -18) | 36.8680 | 37.9233 | 27.1492 | 0.070663 | 28.2651 |
| lab(50 2.5 0) | lab(61 -5 29) | 31.9100 | 34.4758 | 22.8977 | 0.054039 | 21.6158 |
| lab(50 2.5 0) | lab(56 -27 -3) | 30.2531 | 38.0618 | 31.9030 | 0.054381 | 21.7524 |
| lab(50 2.5 0) | lab(58 24 15) | 27.4089 | 33.3342 | 19.4535 | 0.048484 | 19.3936 |
| lab(84.25 5.74 96.00) | lab(84.46 8.88 96.49) | 3.1849 | 1.6364 | 1.6743 | 0.007603 | 3.0412 |
| lab(84.25 5.74 96.00) | lab(84.52 5.75 93.09) | 2.9225 | 0.8770 | 0.5887 | 0.002040 | 0.8160 |
| lab(84.25 5.74 96.00) | lab(84.37 5.86 99.42) | 3.4242 | 1.0221 | 0.6395 | 0.002199 | 0.8796 |
HDR aspect of Jzazbz little explored
A UCS with HLG might apply to more viewing conditions, without re-rendering
Hue linearity of Jzazbz needs to be further investigated
ICTCP also needs evaluation.