high dynamic range (hdr) · 2021. 5. 17. · nbcu, in collaboration with cromorama, and building on...

High Dynamic Range (HDR)

Our Evolution

- Where we started

- Decisions we made driven by our philosophy

- What it took to get to where we are

- What’s next?

NBCU LUTs and Single Stream Recommendation

NBCU, in collaboration with Cromorama, and building on ITU working group discussions for HDR operational practices involving Dolby, BBC and Philips, has developed techniques to enable “single-stream” production that feeds both UHD HDR and SDR transmission simultaneously.

The NBCU LUTs developed for this workflow enable single-stream production whereby the HDR and SDR products are consistent to the point where the benefits of HDR are realized making a unified production possible. Subsequently we’re sharing these efforts with the broadcast community for continued collaboration and use in production and distribution.

The NBCU LUTS include both HLG and PQ LUTs following similar HDR/SDR conversion methodology and color science.

NBCU has a commitment to industry collaboration and would like to encourage consistent media exchange, therefore we are willing to provide the NBCU LUTs freely. The NBCU LUTs are provided on an “as is” basis with no warranties.The package of NBCU LUTs with additional documentation are available at the following link:

NBCU LUT Single-Stream Recommendations and LUT Package

Chris Seeger and Michael Drazin are happy to answer questions pertaining to this effort and provide further insight into workflow.

Chris SeegerChris.Seeger@nbcuni.com

Michael Drazinmichael.drazin@nbcuni.com

We ask that manufactures include an acknowledgment in their license to their customers that the LUTs were “developed by NBCUniversal Media, LLC.”

Overview

Our Productionsbaseband

Our ProductionsFile based

Shading

NBCU LUTs

The focus of the entire conversion effort is to maintain the original artistic intent such that the SDR derived from the NBCU LUT compared side-by-side is consistent with the HDR until the point where the advantages of HDR are realized even with a reduction of dynamic range in the converted SDR.

NBCU HLG to PQ LUTs

The NBCU LUT7 converts HLG to PQ LUT using a mathematically transparent equation which normalizes HLG at 1,000 NITS and preserving the original artistic intent from the production to transmission.

Preserving Color Intent

HDR TO SDR - Original Saturation not preserved

HDR TO SDR – Color Clipping

NBCU LUT

Color Light

Objective LUT Testing

Perceptual Objective Color Volume Metrics

I

T

P

ITP Mimics perceptual aspects of the human visual system

“L”, “M”, “S” captures different wavelengths of light which represent specific color ranges

“I” Captures Intensity (or amount of light)

Objective LUT Testing

PERCEPTUAL OBJECTIVE METRICS

ABSOLUTE OBJECTIVE METRICS

Normalized Plotting Space

Normalized Plotting Space

Preserving Color IntentSDR to HLG Scene vs Display Light Conversion

Objective LUT Testing

T/P components from I-T-P allow us to visualize subtle hue shifts

Sarnoff Yellow Brick Road Pattern

This Plot Compares Sources vs Conversions• Source 1 = HLG BT.2020 (BT.2020 colors) (BLUE)• Source 2 = SDR BT.709 (BT.709 colors) (GREEN)• Source 3 = HLG to SDR LUT3 (RED)

Test PatternsBT2111

Questions?

Thank You.

ANNEX

ITU BT.2408 Recommendations for SDR <-> HDRScene vs Display Light Conversion

SDR converted to HDRw/NBCU LUT

SDR Original HLG

SDR converted to HDRw/NBCU LUT

SDR Original HLG

HDR converted to SDRw/NBCU LUT

HDR converted to SDRw/NBCU LUT

HLG Original SDR

HDR converted to SDRw/NBCU LUT

HLG Original SDR

HDR converted to SDRw/NBCU LUT

HLG Original SDR

Test PatternsSDR Bars

SDR converted to HDRw/NBCU LUT

SDR Original HLG

Example: SDR Content into HDR without proper conversion

very bright and over saturated

correct

HDR into HDR Display

SDR into HDR Display – without conversion (LUT)

Example: HDR Content into SDRwithout proper conversion

dim and undersaturated

correct

SDR into SDR Display

HDR into SDR Display – without conversion (LUT)

Example: SDR Content into HDR without proper conversion – Tech Explanation

very bright and over saturated

correct

SDR into SDR Display

SDR into HDR Display – without conversion (LUT)

SDR is BT.709 constrained to 709 triangle

Consistent energy throughout waveform

Example: HDR Content into SDRwithout proper conversion – Tech Explanation

correct

HDR into HDR Display

HDR into SDR Display – without conversion (LUT)

dim and undersaturated

HDR is BT.2020 Outside of 709 triangle

Bulk of the energy below 75% highlights above 75%