HDR Standards & Formats 3 — Questions and Answers
Question 1: What is the maximum signal level (in nits) that the HLG system is designed to represent at 100% signal value?
- 400 nits
- 1,000 nits
- 10,000 nits
- HLG is scene-referred and has no absolute nit ceiling (Correct answer)
Correct answer: HLG is scene-referred and has no absolute nit ceiling
HLG is a scene-referred system whose absolute brightness depends on display capability, not a fixed nit ceiling embedded in the signal.
Question 2: SMPTE ST 2086 defines metadata that describes which aspect of HDR mastering?
- Dynamic tone mapping curves for each scene
- Mastering display color volume including primaries, white point, and min/max luminance (Correct answer)
- Audio loudness normalization for HDR content
- Frame-rate conversion parameters for HDR streams
Correct answer: Mastering display color volume including primaries, white point, and min/max luminance
SMPTE ST 2086 specifies static metadata describing the mastering display's color primaries, white point, and luminance range.
Question 3: Which HDR format allows content creators to embed 'trim passes' that optimize appearance on displays with different peak luminance levels?
- HDR10
- HLG
- Dolby Vision (Correct answer)
- HDR10+
Correct answer: Dolby Vision
Dolby Vision supports creative trim passes—metadata overlays that tailor the image for displays at various brightness tiers (e.g., 600, 1000, 4000 nits).
Question 4: What does the acronym MaxCLL stand for in HDR metadata standards?
- Maximum Chrominance Luminance Level
- Maximum Content Light Level (Correct answer)
- Maximum Color Luma Limit
- Maximum Calibrated Luminance Level
Correct answer: Maximum Content Light Level
MaxCLL (Maximum Content Light Level) is the highest single-pixel brightness value in the entire HDR video stream, expressed in nits.
Question 5: In the context of HDR standards, what does 'electro-optical transfer function' (EOTF) describe?
- How the camera sensor converts photons to an electrical signal
- How the display converts a digital code value to emitted light (Correct answer)
- How the colorist adjusts saturation in post-production
- How audio is synchronized with HDR video
Correct answer: How the display converts a digital code value to emitted light
The EOTF describes the mathematical relationship between a digital signal code value and the luminance output of a display device.
Question 6: Which wide color gamut standard, often paired with HDR, covers roughly 75.8% of the CIE 1931 color space?
- sRGB
- DCI-P3
- Rec. 2020 (BT.2020) (Correct answer)
- AdobeRGB
Correct answer: Rec. 2020 (BT.2020)
Rec. 2020 (ITU-R BT.2020) covers approximately 75.8% of the CIE 1931 color space and is the target gamut for Ultra HD HDR content.
Question 7: Technicolor Advanced HDR (SL-HDR2) is notable for which capability compared to other HDR systems?
- It requires no metadata of any kind
- It is backward-compatible with SDR displays without a separate SDR version (Correct answer)
- It uses 16-bit encoding for all content
- It embeds HDR data in the audio track
Correct answer: It is backward-compatible with SDR displays without a separate SDR version
SL-HDR2 encodes HDR as a single-layer signal that SDR displays can decode natively, achieving SDR backward compatibility without dual streams.
HDR Standards & Formats 3
What is the maximum signal level (in nits) that the HLG system is designed to represent at 100% signal value?