HDR Professional Standards & Best Practices 3 — Questions and Answers
Question 1: Which viewing environment standard does the Society of Motion Picture and Television Engineers (SMPTE) recommend for HDR content evaluation in a professional grading suite?
- SMPTE ST 431-2 (DCI dark room, 14 fL surround)
- ITU-R BT.2100 with 5% of peak white as surround lighting (Correct answer)
- ISO 3664 Graphic Technology viewing conditions
- SMPTE RP 431-2 with ambient luminance below 0.1 lux
Correct answer: ITU-R BT.2100 with 5% of peak white as surround lighting
ITU-R BT.2100 recommends a surround luminance of 5% of the reference white level for HDR evaluation environments.
Question 2: When creating a Hybrid Log-Gamma (HLG) master for broadcast, what is the key advantage of HLG over PQ for live production?
- HLG achieves higher peak luminance than PQ at all display brightness levels
- HLG is scene-referred and backward compatible with SDR displays without conversion (Correct answer)
- HLG requires less storage bandwidth than PQ-based formats
- HLG is mandated by Netflix and Amazon for all streaming deliverables
Correct answer: HLG is scene-referred and backward compatible with SDR displays without conversion
HLG's scene-referred nature means SDR displays can directly decode the signal without separate conversion, making it ideal for live broadcast where real-time SDR compatibility is critical.
Question 3: A client requests a 'P3 D65' color gamut deliverable. What does this specification mean?
- DCI-P3 primaries with a D65 white point, used in consumer HDR displays (Correct answer)
- Rec. 709 primaries with a D50 white point for print mastering
- BT.2020 primaries limited to 65% of the full gamut
- A custom wide-gamut profile used exclusively in Dolby Vision
Correct answer: DCI-P3 primaries with a D65 white point, used in consumer HDR displays
P3 D65 refers to the DCI-P3 color primaries paired with the D65 (6500K) white point, the standard used by Apple displays and many HDR consumer devices.
Question 4: What is the maximum bit depth specified by SMPTE ST 2084 (PQ) for HDR signal encoding?
- 8 bits
- 10 bits
- 12 bits (Correct answer)
- 16 bits
Correct answer: 12 bits
SMPTE ST 2084 specifies up to 12-bit encoding to represent the full PQ luminance range from 0.0001 to 10,000 nits with sufficient precision.
Question 5: Which professional practice helps prevent HDR banding artifacts in gradient regions during color grading?
- Reducing the output bit depth to 8 bits to force dithering
- Working in a floating-point color space such as ACEScct or linear light (Correct answer)
- Applying aggressive noise reduction before grading
- Clipping all values above 400 nits before export
Correct answer: Working in a floating-point color space such as ACEScct or linear light
Working in floating-point or high-bit-depth color spaces like ACEScct or linear light preserves precision in gradients, reducing quantization-induced banding.
Question 6: Under SMPTE ST 2094-10 (HDR10+), who is responsible for generating the dynamic metadata during post-production?
- The display manufacturer's firmware at playback time
- The colorist or mastering engineer using a compatible grading tool (Correct answer)
- The streaming platform's transcoder automatically
- The camera manufacturer via embedded sensor data
Correct answer: The colorist or mastering engineer using a compatible grading tool
SMPTE ST 2094-10 dynamic metadata is authored by the colorist or mastering engineer using a compliant grading tool, not generated automatically by the display or transcoder.
Question 7: A facility receives an HDR master that was graded on a 1000-nit display for a 4000-nit target. What professional step should they take before client approval?
- Approve it as-is since all PQ masters are interchangeable
- View the content on a display matching the target peak luminance or use a verified trim pass (Correct answer)
- Transcode to SDR and evaluate only the SDR version
- Apply a generic 4000-nit LUT without reviewing the result
Correct answer: View the content on a display matching the target peak luminance or use a verified trim pass
Evaluating content on a display that matches the target peak luminance (or using a verified trim pass) is essential to confirm the creative intent holds at the intended brightness.
HDR Professional Standards & Best Practices 3
Which viewing environment standard does the Society of Motion Picture and Television Engineers (SMPTE) recommend for HDR content evaluation in a professional grading suite?