HDR Color Science & Dynamic Range 3 — Questions and Answers
Question 1: Which mastering display standard is commonly used to grade HDR content at 1000 nits peak luminance?
- SMPTE ST 2065
- P3-D65 with ST 2084 (Correct answer)
- BT.709 with gamma 2.4
- ACES AP0
Correct answer: P3-D65 with ST 2084
P3-D65 with the ST 2084 PQ transfer function at 1000 nits is a widely used mastering color space for HDR content.
Question 2: What is 'tone mapping' in HDR post-production?
- Assigning ACES color space to camera footage
- Converting HDR content to fit within the limits of a lower-dynamic-range display (Correct answer)
- Increasing the peak brightness of SDR content
- Applying a 3D LUT to transform gamut between color spaces
Correct answer: Converting HDR content to fit within the limits of a lower-dynamic-range display
Tone mapping is the process of remapping high-dynamic-range luminance values to fit within the narrower range of a target display or output.
Question 3: What is the approximate luminance of a typical SDR reference white in a broadcast mastering environment?
- 18 nits
- 100 nits (Correct answer)
- 400 nits
- 1000 nits
Correct answer: 100 nits
SDR mastering reference white is standardized at 100 nits (cd/m²) in a controlled broadcast grading environment.
Question 4: Which of the following color spaces has the largest gamut relative to human vision?
- sRGB
- DCI-P3
- BT.2020 (Correct answer)
- BT.709
Correct answer: BT.2020
BT.2020 has the widest color gamut of those listed, covering approximately 75.8% of the CIE 1931 color space, compared to ~35% for sRGB/BT.709.
Question 5: In HDR grading, what does 'MaxFALL' stand for?
- Maximum Frame Average Light Level (Correct answer)
- Maximum Floating Absolute Luminance Limit
- Maximum Full-Array Local Dimming Level
- Minimum Acceptable Frame Luminance Level
Correct answer: Maximum Frame Average Light Level
MaxFALL stands for Maximum Frame Average Light Level, representing the maximum average luminance value across all frames in a piece of content.
Question 6: What does a 'clip' in HDR grading indicate when reviewing a waveform monitor?
- The signal has reached 0 nits (pure black)
- The signal has exceeded the maximum encoded luminance value (Correct answer)
- The color gamut boundary has been exceeded
- The video has dropped below the noise floor
Correct answer: The signal has exceeded the maximum encoded luminance value
A clip on a waveform indicates the signal has hit the ceiling of the encoding system, losing detail in the brightest highlights.
Question 7: Which characteristic of human vision is exploited by HDR to create a more impactful image versus simply increasing average brightness?
- Simultaneous contrast and the perception of relative brightness differences (Correct answer)
- Absolute sensitivity to wavelengths above 700nm
- Equal sensitivity to luminance across the entire dynamic range
- Higher sensitivity to blue light than red light
Correct answer: Simultaneous contrast and the perception of relative brightness differences
The human visual system perceives brightness relatively, so HDR's wide contrast ratio between dark and bright areas creates a more impactful and realistic image than simply raising average luminance.
HDR Color Science & Dynamic Range 3
Which mastering display standard is commonly used to grade HDR content at 1000 nits peak luminance?