HDR Limit
HDR Limit QC provides comprehensive High Dynamic Range content validation, ensuring your HDR material meets delivery specifications for various HDR formats and platforms.
Overview
The HDR Limit tool monitors:
Peak luminance per frame, in absolute nits (for MaxCLL compliance)
Frame-average luminance over the whole content (for MaxFALL compliance)
Optionally, that the signal decodes cleanly through the active EOTF (no out-of-range PQ / HLG code values)
This is essential for:
HDR10 and HDR10+ mastering (static and dynamic PQ metadata)
Dolby Vision deliverables (PQ base layer plus per-scene L1–L8 metadata)
HLG broadcast content (ARIB STD-B67 scene-referred transfer)
Streaming platform ingest requirements (Netflix / Disney+ / Apple TV+ / Amazon / YouTube)
Enabling the Tool
Open the QC panel (View > QC Panel or use the toolbar button)
Enable HDR Limit checkbox
Select your target HDR format
Configure threshold settings
How It Works
HDR Limit performs per-frame analysis:
Decodes the signal through the inverse EOTF (SMPTE ST 2084 for PQ, ARIB STD-B67 for HLG) to obtain per-pixel display luminance in candelas per square metre (nits). HLG additionally applies the system gamma tied to a chosen nominal peak (default 1 000 nits).
Computes per-pixel luminance (Y) — the scalar quantity metadata specs reference for MaxCLL / MaxFALL. Two methods exist in the industry:
Max-RGB — take the maximum of the three linear channels per pixel. Used by Dolby's original Dolby Vision analysis and by most HDR10 mastering tools.
CIE Y — compute a properly weighted sum of the linear R, G, B values (the active colour space's Y coefficients). Closer to perceptual brightness. Check your target spec — MaxCLL/MaxFALL as CTA-861.3 defines them reference a luminance of a pixel, and different tools interpret this slightly differently.
Tracks the per-frame maximum (for MaxCLL) and the frame average (for MaxFALL).
Compares against format-specific limits.
Logs violations to the QC Timeline.
Settings
HDR Format
Target HDR specification
HDR10
Max Peak (nits)
Maximum peak brightness allowed
1000
Max Average (nits)
Maximum frame average (MaxFALL)
400
Error Threshold
Pixel percentage to trigger error
0.1%
HDR Format Presets
HDR10 (1000 nits)
1 000
400
Most common HDR10 mastering-display peak; matches Netflix/Amazon reference.
HDR10 (4000 nits)
4 000
1 000
"Premium" HDR10 — Sony X300 / Dolby PRM-4200 class mastering.
Dolby Vision
4 000
1 000
Dolby Vision carries a mastering display metadata tag (e.g. Mastering Display 1000,0.005 or 4000,0.005). Targets depend on the mastering display actually used.
HLG
1 000
400
HLG is scene-referred: the code values themselves don't commit to a peak-nit target, but the display's system gamma maps to a nominal peak (usually 1 000 nits at reference).
Custom
User-defined
User-defined
Manual settings
HDR10 vs HDR10+ vs Dolby Vision. All three use PQ as their base transfer function and Rec. 2020 as their container. The difference is the metadata layer: HDR10 ships a single static pair of MaxCLL/MaxFALL values per title; HDR10+ adds dynamic per-frame tone-mapping metadata (SMPTE ST 2094-40); Dolby Vision adds its own dynamic per-shot L1–L8 metadata (SMPTE ST 2094-10 / profile-specific). Dolby Vision's L1 metadata — min, avg, max luminance per shot — is exactly what HDR Limit QC computes.
Reading the Results
In the QC Panel
Real-time display shows:
Current Peak: Maximum nits in current frame
Max Peak: Highest peak seen in session
Current Average: Frame average luminance
MaxFALL: Running content average
Status: Pass/Warning/Error indicator
In the Timeline
HDR limit violations appear as:
Yellow markers: Approaching limits (warning)
Red markers: Exceeding limits (error)
Hover for details including peak nits value
In Exports
QC reports include:
Timecode of each violation
Peak brightness value
Whether MaxCLL or MaxFALL was exceeded
Frame-by-frame statistics
Use Cases
HDR10 Mastering
Validate content for HDR10 delivery:
Select HDR10 (1000 nits) preset
Enable MaxFALL tracking
Run full content playback
Review any flagged frames
Streaming Platform QC
Different platforms have different requirements:
Netflix
1000-4000 nits
Content dependent
Amazon
1000-4000 nits
HDR10/DV supported
Apple TV+
Up to 4000 nits
Dolby Vision preferred
YouTube
1000 nits
HDR10 support
Broadcast HDR (HLG)
For HLG broadcast delivery:
Select HLG preset
Set Max Peak to broadcaster requirement
Enable average brightness monitoring
Verify against delivery specs
Understanding HDR Metrics
These are defined in CTA-861.3 as HDR static metadata type 1, carried in the SEI / mastering-display-metadata fields of the stream.
MaxCLL (Maximum Content Light Level)
The luminance value of the single brightest pixel in the whole content, in nits. Think of it as "the peak of peaks". HDR Limit tracks this across the session and reports the highest value encountered. MaxCLL feeds the downstream tone-mapper: a TV with a 600-nit panel seeing MaxCLL = 1 000 will compress highlights from 600–1 000 down to the panel's peak without crushing midtones.
MaxFALL (Maximum Frame Average Light Level)
The frame whose average linear luminance is highest, reported in nits. "Average" here is computed over the active picture area. MaxFALL is the knob that tells a consumer display how aggressively to defend itself against sustained full-field brightness (to protect the panel, especially on OLEDs that dim the whole screen under heavy load). A low MaxCLL with a high MaxFALL is a bright, uniform scene (a snowfield). A high MaxCLL with a low MaxFALL is a dark scene with one hot specular highlight (a lightbulb at night).
Why Both Matter
Consumer displays use MaxCLL/MaxFALL to drive their tone-mapping curves
Wrong values cause visible errors — crushed highlights (MaxCLL too low), panel dimming kicking in at the wrong level (MaxFALL wrong)
Streaming platforms require the static metadata to be truthful; incorrect tags fail ingest QC
Dolby Vision's per-scene L1 metadata (min / avg / max) plays the same role at a finer granularity — 24 frames instead of "the whole title"
Standards Reference
HDR10
PQ (ST 2084)
CTA-861.3 static
1 000 – 4 000 nits
400 – 1 000 nits
HDR10+
PQ (ST 2084)
ST 2094-40 dynamic
Per-scene
Per-scene
Dolby Vision
PQ (ST 2084)
Dolby L1–L8 (ST 2094-10) per-shot
Up to 4 000 nits (Profile 5/7/8)
Per-shot
HLG
ARIB STD-B67
No static tone metadata
~1 000 nits at reference
~400 nits
All four use Rec. 2020 as the colour container. Chromaticity rarely exceeds P3-D65 in practice because current mastering displays don't cover more than ~99 % of P3.
Tips
Always verify delivery specs with your distributor
Use HDR Statistics scope for detailed MaxCLL/MaxFALL measurement
Test problematic frames in the False Color scope with HDR preset
Consider headroom - staying below 90% of limits is good practice
Related QC Tools
Luminosity Limit - General brightness limit checking
HDR Statistics - MaxCLL/MaxFALL measurement
Gamut Check - Color gamut compliance
Data Analyser - Detailed signal analysis
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