Luminosity Limit

BETA - This feature is available in beta releases (1.11.x). Install the beta version from the downloads page to access it.

Luminosity Limit QC monitors your video signal for pixels exceeding configurable brightness thresholds. This is essential for broadcast compliance and ensuring your content meets delivery specifications.

Overview

The Luminosity Limit tool checks every frame for:

• Pixels exceeding maximum luminance levels

• Pixels below minimum luminance levels

• Both legal range and extended range violations

This is particularly important for:

• Broadcast delivery compliance (100 IRE limits)

• HDR content validation

• Avoiding clipping in final deliverables

Enabling the Tool

1. Open the QC panel (View > QC Panel or use the toolbar button)

2. Enable Luminosity Limit checkbox

3. Configure your threshold settings

How It Works

The Luminosity Limit tool analyzes each frame and:

1. Measures luminance values across all pixels

2. Compares values against your configured thresholds

3. Reports violations in real-time

4. Logs errors to the QC Timeline for review

Settings

Setting	Description	Default
Max Level	Maximum allowed luminance (IRE or nits)	100 IRE
Min Level	Minimum allowed luminance	0 IRE
Scale	IRE, Percent, or Nits (for HDR)	IRE
Error Threshold	Percentage of pixels to trigger error	0.1%
Warning Threshold	Percentage of pixels to trigger warning	0.01%

Scale Options

Scale	Use Case	Range
IRE	Standard broadcast (SDR)	0-109 IRE
Percent	General video work	0-100%
Nits	HDR content	0-10000 nits

Reading the Results

In the QC Panel

The QC panel shows real-time status:

• Green: All frames within limits

• Yellow: Warning threshold exceeded

• Red: Error threshold exceeded

Current statistics displayed:

• Maximum luminance detected

• Percentage of pixels over limit

• Frame count with violations

In the Timeline

Luminosity limit errors appear in the QC Timeline:

• Yellow markers: Warning-level violations

• Red markers: Error-level violations

• Click any marker to jump to that frame

In Exports

When exporting QC reports (EDL/HTML):

• Each violation is logged with timecode

• Peak luminance value is recorded

• Percentage of over-limit pixels is included

Use Cases

Broadcast Delivery

Most broadcasters require video to stay within legal range:

1. Set Max Level to 100 IRE (or per broadcaster specs)

2. Set Min Level to 0 IRE

3. Set Error Threshold to match delivery specs (often 0%)

HDR Mastering

For HDR content with specific peak brightness targets:

1. Switch Scale to Nits

2. Set Max Level to your target (e.g., 1000 nits for HDR10)

3. Use Warning Threshold to catch near-limit content

Super-White Detection

To find super-white content (100-109 IRE range):

1. Set Max Level to 100 IRE

2. Set Error Threshold very low (0.001%)

3. Review flagged frames individually

Standards Reference

Standard	Max Level	Notes
EBU R103	100 IRE	European broadcast
SMPTE RP 2077	100 IRE	US broadcast
HDR10	1000-4000 nits	Depends on mastering
Dolby Vision	Up to 4000 nits	Profile dependent
HLG	~1000 nits	Scene-referred

Tips

• Use the Error Logger scope alongside Luminosity Limit for detailed tracking

• Set conservative Warning thresholds to catch issues before they become errors

• Different broadcasters have different specs - always verify requirements

• For HDR, consider using HDR Limit QC for more comprehensive checking

Related QC Tools

• HDR Limit - Comprehensive HDR validation including MaxCLL/MaxFALL

• Gamut Check - Color gamut compliance checking

• Data Analyser - Detailed signal statistics

• HDR Statistics - MaxCLL and MaxFALL measurement