HDR — High Dynamic Range

High Dynamic Range

For display specification and brightness requirements, see video/flat-panel-displays. For HDMI signal transport of HDR, see signal-types/hdmi.

HDR (High Dynamic Range) video describes a signal with a greater luminance range and wider color gamut than standard dynamic range (SDR). Where SDR is mastered to a peak of 100 nits with Rec. 709 color, HDR content is mastered to 1000–10,000 nits with DCI-P3 or Rec. 2020 color. The result — when the display is capable — is more realistic specular highlights (sunlight, reflections, flames) and deeper shadow detail simultaneously. In installed AV, HDR is relevant when specifying 4K displays, routing 4K HDMI signals, and ensuring the signal chain supports the required HDR metadata standard.

HDR Standards

HDR10 is the baseline standard supported by all HDR displays and content platforms. If designing for HDR, HDR10 compatibility is the minimum requirement. Dolby Vision and HDR10+ require platform-specific licensing and display chipsets.

HLG is important for broadcast and live sports production. HLG signals are backward compatible with SDR displays (they produce a reasonable SDR image without tone-mapping) and do not require metadata. It is the standard for ATSC 3.0 broadcast HDR.

HDMI HDR Transport

HDR metadata and expanded color are carried within the HDMI signal via:

• Dynamic Range and Mastering InfoFrame (DRMI) — carries SMPTE ST 2086 metadata (peak luminance, color primaries) for HDR10
• Colorimetry — EDID extension block flags BT.2020 and DCI-P3 support
• Deep Color — HDR10 requires 10-bit color depth minimum (vs. 8-bit for SDR); HDMI 2.0 supports 10-bit at 4K60 4:4:4

For 4K HDR60 at full 4:4:4 color, HDMI 2.1 (48 Gbps) is required. HDMI 2.0 (18 Gbps) supports 4K HDR60 at 4:2:0 chroma subsampling (sufficient for most content delivery) or 4K HDR30 at 4:4:4. Verify that every device in the chain (source, switcher output card, extender, display input) supports the required HDMI version and color subsampling.

Signal Chain Requirements for HDR

For HDR to reach the display correctly, every link must pass HDR metadata without stripping it:

1. Source outputs HDR10 with ST 2086 InfoFrame
2. Switcher/matrix passes InfoFrame (not all older switchers do — verify)
3. HDBaseT extender or AV-over-IP encoder preserves metadata
4. Display input processes and applies tone mapping

If any device in the chain strips the HDR InfoFrame, the display receives the expanded luminance signal without tone-mapping instructions, often producing a washed-out or oversaturated image.

HDR in AV Installations

For most installed AV (conference rooms, boardrooms, corporate displays), HDR is a secondary consideration — the content being displayed (PowerPoint, video calls, web browsers) is SDR. HDR matters primarily when:

• 4K UHD playback from streaming services or 4K Blu-ray is in scope
• Broadcast integration — bringing in live HDMI/SDI feeds from cameras or broadcast equipment
• Digital signage with HDR-mastered content on high-brightness displays
• Premium boardroom or screening room where content quality is a specification requirement

When HDR is in scope, specify display peak brightness ≥ 600 nits minimum (with local dimming) for HDR10 to be perceptible. Displays rated below 400 nits with no local dimming cannot meaningfully render HDR content — they simply tone-map the signal to SDR range.

Common Pitfalls

• HDR InfoFrame stripped by an intermediate switcher. The source sends HDR10 metadata, but the switcher's output card does not pass HDMI InfoFrames, so the display receives the signal with no tone-mapping instructions and renders it incorrectly. Fix: verify switcher and extender firmware supports HDR InfoFrame passthrough (check release notes for "HDR support" or "InfoFrame passthrough"); update firmware if needed.

• Display EDID not advertising HDR support. The EDID's HDR static metadata block (from CEA-861.3/CTA-861-G) must flag supported EOTF (Electro-Optical Transfer Function) values — specifically SMPTE ST 2084 for HDR10. If the EDID does not advertise this, the source will not send HDR output even to an HDR-capable display. Fix: check display EDID with an EDID reader; if HDR metadata block is missing, update display firmware or use an EDID editor to add the block.

• HDR on a display too dim to render it meaningfully. A 300-nit SDR display passes the HDR signal but tone-maps it to SDR range, producing slightly different (not better) results than a native SDR signal. This is not harmful but creates false expectations. Fix: educate clients on display brightness requirements for perceptible HDR; specify appropriately bright displays when HDR content is a stated requirement.

• HDMI 2.0 cable failing at 4K HDR60 4:4:4. 4K HDR60 4:4:4 requires 18 Gbps, at the limit of HDMI 2.0. Marginal cables or connectors that work at 4K SDR may fail at this data rate. Fix: use Premium High Speed HDMI certified cables (tested to 18 Gbps) for 4K HDR runs; test with actual content, not just a test pattern.