HDR (High Dynamic Range) expands the range of brightness and color a display can show, revealing detail in highlights and shadows that SDR clips. It relies on higher bit depth (usually 10-bit), a wide color gamut (Rec. 2020 container), and metadata that tells the display how to map the content’s brightness to its own capabilities. The formats differ mainly in how that metadata works.
The four formats
| Format | Metadata | Bit depth | Where you’ll see it |
|---|---|---|---|
| HDR10 | Static (whole title) | 10-bit | Open standard; near-universal baseline |
| HDR10+ | Dynamic (per scene/frame) | 10-bit | Samsung-led; royalty-free |
| Dolby Vision | Dynamic (per scene/frame) | up to 12-bit | Licensed; premium streaming/cinema |
| HLG | None (self-describing) | 10-bit | Broadcast / live |
Static vs dynamic metadata
- Static (HDR10) sets one mastering brightness reference for the entire program. Simple and universal, but a single tone-mapping curve must fit both the darkest and brightest scenes.
- Dynamic (HDR10+, Dolby Vision) adjusts tone mapping scene-by-scene or frame-by-frame, so each moment is optimized for the display. Better results, more complex pipeline.
- HLG (Hybrid Log-Gamma) needs no metadata: one signal renders acceptably on both SDR and HDR displays, which is why broadcast and live production favor it.
Transfer functions
HDR uses a different EOTF (electro-optical transfer function) than SDR’s gamma curve:
- PQ (SMPTE ST 2084) — absolute brightness, used by HDR10, HDR10+, and Dolby Vision.
- HLG — relative brightness, backward-compatible with SDR displays.
What a system needs to carry HDR
- HDMI 2.0a or later — 2.0a added HDR10, 2.0b added HLG. Dynamic HDR (HDR10+/Dolby Vision) is a feature of HDMI 2.1. See HDMI Versions.
- HDCP 2.2 — protected HDR content requires it end-to-end. See HDCP.
- Enough bandwidth — 10-bit color costs ~25% more than 8-bit. At 4K60 over an 18 Gbps (HDMI 2.0) link, HDR usually means dropping to 4:2:2 or 4:2:0 chroma. See Chroma Subsampling.
- EDID that advertises HDR — the display must signal its HDR support, or the source outputs SDR.
Common failure modes
- Washed-out or overly dark image. HDR metadata is being stripped by an extender/switcher, so the display shows the HDR signal without tone mapping (or falls back to SDR incorrectly).
- No HDR badge on the display. A device in the chain doesn’t pass the HDR EDID/metadata, or the link lacks bandwidth for 10-bit.
- Dolby Vision drops to HDR10. The path isn’t fully Dolby Vision-capable end-to-end.
Rule of thumb
HDR is a whole-chain property: source, cable, every extender/matrix, and the display must all support the format and have the bandwidth for 10-bit color. Any weak link silently drops you to SDR.
Related
Sources
- ITU-R BT.2100 — image parameter values for HDR TV, defining the PQ and HLG transfer functions.
- ITU-R BT.2020 — wide-gamut (Rec. 2020) colour container used by HDR.
- SMPTE ST 2084 — Perceptual Quantizer (PQ) EOTF used by HDR10, HDR10+, and Dolby Vision.
- ANSI/CTA-861 — HDR static and dynamic metadata signaling over HDMI.
- Dolby Vision and HDR10+ — vendor specifications for dynamic-metadata HDR.