Dolby Vision is Dolby's proprietary HDR video format — the one you'll see called out by name on streaming service badges, TV boxes, and Blu-ray cases, usually right next to (or instead of) HDR10. It's built on the same underlying transfer function as HDR10 — PQ, SMPTE ST 2084 — but adds something HDR10 doesn't have: metadata that changes over the course of the video instead of staying fixed.
Static metadata vs. dynamic metadata
A baseline HDR10 stream carries one set of brightness metadata (MaxCLL and MaxFALL — the maximum content light level and maximum frame-average light level) for the entire piece of content, start to finish. That's a real limitation: a movie with one blindingly bright sunrise shot and one dim, moody interior scene gets tone-mapped using the same numbers for both, because the display has no way to know the two scenes are that different.
Dolby Vision carries metadata that can change scene by scene, or even frame by frame, describing how that specific content should be tone-mapped for the specific display showing it. In principle, that means each shot gets treated on its own terms instead of being squeezed through one compromise curve for the whole runtime.
The cost of that precision
Dolby Vision isn't an open standard. Studios pay to master content in it, device makers pay to license decoder support, and the whole pipeline — camera, post-production, delivery, display — has to be Dolby-certified to carry the name. HDR10 is royalty-free and universally supported by comparison, which is exactly why it's the mandatory baseline for UHD Blu-ray and most streaming HDR, with Dolby Vision layered on top as an optional, premium addition where a studio and platform have both paid for it.
HDR10+ exists for the same reason, without the license fee
Samsung and Amazon co-developed HDR10+ specifically as a royalty-free answer to Dolby Vision's dynamic metadata — same core idea (per-scene tone-mapping instructions on top of a PQ signal), open format instead of licensed. Support for it is narrower than either HDR10 or Dolby Vision, but it exists precisely because dynamic metadata was worth having without the certification overhead.
Where this fits with what Headroom actually does
Everything on this site is about still images, not video, and about gain-map HDR specifically — the same family of ideas as Ultra HDR and Adobe's Gain Map spec, not Dolby Vision or HDR10. If you're trying to understand what's actually inside an HDR photo you already have, start with what a gain map is, not with video HDR terminology — the two live in genuinely different parts of the HDR landscape.