# Gamut Scope

Gamut Scope flags pixels that lie **outside a target colour gamut** — the set of chromaticities a display can actually reproduce. A common use case is checking whether a Rec. 2020 / PQ (SMPTE ST 2084) HDR master stays inside the **P3-D65** gamut that real mastering and consumer HDR displays can show.

Gamut and transfer function are separate properties of a signal. "Rec. 2020" describes the **container primaries and white point** (chromaticity), while "PQ" / "HLG" describe the **EOTF** (how code values map to light). Gamut Scope checks the chromaticity side of that pair — the transfer function is handled by the waveform and HDR Limit QC.

It works in False Color mode — pixels within range are rendered in grayscale, pixels near the gamut edge are coloured orange, and out-of-gamut pixels are rendered in red:

<figure><img src="/files/I7qco6fqduP2DpT9BLS1" alt=""><figcaption></figcaption></figure>

You can also use Gamut Scope to monitor absolute luminance (nits) and set a maximum-brightness threshold:

<figure><img src="/files/V3g5nVEBd32TIhgR2fSt" alt=""><figcaption><p>Setting the threshold to 500 nits</p></figcaption></figure>

In the scope you can see which part of the image exceeded the given brightness:

<figure><img src="/files/7QUvLdYbGOaPaq3N8TiF" alt=""><figcaption></figcaption></figure>

## Why gamut mapping matters in HDR

A Rec. 2020 master can carry chromaticities no current mastering monitor can display. Most high-end HDR monitors cover \~95–99 % of **DCI-P3**, not Rec. 2020 — the extra Rec. 2020 volume exists as a *container* for the future. When such a signal reaches a P3-limited display the downstream tone/gamut mapper has to decide how to handle out-of-P3 pixels, and different players will make different choices. Finding those pixels in the grading suite lets the colourist make the call instead of the TV.

This is why mastering pipelines often grade to **P3-D65 ST 2084** limited inside a Rec. 2020 container — ensuring the image as graded will render predictably on today's hardware while still being future-proof.

## Directional Indicators (1.11.22+)

Directional arrows show which way colours would have to move — in chromaticity space — to return to the target gamut.

## Gamut Error Display (1.10.134+)

Gamut errors are highlighted for both SDR (Rec. 709 inside a wider working space) and HDR (P3 inside Rec. 2020) signals.

## Related

* [CIE Plot](/nobe-omniscope/scopes/cie-plot.md) — visualise the signal's actual chromaticity locus against the target gamut triangle
* [HDR Limit](/nobe-omniscope/qc/hdr-limit.md) — nit-level QC for HDR deliverables
* [Gamut Check](/nobe-omniscope/qc/gamut-check.md) — pass/fail QC rule variant


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.timeinpixels.com/nobe-omniscope/scopes/gamut-scope.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.