Mastering Display Metadata: SMPTE ST 2086
SMPTE ST 2086 describes the color primaries, white point, and luminance range configured for the mastering display.
A source report might contain this mastering-display record:
| Field | Illustrative value |
|---|---|
| Primaries | P3 coordinates |
| Reference white | D65 |
| Minimum luminance | 0.005 nit |
| Maximum luminance | 1,000 nits |
SMPTE ST 2086 describes the configured color volume of the display on which the finished image was judged. Read the record as mastering context, not as a measurement of each frame.
Interpret the two apparent mismatches
The video uses BT.2020 primaries. That can coexist with P3 mastering primaries. The image was graded within one display's capabilities and expressed for delivery using a larger coordinate space. The two records name different stages. Correct coordinate conversion preserves the intended colors.
MaxCLL is below 1,000 nits. The mastering display could support a highlight brighter than any used in the actual sequence. Content-light metadata describes that sequence under its definition, while ST 2086 records the configured display range. The numbers need not be equal.
The minimum field likewise describes the mastering reference's lower luminance limit. It does not imply that every dark pixel reaches that level, or predict the black floor of the television currently showing the movie.
Use the record during adaptation
A renderer can use the reference volume as one input when deciding how to fit the produced image to a different output. The metadata supplies primary coordinates, white point, and luminance endpoints. It does not specify a complete transfer function or a sequence of shot-specific creative trims.
During an Emby comparison, keep this source record beside the actual delivered signal and display target. A display with another volume can use tone mapping and color adaptation. The record explains the source reference; the playback path determines how that reference is used.