IVTechnical

Mastering, calibration, and the room.

Notes on how the work is made, mastered, and presented. Offered in service of the work, not as specification for its own sake.

— I —

On calibration.

Each Hall is mastered on a reference display calibrated to the Rec.2100 standard with a PQ transfer function. Calibration is a condition of authorship: the mastered file is a description of light that depends on the display being able to render it.

Where the viewer's display falls short of the reference, the work gracefully degrades — but it is not the same work. This is true of prints under unfamiliar lighting, and it is true here.

— II —

Mastering specifications.

Plates are delivered as 16-bit PQ-encoded files, mastered for defined peak luminance and a known viewing environment. The following is the standard mastering profile, applied unless the Hall states otherwise.

Container: JXL · AVIF · PNG (16-bit)
Colour primaries: Rec.2020 / BT.2020
Transfer: SMPTE ST 2084 (PQ)
Peak luminance: Up to 4000 nits · per-Hall
Reference white: 203 nits, diffuse
Bit depth: 16-bit, linear ACEScg working space
Tone mapping: Per-Hall, declared in the mastering note
SDR fallback: HLG and a 100-nit SDR mix, served on capability detection

— III —

Display recommendations.

TheHall is best read on a calibrated reference monitor or a recent OLED panel capable of rendering the PQ transfer accurately. The following are not requirements but conditions under which the work is most fully visible.

Panel: OLED or reference LCD with local dimming
Peak luminance: ≥ 1000 nits sustained, ≥ 1500 nits peak
Black level: ≤ 0.005 nits
Colour volume: ≥ 95% DCI-P3, ≥ 75% Rec.2020
Calibration: D65, ΔE ≤ 2, PQ EOTF verified
Viewing environment: Dim ambient, ≤ 5 lux, off-axis sources controlled
System: HDR enabled at OS level, browser PQ pass-through verified

— IV —

The PQ workflow.

Plates are composed in linear ACEScg and mastered to Rec.2100 PQ. The mastering pass is non-destructive: highlights are preserved through composition, and only at the final step is the image encoded against the display's transfer function.

For rendered plates, lighting is authored in the same linear workspace and the same display reference. For photographic plates, scene-referred capture is preserved through to the final encode; no SDR intermediate is introduced.

— V —

On the room.

A display is not separable from its room. Ambient light, viewing distance, the temperature of nearby surfaces — these are part of the work's condition. The recommended posture is that of a small cinema: dim, attentive, undistracted.

— VI —

Fallback.

Where HDR cannot be served, a 100-nit Rec.709 fallback is provided. It is not the work, but it is a record of it.