Which display can I calibrate: built-in, external, or reference?
PatternSpace outputs to any display macOS lists: a Mac’s built-in screen, a wired external monitor or TV, or an AirPlay display (for layout checks only, because AirPlay video is compressed). Pick it in the Output Display selector below. For a reference display fed from a DeckLink device, use the separate DeckLink SDI output instead; see the DeckLink SDI guide.
Choose the output display
The Output Display selector lists every connected display; pick the one you're calibrating and the patch window opens there at full resolution. If it's your only display, PatternSpace collapses to a menu-bar item so controls don't obstruct the patch. Connected displays appear grouped by connection — Built-in, Wired, or AirPlay.
Output Color
Output Color decides how PatternSpace encodes patch colors for the panel. Pick the preset that matches the standard you're measuring:
- Device Native — raw patch code values through a profile-identity layer. Use when profiling or measuring the display itself. Free.
- Display SDR — a clean, display-relative SDR path with no extended-range color. Free.
- SDR Reference presets — decode through a standard's transfer function and gamut: Web (sRGB); Photography (Adobe RGB, P3-D65, ProPhoto); HDTV (BT.601, BT.709 γ2.2/γ2.4/BT.1886); UHD (BT.2020); Cinema (P3-DCI, P3-D65). Free.
- HDR PQ — No Tone Mapping (P3-D65, BT.2020) — PatternSpace decodes normalized ST 2084 / PQ values itself and reports hard-clip diagnostics; use these for deterministic EOTF verification. Requires EDR headroom and Pro.
- HDR PQ — tone-mapped (P3-D65 ST 2084, BT.2020 ST 2084) — macOS interprets and tone-maps the PQ signal to the display. Do not use for deterministic EOTF verification (macOS owns the interpretation, hard-clip diagnostics are omitted). Requires EDR headroom and Pro.
- Display HDR / Linear HDR presets — extended-range HDR relative to the display or in linear light; Peak White appears for the linear-HDR family. Requires EDR headroom and Pro.
The catalog includes 14 SDR Reference presets. For the standards behind common video targets, see the ITU-R recommendations for BT.709, BT.1886, and BT.2100.
For SDR measurement, turn HDR off first. Before measuring with Device Native or an SDR Reference preset, disable HDR for the target display in macOS Display Settings. The app-layer path is not a substitute for confirming the system HDR state — leaving HDR on can invalidate an SDR measurement. For Device Native measurements, also establish the intended active calibration state; the profile description and gamma ramp are separate (see below).
Measurement range
Full emits normal full-range values; Legal remaps to video range at the source bit depth. Enable legal encoding in your calibration software or PatternSpace — never both. Legal applies to Device Native external patches and SDR Reference output; HDR PQ and Linear HDR stay Full.
Display details
The ⓘ button by the display name reports:
Color profile
The ICC profile or color-gamut name (e.g. Display P3 or sRGB).
Max & current EDR
Peak EDR headroom under ideal conditions, and the actual headroom right now — lower when throttled or when another HDR app competes.
Peak White
The effective peak white after OS clamping; if macOS reduced it, both figures are shown (e.g. "2.20 EDR, clamped from 3.00").
Connection
How the display is attached: Built-in, Wired, or AirPlay.
EDR and Peak White
On EDR displays, set Peak White to the target nit level divided by the display's SDR white luminance — for a 1000-nit target on a 100-nit SDR white, set 10.0. The ceiling is the display's current EDR, which macOS lowers (sometimes to 1.0×) at high brightness or under thermal throttling. If Peak White seems to do nothing, lower display brightness to regain headroom.
Some EDR displays can provide up to 16× headroom, but the current value can be lower as brightness, thermal conditions, reference mode, or competing HDR content changes. Apple describes EDR headroom as a ratio to SDR white in its current-headroom documentation. PatternSpace’s value describes available rendering headroom; it is not a measurement of the display’s calibrated luminance.
AirPlay
macOS starts AirPlay from the system, not the app: open Control Center → Screen Mirroring, pick the Apple TV, and set Use As → Extended Display (not Mirror). AirPlay video is compressed, so use it for layout and workflow checks only. Connecting an Apple TV by HDMI does not remove compression from a Mac-to-Apple-TV AirPlay stream. Use a verified generator path for color-critical work.
A profile's tone-response curve describes the display; VCGT is separate calibration data. Selecting a profile with a neutral TRC does not prove an existing gamma ramp has been cleared. Device Native does not bypass an active ramp. Establish the intended state and verify it before profiling. See the ICC and VCGT workflow.
Output Check and Signal Details
PatternSpace 2.3 adds two read-only diagnostics for reviewing the output path. Open Output Check from the Output menu or output card to review the selected display or SDI target, signal configuration, assigned profile, calibration tag, HDR headroom and gamma-table observation. Record your brightness/reference-mode and automatic-adjustment assumptions. Manual answers are user reports, not system measurements; switching apps expires their review. Refresh after changing an external profile or gamma table.
Signal Details separates received source values, the app mapping, prepared or emitted SDI software frames, and the physical signal. Historical observations stay visibly labeled. Opening, refreshing, copying or exporting observations does not send a patch. Copy Summary and Export Snapshot omit connection authorization and identifying diagnostic text.
Choose the source bit depth, range and one diagnostic sample, then send it explicitly. Local probes require available output without an active controller; probes from a connected JSON controller require host authorization. If configuration or ownership changes, refresh and retry explicitly. Cancel prevents unsent work; a submitted sample may still appear. Host admission and presentation evidence are separate. Physical HDMI/SDI values and bit-perfect accuracy require external capture.
PGenerator requests retain the received integers and declared bit depth separately from the effective renderer input, which follows the existing normalization. JSON values are received normalized numbers; any integer code equivalents are labeled as calculated, not as received values.
Where to next
- Calibration Workflow — how measure → correct → verify fits together, and where these presets slot in.
- Connecting Calibration Software — drive PatternSpace from ColourSpace, CalMAN, PGenerator, or PatternSpace Remote.
- ICC Profile Tools — build, calibrate, inspect, compare, and assign display profiles.
Set up your display
PatternSpace is free on the Mac App Store; HDR output presets and Peak White are PatternSpace Pro.
