What calibration is
Calibrating a display means making it reproduce a known standard. The workflow is a loop: pick a target (a standard like BT.709 or sRGB), measure what the display currently does, correct it, and verify by measuring again. PatternSpace does not measure or auto-correct your display — it provides the precise, GPU-rendered patches the rest of the chain depends on.
Common reference targets include ITU-R BT.709 for HDTV parameters and BT.1886 for the HDTV reference display transfer function; BT.2100 specifies HDR television image parameters. These standards define targets, while a meter is still needed to measure how a particular display performs.
Where PatternSpace fits
A full calibration bench has three parts: a pattern source (PatternSpace), a meter (a colorimeter or spectrophotometer), and calibration software — such as ColourSpace or CalMAN — that reads the meter and computes a correction. That software drives PatternSpace over a pattern-generator protocol (ColourSpace's Network Protocol, CalMAN's UPGCI, the PGenerator TCP command set with UDP discovery, or the first-party PatternSpace Remote), and PatternSpace renders each requested patch on the target output so the meter can measure the display's actual response. See Connecting Calibration Software for each protocol. You can also use PatternSpace on its own to verify a display by eye or with a meter against an SDR Reference standard.
This loop is for macOS display output. Output presets, ICC assignment, and calibration curves do not act on DeckLink SDI output; for SDI, see DeckLink SDI and correct in the external monitor or LUT device.
- Profile the calibrated state. A profile's primaries and tone response must describe the display with its calibration curves active. Do not pair an uncalibrated tone response with curves that change it.
- Activate before re-measuring. Verify reads profile data only. Assign the checked profile in ICC Profiles → Display and confirm it is active. Live calibration applies the curves from the LUT imported in Build, not from the selected profile; with only an imported profile, load and confirm its curves with the tool that installs them.
- Standalone LUTs applied by a monitor, LUT box, or other software are not checked by Verify; load them in their destination and measure there.
Avoid the identity-transform trap
Color management converts from a source profile to the display profile. When they are the same, as with Device Native or content tagged with the display's own profile, nothing is converted. A numeric check through that path agrees with itself whatever the profile contains, so it cannot validate the profile. A meter reading through Device Native shows the display's current response, not how content in another color space is reproduced through the profile.
Use Device Native to characterize, and an SDR Reference preset to verify. PatternSpace's offline Verify refuses identity comparisons before converting, and flags any engine that returned its input values unchanged. Use the same SDR Reference preset for the numeric check and the meter check; checking an imported source profile is an offline diagnostic only. Background: Light Illusion's Mac colour management guide.
Getting it right
Set the output preset and signal range for the standard you are measuring, and keep the display state fixed during the run. After making a correction, activate it through the intended path and measure again; a software check alone does not establish optical accuracy.
- Match the target. Choose the Output Color preset for the step: Device Native to characterize the display, and the SDR Reference preset for the standard you are verifying. Verifying through Device Native is an identity trap.
- Turn HDR off for SDR work. Before an SDR measurement, disable HDR for the target display in macOS Display Settings — the app layer can't confirm the system HDR state for you, and leaving it on invalidates the result. See display setup.
- Don't double-encode range. Set Full or Legal range in one place only — either your calibration software or PatternSpace, never both.
- Turn corrections into a profile. A gamma correction can be exported as an ICC profile with a VCGT via the ICC profile tools, or applied live while you iterate — both require Pro.
- SDR first. This workflow targets SDR standards; HDR measurement uses dedicated Output Color presets covered in Display Setup.
Start calibrating
PatternSpace is a free download on the Mac App Store; network automation and advanced HDR output are PatternSpace Pro.
FAQ
Do I need a meter to calibrate?
To build a measured correction, yes — a colorimeter or spectrophotometer, read by calibration software. PatternSpace supplies the patches; it does not measure the display itself.
Can I use PatternSpace without extra software?
Yes, for verification: render SDR Reference patterns and check the display against a standard, or apply a calibration LUT you already have as a live VCGT (Pro).
Does this cover HDR calibration?
This guide focuses on SDR. HDR measurement uses dedicated Output Color presets (HDR PQ, Linear HDR) described in the Display Setup guide.
Why did my verification pass when nothing changed?
Probably because nothing was converted. If the source and the display profile are the same, as with Device Native, a numeric check agrees with itself. Verify with an SDR Reference preset into the display profile; PatternSpace's offline Verify refuses identity comparisons.