What this inspector shows
| Field | What it means |
|---|---|
| Class | What the profile is for. Display profiles use mntr; device links use link. |
| Structure | Whether the transform is a matrix with tone curves (matrix/TRC) or a multidimensional LUT (A2B/B2A tags). |
| Primaries and white point | CIE x,y coordinates recovered from the colorant tags and the chromatic adaptation matrix (chad). Shown only for matrix/TRC profiles. |
| Tone response | The curve each channel uses: a gamma value, the sRGB curve, linear, a parametric curve, or a sampled table. |
| Calibration curves (VCGT) | Per-channel curves stored in the profile’s vcgt tag, if it has one and the data can be read. |
Stored curves are not active calibration
A vcgt tag stores calibration curves inside the profile file. This page reads those stored values. It cannot tell whether macOS has loaded them, or whether they are active on any display: other software and display changes can replace the active gamma tables at any time.
The inspector reports one of four states: no VCGT tag, readable curves, a VCGT form it does not read, or damaged data. Only readable curves are plotted.
New to VCGT? Read what VCGT is and how it differs from the TRC.
To check what is active on a display, use the Display tab of the ICC profile tools in PatternSpace for Mac, which reads the live gamma curves back. Display accuracy still requires measurement.
When you need more than an inspector
PatternSpace for Mac works with display profiles end to end, not just reading them.
- Build a matrix/TRC display profile from known primaries and tone response, or calibrate one from a
.cubeLUT. - Compare two profiles side by side.
- Verify a transform offline against Apple’s ColorSync engines.
- Assign a profile and read the active profile back.
Building, inspecting, and comparing profiles is free in the app. Exporting and assigning a generated profile, and temporary calibration, require PatternSpace Pro. Need a calibration LUT in Cube format first? Use the free online LUT converter.