Am 07.07.2019 um 16:33 schrieb THOMAS A LIANZA via colorsync-users:
Communication is possible to nearly all displays using some level of the DDC 2.0 specifications.
Not always very reliable though, and the DDC specification(s) lack consistent implementations, which seems to prevent general applicability (i.e. to me it looks like calibration software vendors are mostly forced to support DDC capable displays individually and often cannot rely on a common set of capabilities or even instruction sets).
A wide gamut panel will necessarily have an input lookup table, a matrix or 3D out, followed by a display look up table.
While a matrix or 3D LUT is not a requirement, it's surely nice-to-have for supporting things like an sRGB mode, and/or "advanced" calibration, inside the display itself.
In general, use of the graphic card LUT is not recommended at all in most modern calibration environments.
Well, we'd need to define "most". My definition of "most" with regards to (computer) display calibration would encompass typical desktop systems which either run a version of Windows (very common), macOS (less common) or an open source desktop (e.g. GNOME/KDE, even less common) paired with a run-of-the-mill LCD monitor. Unless Microsoft (same as Apple) decides to no longer support setting graphics card 1D LUTs ("videoLUT") via OS APIs, I don't see this functionality going away anytime soon, and it is still the main functionality that most calibration packages are relying upon (due to widespread support across different platforms).
If a display has an HDMI interface, the graphic card LUT is normally inaccessible because there are a number of assumptions about the display color management.
Hmm. My own experience thus far has been that the actual physical connection or even interface seems to be irrelevant regarding whether or not typical videoLUT functionality will be available. The only requirement really is that support for the respective generalized OS APIs is implemented at the graphics driver level (and there are some USB3 external "graphics cards" which indeed seem to not implement it). Whether that means actual hardware LUTs, or emulated in software, is up to the implementation.
The current processes generally calibrate the displays to a given color space and use a very simple ICC profile to describe the display setup.
This assumes rather high-end display hardware though, that not everyone owning a calibration device will have access to (certainly more common in professional or semi-professional environments).
As the industry moves towards HDR (high dynamic range) and Wide Gamut, calibration occurs in the display, not on the driving platform.
It may be a bit too early to anticipate, but FreeSync2 HDR which is (imho) quite likely to see some adoption (with even major LCD TV vendors onboard) seems to move in the opposite direction, with most or all HDR processing delegated to the graphics hardware in the connected system(s).
The ICC profile is used as a container for other information in HDR systems in Windows 10.
AFAIK, videoLUT still applies in HDR mode, although personally I currently have no ability to check, lacking a HDR-capable display. Cheers, Florian Höch