On Jun 6, 2014, at 6:27 PM, John Gnaegy <gnaegy@apple.com> wrote:
That profile is only relevant to my display, it only describes the variation between my display and some theoretical ideal.
Just a nitpick: there isn't any "theoretical ideal" in the process, any more than there's a "theoretically ideal" throttle position in your car for 55 mph on a flat surface with no wind. So long as there aren't any discontinuities (i.e., instances where a larger number causes a dimmer output) and so long as the desired white point lies within the display's gamut and so long as there're enough bits for the resolution you want, anything else is equally valid. As a practical matter, the closer R=G=B=255 is to your desired white point, and the closer equal RGB values are to the neutral axis for that white point and spaced for the desired encoding gamma, the more likely the profiling software will be able to create an highly accurate characterization of the display and thus create an high quality profile. That's what calibration is designed to do: adjust voltages (perhaps manually with knobs according to on-screen guidance) or DAC lookup tables or that sort of thing so that a neutral evenly-spaced gray ramp sent down the display cable would actually look like a neutral evenly-spaced gray ramp. But even if you skip the calibration and go straight to profile construction, the profile will take care of mapping the actual neutral axis to whatever unequal RGB values are needed and so on. The profile will be more prone to banding or other quality-degrading artifacts, but that's an implementation problem and not a theoretical one. Cheers, b&