Originally Posted by madshi
The better solution would be to do more than 9x9x9 measurements. E.g. ArgyllCMS in "ultra quality" mode measures and afterwards refines the grayscale at 128 measurement points, IIRC. The refinement is repeated until a certain error threshold is met. Afterwards it does several thousand color measurements spread over the 3D color space in such a way to maximize usefulness for human perception. In the final step ArgyllCMS converts all this information into a big 3dlut.
I can definitely see the benefit of more measurements, though that's of course a case of dramatically increased time/effort vs diminishing returns.
That is exactly the purpose of a 3dlut: Making a display conform to a specific target colorspace. The usefulness of this is not limited to LED projectors. There are many other display types which have a non-linear behaviour, too. There's also the problem with the gamma response. Ok, the Radiance has separate controls for that. With a 3dlut as big as that used by the eeColor and madVR, you can do color and gamma corrections in one step in the 3dlut. When using a 5x5x5 or 9x9x9 3dlut, you have to do gamma corrections separately. Of course that works, too, but taking more measurements and correcting everything via 3dlut seems a more complete solution to me...
Well that's not really what I meant, normally you use a CMS to map input values to calibrate to a known standard, eeColor's claim to fame is, well a few things, one of the first uses was with the TruVue Vango LED projector. That projector (like most projectors) had a huge gamut, way larger than BT.709, the eeColor box would map a BT.709 source to use that full, native LED gamut, stretching the gamut, but in such a way that things like skin tones/grass/etc aren't affected (don't look wrong). Vs without the eeColor box where you'd have the same output gamut, but you'd have skin tones stretched too red for example.
It also would do things like "compensate" for poor room lighting conditions.
Of course the value of those options is debatable, but do do that you need more than 9 points to "protect" what they call "memory colors".