Originally Posted by lovingdvd
Correct. I think the trick is, as he later went on to post, that you have to take the color control down a lot (-30 I think he said), and then use the CMS controls to compensate. With hindsight this is probably what cine4home's early remarks were about when he talked about first calibrating overall saturation, you think?
Hi guys, I guess it's easier to follow the discussion here. Yes, I did manage to get a better result (I think) but it would be nice if some could confirm I'm heading in the right direction.
LovingDVD, I can confirm that it's really annoying when playing with the gamma steps, it does affect the neighboring ones. I found out two things:
1) a higher gamma makes it MUH MORE difficult to flatten the greyscae (at least for me), so I think I'm going to stick to 2.3 maximum (as a reference) which is probably going to end up as an average of around2.2 anyway.
2) When you look at the uncorrected RGB curve, try to minimise the points you're trying to correct. Initially, I tried to go step by step, and it just drove me mad. Then I started again, and tried to corect the big bumps first, to lower the average dE, then work down on the smaller bumps (if that makes sense). It may be a well known approach, but as I said, I'm learning...
Regarding going down to -30, it was a bold approach to test the theory (go much further than recommended to set the red at 21%, and then try to correct each color individually with the brightness control.
I have no idea if there is an inherent flaw in this theory, and someone more experienced may have a look at the uncorrected gamut and know instinctively how much to push the color and tint to get the right starting point for the primaries/secondaries, and then improve from there.
But it looks like the right approach at the moment. Before adjusting the brightness, I had all the primaries (including green) spot on, and only cyan outside. Of course Y was all over the place.
I am going to start again from scratch when I have a bit more time, following Tom's excellent guide and using the table for xyY in REC709 to try to get closer values (in my last attempt I didn't have the right percentages for Y and I just did alot of guesswork to bring dE down). I know, I should have started from there but I found the "calibration for dummies" at my level for greyscale, it was just not detailed enough for a proper CMS system...
From what I understand from Ekkehart's very vague descrition, he seemed to think that the approach to bring color way down to bring the primaries and secondaries inside the gamut, and then pushing them back towards the right point was the best approach (that's from the translation, my German is not good enough).
Hop this helps....