Originally Posted by dsinger
Perhaps it has something to do with the Lumagen Radiance I use for calibration, but I have calibrated with LD off, LD on and IVC low on thru the entire process. Turning IVC low on after calibrating with LD off or LD on obviously increases the white output considerably (roughly from 30 FL to 48 FL at 100%) but the gamma numbers, greyscale de's and gamut de's don't change. Measured before and after numerous times to make sure no harm done with IVC low on. Finally got to the point where I just leave IVC low on for calibration. Note that these are manual calibrations using Chromapure and a Chroma 5 Pro.
We sure have different behaving displays!
Do you calibrate both the Elite & Radiance or just the Radiance? I also have a Radiance XD but these changes are on the Elite and will alter not just the gamma curve. I use CalMAN and a C6 meter. I do 10 point grayscale and saturation sweep calibration at 25, 50, 75 and 100% saturation on the Elite. I then do 21 point grayscale and 3D 125 point Cube LUT on the Radiance.
You want to tell me you get the same exact gamma curve whether you use LD or IVC low? That makes no sense. That's exactly what IVC is primarily affecting and why it looks different. But there are side effects.
It also alters the gamut readings because the luminance levels have changed across the board. not just the white level. The RGB tracking is not consistent as you increase or decrease luminance. When you bump or decrease the luminance at a level, the R, G & B do not change exactly the same - those LEDs are not perfect. That means you will need to re-balance the RGB at the new level or you'll have some gamut change at that luminance level.
I normally like to calibrate with LD on, even though it's a pain, and that's because calibration characteristic will change when you change the IVC setting. You can get situations where an increase in R, G or B while trying to balance a particular grayscale level will jump the dE by more than 2 because you've crossed a local dimming threshold. That jump will not be exactly the same for R, G and B.
Also altering the white level will change the gamma across because White is the reference level that was used during the calibration. Now that reference has changed and it is not consistent across levels in between from black to white.
If you can go from IVC off to local dimming to IVC Advanced Low and not have measurable changes in gamma, gamut, grayscale and white balance then you have a magic TV
. And maybe you do. You're a lucky dude. Mine always exhibits these changes. But it does give an awesome picture, which we have in common