Originally Posted by mttpalmer
I thought I read somewhere that the luminance controls were fixed via a firmware update? Regardless, does a luminance adjustment of -3 equate to a -3 for each of R, G, and B? If so, then I can just go in and fix without recalibrating.
There differences over firmware around the world (even with same version), there variations over manufactured revision electronics, to some areas it has less issues, to other areas more issues.
About reducing equally steps of all controls, it will require re-adjustments, because Green has more luminance from Red or Blue.
When you are looking the RGB Balance Chart of a calibration software and you see all (R/G/B) Channels Bars to be at exact 100% = 0 dE; doesn't mean that you have used equal percentage of luminance per each color channel.
The calibration software it's doing the normalizing internally according to the selected colorspace target options to give you better presentation for easier calibration.
D65 White Point for REC.709 (BD Movies) Color Space is using Red 21.27%, Green 71.52%, Blue 7.22% which gives 6504K.
REC.601 (PAL...EU DVD) D65: Red 22.20%, Green 70.67%, Blue 7.13% which gives 6504K.
REC.601 (NTSC... US DVD) D65: Red 21.24%, Green 70.11%, Blue 8.66% which gives 6504K.
REC.2020 (UltraHD Movies) D65: Red 26.27%, Green 67.80%, Blue 5.93% which gives 6504K.
All these colorspaces are using D65 as reference white point.
We use D65 (which has been created with specific mixture of RGB) which has 6504K because this is the white point the movies has been mastered (BD/UHD).
Each colorspace (REC.709 for BD / REC.2020 for UHD) while they have the same xy cordinates to create the D65, it's using different mixture of RGB colors channels, while all they report 6504K.
You can have 6504K temperature with different RGB channels mixture.
When you are using a meter/calibration software but you check only the Color Temperature Chart for the Grayscale, while the Color Temperature Graph can be perfect, the same time the RGB Balance Chart can be off.
This is happening because just a number 6504K is not the same as when we say D65 for a specific colorspace.
So when you are adjusting RGB balance controls, the Green channel adjustment is affecting more the luminance compared to the other 2 color channels, also when you reduce equally a specific point RGB sliders (-5 to all RGB sliders of 40% control for example), it can undo your RGB balance