Having calibration problems

[Meeho]

I've been calibrating my displays for the last couple of days and they are driving me crazy. Calibration reports look great, but the LCD ends up with redish cast and the CRT a greenish one, compared to each other.

I'm using X-Rite i1 Display2 and BasicColor software, calibrating to D65, gamma 2.2.

Any ideas how to get the same results or is it impossible?

LCD: NEC 24wmgx3

CRT: Sony GDM-FW900

 

[Sailor_Moon]

I've been calibrating my displays for the last couple of days and they are driving me crazy. Calibration reports look great, but the LCD ends up with redish cast and the CRT a greenish one, compared to each other.

To get a visual consistent whitepoint in a dual screen setup consisting of screens emitting different spectra you have to think of some colorimetric limitations. The CIE 2 degree standard observer is not absolute accurate and there are considerable deviations between realworld observers. This leads to the effect that a colorimetric match can result in significant visual differences. You have to choose one screen as reference and calibrate with your desired whitepoint (6500K is not a must to work correct; 5800K is a good starting point - the colorimetric data is adapted to the reference white of the PCS during profilation anyway). The whitepoint destination for the other screen has to be adapted (which means experimenting with different targets) until there is a visual match for you.

Other problems arise through absolute errors in measurement. The organic gelatine filters of the i1 Display 2 are not very resistant to age and different probes are suffering from high deviations among each other. In addition they feature only two corrections für CRT and CCFL (72% NTSC) spectra – but that's OK for your current setup.

So the first thing you can do is to find a neutral whitepoint for your specific conditions and one screen. Then find a whitepoint for the other screen that matches the other visually.

Best regards

Denis

 

[Meeho]

How should I find a neutral whitepoint? When I first calibrated the Sony I thought it looked great. Now, with the NEC beside it, not so much

If achieving the same white point is so hard to do objectively with a calibrator, isn't it a problem, for example, in shared photo editing between distant computers?

 

[Sailor_Moon]

isn't it a problem, for example, in shared photo editing between distant computers?

No, think of the whitepoint as a transparent parameter (the reference white of the PCS is always D50 and the measurement data is adapted during profilation). The human visual system has the ability of chromatic adaptation. It is a common misbelief that you must calibrate with D65 ( I could heretically ask which D65? with respect to the effects mentioned in the posting above) to work for example in AdobeRGB or sRGB or to watch films as intended. The whitepoint must be neutral regarding your conditions. That's a bit difficult in the SOHO sector because the ambient conditions aren't fixed and/ or definied.

When I first calibrated the Sony I thought it looked great.

Then you could try to find a whitepoint target for the NEC that matches the Sony.

Best regards

Denis

 

[Meeho]

I see. Do you have a suggestion what parameters to change on the NEC to make it more greenish? Raising the white point makes it cooler, but Sony always has a more green cast in comparison. Green bias and then set calibration software to use native white point? Is it true that RGB offset/bias shouldn't be changed on LCD's?

 

[Meeho]

I have been trying to fix this, but no luck. Targeting higher or lower white point on the NEC doesn't help. I always have to lower red bias and/or gain in OSD to get somewhat similar black&white picture I use for comparison, but that totally messes with other colors and dE rise significantly. Could my i1 Display2 be faulty or is getting the same color and grayscale really this dificult on CRT and LCD?