The matrix (rXYZ/gXYZ/bXYZ) is not just the primaries. Is there any reason that the CM engine choose a white point that is neither the calibration intended white point nor the actual white point measured after the calibration? In the correlated temperature session of verification, almost all white points are around D65 (+50K), so it is unlikely that 6734K is an average. when I tried to profile it using a matrix+curves option, the profiled white point is always far from the intended value. P.S, I got the intended D65 in the profile and mostly consistent matrices by choosing XYZ-LUT type profiling.
Does this have anything to do with calibration settings? I always do some of it by adjusting the display itself and leave the rest to video card LUT. So here is the thing, strange white point coming from nowhere, strange matrices coming from no where yet contradicting each other. But I vaguely remembered once these values seem to be from 'R/G/B column matrix' !!! This confused me quite much since they provide such ambiguity in define the color space and what's worse, neither of these two is the correct one! The correct coordinates from 'chromacity' can only be verified by measuring and do not participate at all in color space transormation !
#Displaycal white point verification#
The next thing i found is the nominal values (XYZ) used in verification of such a profile, are actually the first ones from 'colorants (PCS-relative)' if relative is selected or ones chad-transformed to 6734K if absolute is selected. The 'chromacity' surprisingly records almost the exact measured xy values of the display, but since they don't have Y values for each primitive, it does not decide the white point.
The values from column matrix are connected by a chad from 6734K to D50, which I have verified. I know the PCS-relative always refer to D50 equivalents transformed via a Bradford chad, but the weired thing is values from these three categories are not consistent even with chad.
'Colorants (PCS-relative)', 'R\G\B column matrix (both illuminant relative and PCS-relative)' and 'chromacity (illuminant-relative)'. Is there any reason that the CM engine choose a white point that is neither the calibration intended white point nor the actual white point measured after the calibration?Īlso I notice there are two many XYZ trimulus of display RGB under different tags in the profile. However, when I tried to profile it using a matrix+curves option, the profiled white point is always far from the intended value. I have always calibrated my display to D65, and verified that the white point is indeed quite close to D65 from Calman of verification session of dispcalGUI.
0 kommentar(er)
