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This is a technical question. In the uniformity report, how are the deviations computed?
For example, in the following image, the deviations for the 100% brightness, are given by ” 1 – val / ref”, where ref is the luminance of the central patch and val is the luminance of the patch I am analysing.
However, for 75% of brightness or less, this formula does not apply anymore. So how to compute the deviations for these cases?
It calculates contrast. At 25% , 50% , 75%, 100%. Compareing to center screen. I wonder if compares 50% to 50% etc or computes it from the 100%.
T
You’ll have to look in JS code for a bug.
Also do not use dE evaluation criteria, switch to dC, -10/-15% on corner/sides is unavoidable without UC. You shoould worry about color tints, if present,
Uniformity compensation UC, Blackpoint compensation BPC, Hardware internal calibration in a monitor HW cal etc…
It calculates contrast. At 25% , 50% , 75%, 100%. Compareing to center screen. I wonder if compares 50% to 50% etc or computes it from the 100%.
T
The ISO standard indeeds mentions contrast ratio.
https://cdn.standards.iteh.ai/samples/57311/19256ef439e54e00a1724d18f3640e47/ISO-12646-2015.pdf
However, the report in the image I attached does not present the resultas as ratios. It presents values in cd/m2, so these are absolute values, not ratios.
Lets consider the central square. Luminance at 100% is 124.5 cd/m2, while luminance at 75% is 64.62 cd/m2.
Lets now consider the top-left square. Luminance at 100% is 105.23 cd/m2 (-15.48%), while luminance at 75% is 53.8 cd/m2 (-8.69%).
So if I do (1 – 105.23 / 124.5) * 100 = 15.4779% ~ 15.45%
However, if I do (1 – 53.8 / 64.62) * 100 = 16.7440%, which is clearly not 8.69%.
What I want to know is how DisplayCal computes 8.69% instead of 15.45%.
