[argyllcms] Re: White point or black point adjustment not working

Hi,

George Willegers wrote:


A line showing R+ G+ B-- changes into something like R-- G- B+
And this keeps going on, even if I do change the monitor settings, 


Can anyone explain what is happening, and better how it can be stopped?
Below is some output of dispcal.



Adjust R,G & B offsets to get target x,y. Press space when done.
  Target Br 0.34, x 0.3025, y 0.3512
/ Current Br 0.47, x 0.2950, y 0.3346  DE  8.1  R+  G+  B--
I don't know what settings are available on your particular monitor but with many LCDs there's not a lot you can do at the black end of the scale. If you only have one set of RGB controls, use them to tune the white point rather than the black point. If you have RGB offset controls as well, then it's worth playing with the black-point.
The fluctuation you're seeing is just due to your instrument's repeatability not being perfect, and isn't the huge problem it might appear at first sight.
When tuning the white point, you should find that dispcal displays a current colour temperature, a dE value and suggested adjustments. Your goal here is to minimise the dE while achieving the colour temperature you want. If you're lucky you'll be able to get the dE low enough that the RGB "suggestions" will read R= G= B=. With less-than-perfect repeatability you might not manage that, but just get the dE as low as you can. 

Hope this is some help

All the best,
--
Alastair M. Robinson

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