Datacolor User to User Support Group.

--- In colorvision_group@yahoogroups.com, "esimanor" <esimanor@...> 
wrote:
>
> --- In colorvision_group@yahoogroups.com, "Brian Smith" <zen1@> 
> wrote:
> > 
> > Contrast is definitely not gamma. 
> 
> Oh Yes! Gamma and Contrast are intricately linked. Your display (any 
> display) has got a native gamma that describes the way it is 
reacting 

They may be linked but they adjust the response curve in different 
ways. Contrast is a purely linear adjustment.

> 
> Now again, the confusion comes from the use of the wrong terminology 
> for the two tweaking knobs on your display: "brightness" 
> and "contrast". As said before, "brightness" relates to black level 
> (and as such it will have a direct influence on the contrast of the 
> picture). "Contrast" is brightning or darkening your white point 
> hence it is having an influence on the overall brightness of the 
> picture which shows the non sense in the choice of terminology...

Contrast controls the linear component of the slope of the response 
curve of your display device it is not specifically a white point 
control. However, if you specify the black point (the start point of 
the response curve) using the brightness control then adjusting the  
slope with the contrast control must adjust the whitepoint within the 
limits of the device but it is not specificaly a whitepoint control.

> 
>   
> > I don't believe that an observer is capable of making absolute 
> > luminance judgements.
> 
> Of course not, since luminance judgement is subjective and varies 
> from one viewer to the other and with ambiant light. Which is why I 
> don't quite see the use of being able to set your black and white 
> point luminance value in Candela unit in the Spyder Pro software 
> version. How do these candela setting relates to the viewer 
assesment 
> of display luminance?

> Yes but again, it is not the contrast that has to be adjusted for 
> comfort, it is the pedestal and the white point luminance
>

First you say '"Contrast" is brightning or darkening your white point' 
and then you say, 'Yes but again, it is not the contrast that has to 
be adjusted for comfort, it is the pedestal and the white point 
luminance'.

Don't you think you are contradicting yourself there?