[argyllcms] Re: Contrast vs Brightness on my LCD monitor and related questions
- From: Peter Karp <pmailing@xxxxxxxxxxxxxxxx>
- To: Leonard Evens <argyllcms@xxxxxxxxxxxxx>
- Date: Sat, 6 Dec 2008 23:23:44 +0100
Hi Leonard,
> I still feel I am having difficulties because I don't understand hwo
> to use Brightness and Contrast in the monitor controls.
For a TFT it's mostly easy. Reet the contrast setting to the default
value and never touch it again. This setting is totally nonsense and I
still wonder what the engineers/companies are thinking when they use
it on a flat screen display. Contrast setting on a CRT was a whole
different story (setting the gain).
Some better displays don't show you a contrast setting at all (Eizo,
Quato - when digitally connected). That's the best way. Others (for
example some NEC models) offer a contrast setting, but can be reset to
the default values pretty easy. Some displays offer a contrast setting
and it's not possible or unclear how to reset the complete OSD
settings or a specific one alone. This is the worst case. If possible
don't buy such a display.
> Also, with the RGB monitor controls set at the default 50/100, I am
> getting lower color temperatures than I would prefer. I will
> experiment some more with the controls and also try setting the
> color temperature.
I don't know your specific model, but in general it's a very good idea
to start from the default/factory values.
1) Don't touch contrast setting at all. (They use the monitor LUTs to
mimic a CRT behavior which does not make sense and will lead to
banding) -- so if available reset to the factory value.
2) Test if the brightness setting only influences the backlight --
which it should. For this matter use some gray ramps and/or gradients
(non colormanaged is the best for this purpose). You should not loose
any levels, when altering the brightness. If it does, take care or
better buy a better display which does not connect the monitor LUT to
the brightness control.
3) If RGB default values leave headroom then test if increasing the
RGB values will lead to banding in R, G, B, Gray ramps. If it does not
you can use the complete range, if it does you have to reset the RGB
values to the default value and wire those default values as the
maximum _usable_ values to your brain ;-)
4) Use the brightness control to set desired luminance (or slightly
higher, because you will loose some luminance when you use the RGB
settings to reach the target whitepoint).
5) Then you can alter the color temperature (white point) with _two_
of the RGB controls. Leave one of them -- depending on the choosen
whitepoint -- at the maximum _usable_ setting. As a hint you can
remember that lowering the green channel will also raise the measured
value for the other two channels (on most displays).
6) Recheck the luminance if needed/wanted. Important: the visual
appearance of the luminance (depending on the ambient light!) is much
more important then to reach a specific measured value.
Alternativ route when you want to buy a new display: look for a
display which can be hardware-calibrated. For example used NEC 2180UX
go pretty cheap and can be calibrated under OS X and Windows with some
solutions.
Hope this helps a bit.
Regards
PEter
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