[argyllcms] Re: Choosing a monitor
- From: Peter Karp <qmailing@xxxxxxxxxxxxxxxx>
- To: Frédéric Mantegazza <argyllcms@xxxxxxxxxxxxx>
- Date: Thu, 10 Jan 2008 13:48:51 +0100
> Le 10/1/2008, "Peter Karp" <qmailing@xxxxxxxxxxxxxxxx> a écrit:
> The best way is to choose a monitor with an specific backlight control,
> in addition to the brightness/contrast ones, so we are sure this is not
> a LUT manipulation!
Yes that's right principally, but some low-end displays offer a
backlight control _and_ still alter the LUT (clipping might occur!) at
some point when using the "Brightness" control. Choosing a quality
monitor you'll not see such a stupid behavior. You can use an
artifical gray ramp on the desktop (non-colormanaged) to detect such a
problem.
Roger is right that a TFT can't have a contrast setting, but still you
find it in many displays. Then the contrast setting of a CRT is more
or less mimiced by LUT changes. This will not make any sense, but you
find it in many (cheap) displays.
Not everybody might be aware of the parameters in a CRT vs. an LCD. So
here a short summarize:
CRT: Brightness parameter -- also called Bias, Blacklevel in some
OSD's (On Screen Display) will have main effect on the shadows.
Technically it adjusts the bias of the _analog_ video signal.
Contrast parameter -- sometimes also labeled "gain". This setting
influences the gain of the analog video signal and will mainly have
influence on the luminance (perceived "brightness") of the display.
LCD (I assume digital connection): Brightness parameter -- dims the
backlight up/down. Influences shadows, midtones and lights! Although
the name in the OSD is the same as for CRTs the meaning of
"brightness" is totally different. Therefore I normally use the terms
"backlight brightness" vs. "blacklevel brightness" to differentiate
between both.
Contrast parameter -- is (or should be!) absent in an LCD OSD. If it's
there don't touch it or reset it to the default values which are
normally the only ones which makes sense.
BTW, the Fogra is working on a white paper explaining softproof and
monitor calibration. This will also cover this subject. It's planned
to be released end of february. You'll find it at www.fogra.org then.
Best regards
Peter
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