Re: LCD Black Level adjustment slider? [Controls on CRT and TFT]
Re: LCD Black Level adjustment slider? [Controls on CRT and TFT]
- Subject: Re: LCD Black Level adjustment slider? [Controls on CRT and TFT]
- From: Peter Karp <email@hidden>
- Date: Wed, 3 Jan 2007 11:04:12 +0100
Hi Russell,
it seems so far no one has answered your question.
> I'm helping someone calibrate their LaCie 320 LCD monitor and am faced
> with a new menu setting and the Brightness/Contrast settings on an LCD do
> not behave the same way as they do on a CRT.
That's true. The naming "brightness" and "contrast" is (mostly) used
different on CRT's and TFT's.
> What does the Black Level adjustment **SLIDER** do on this monitor?
I don't have experience with this particular model, but can give
general advice which might help you here.
> It's a third adjustment setting offered on the same
> "Brightness/Contrast Controls" menu which includes Brightness
> (default is 100) Contrast (default is 50) and Black Level (default
> is 50).
Just one question. Are those settings available both when the display
is connected analog via VGA or digitally via DVI? Sometimes contrast
or black level setting are only available in analog mode. In digital
mode they never make sense! Normally you'll want to leave them at the
default values (whatever this is for a specific display). This is true
for DVI connected displays always and I never came across a TFT where
it would have been different for VGA mode, but in theory there could
be cases where slight adjustments could be needed because of different
analog signals from different graphics cards or with different cable
lengths. Although I strongly suggest to find out the default values
and use them! I always advice to connect a flat panel display via DVI
of course.
> I've never seen a "Black Level" slider on a monitor adjustment menu and
> have used the Brightness setting in the past to achieve a proper black point
> on CRTs. Is this "Black Level" setting now common on LCD monitors?
I know only one LCD monitor (out of production for quite some time)
which offered a "black level" setting in analog mode, but few might
have such a "slider".
> For the 1st attempt at calibrating I adjusted only the Brightness setting to
> lower the white point from close to 200cd/m² to about 105cd/m². I
> understand the LCD's brightness adjustment affects the `back light´ intensity
> and does what's normally achieved via the Contrast setting on a CRT.
Yes, that's correct. The backlight brighness of a TFT and the contrast
setting of a CRT will affect the brightness of the monitor.
> I left the Contrast and Black Level settings at their default values
> of '50'.
That's a good practice too.
> The result looks good but I wonder if there is a rcommended methodology in
> approaching these 3 settings properly. Does one just set the Brightness and
> then let the profile do all the work?
Yes, that's the best.
Here's a table what options you might find for different display types
and how to use them for calibration
TFT CRT
Backlight Brightness a [1] -
Gamma adjustment s -
Brightness s! a
Contrast s! a
RGB setting s a
RGB Bias - s
Brightness = Bias = Black Level
-> sets the offset of the analog video signal
Contrast = Gain
-> sets the gain of the analog video signal
RGB setting = RGB gain = RGB contrast ~ Color temperature
Legend
------
a = all -> should be used for calibration
s = some -> should be used if available
s! = some -> but should be set to default values, otherwise clipping
is _very_ likely to happen
[1] Backlight Brightness does not have a significant influence on the
profile quality. You can and should set the backlight brightness to
match your viewing conditions. You can do this even without
recalibrating and the introduced error is negligible (Delta E will
increase about 0.5 when you're using a Quato Intelli Proof display).
Although all those tips apply to a manual aided "software
calibration", while the best calibration quality will be achieved when
using a high-end hardware calibrated display. I'm biased and will
favour our Quato Intelli Proof 213 displays, but NEC and Eizo or LaCie
also have hardware calibrated displays.
With kind regards
Peter Karp
Quatographic Technology GmbH -- www.quato.de
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