Hi Dave, 

I asked a friend who I know is pedantic about these things:

There are a bunch of things that could be causing problems.

Using DVI-D (digital) connections for both displays will probably help, at
least you will be using the same image processing circuitry in both displays
and same behaviour from the display driver then.

Go through all of the display menus on both panels and make sure they match
(particularly colour/white point temperature).  Having the same settings on
both doesn't guarantee that they'll match (see below), but you should start
there and then, from that point, try tweaking one of them towards the other.
Often the displays don't offer much control via the on-screen displays when
using DVI-D connections, so you may have to use options in the display
drivers instead or in combination.

The backlight in the displays becomes dimmer with age (and takes longer to
reach peak brightness).  This is affected by the number of hours the
backlight has been running rather than the actual age of the display.  A
dimmer backlight affects both the brightness (obviously) and will also
affect colour to some degree.

If you need accurate colour rendition, the you need to use a colourimeter to
calibrate the monitors.  If the displays are quite different, this will not
get them looking the same, because the colourimeter can't deal with
differents in brightness or dynamic range, but at least the colours will be
accurate.  If there's already a colourimeter in the company, this might be
the best place to start first... otherwise the cost of a colourimeter starts
at around $250.

Manufacturers make changes to the monitor builds over time, so it's possible
that the same model monitor may be built with a completely different image
processors, firmware, LCD panel, and backlight.  If the serial numbers are
very close, this is unlikely, and for higher end displays the parts used in
the build tends to be much more consistent.  Having said that, I have two
24" Dell displays (hardly print-press quality, but they are higher end
displays) that were bought about 2 months apart that have different panels
and quite different brightness and colour rendition.


> >>> Dave Reynolds <dave.reynolds at tait.co.nz> 5/09/2008 1:51 p.m. >>>
> Hi
> Not exactly Frame related, but I'm after some advice about LCD 
> monitors.  After being the only tech writer in our team with a single 
> monitor, I finally got given another monitor a couple of weeks ago.  
> Hurray!!  It's been a long wait.  So now I have matching Viewsonic VA912 
> 19" monitors.  The second one is not new, but reassigned to me from 
> someone else.  Judging from the numbers, it is about the same age as my 
> first monitor.
> Apparently my PC has an on-board video card, so they connected the 
> second monitor via an adaptor card (budget constraints!).  This meant I 
> had the first monitor on an analog feed, and the second monitor on a 
> digital feed. 
> The display on the second monitor is quite different from the first 
> monitor in terms of colour, brightness and contrast.  I have tried to 
> adjust the second monitor to match the display of the first monitor, but 
> I've been unsuccessful.  I've tried the adjustments on the monitor and 
> in the driver, but the display on the second monitor is still inferior 
> to that on the first monitor.  After complaining to our IST people, they 
> fitted a new video card that they happened to have in stock (still 
> budget constraints), but I notice that the first monitor is still on 
> analog, and the second is still on digital, and I still can't get the 
> displays to match.
> For many applications this is only a nuisance.  However, for editing 
> photographs it is a major problem.  I take quite a few photos for my 
> manuals and it is important that the edited versions of the photos I 
> take are consistent for colour, brightness and contrast.  This means 
> that I cannot currently use the second monitor for editing photos, as 
> the same photo looks so different on each monitor.
> Is there a way to get the second monitor to match the first one, or am I 
> fighting a losing battle trying to get the digital input display to 
> match the analog input display?
> Any help appreciated.
> Thanks
> Dave

Matthew Gregan                     |/
                                  /|                    kinetik at flim.org
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