Monitors and individual gun control
Monitors and individual gun control
- Subject: Monitors and individual gun control
- From: "Nick Milley" <email@hidden>
- Date: Tue, 12 Jun 2001 10:47:40 -0400
With regard to the questions about monitors and gun control, almost every
monitor today gives some form of analog color control via the OSD. Confusion
exists on whether control of individual RGB gains is superior to a Color
Temperature slider. Practically speaking, there is little difference between
the two methods as far as calibration of a monitor is concerned. Achievement
of a desired white point is possible with either method. With RGB gain
control, you adjust the individual settings until the desired white balance is
achieved. With Color Temp slider, you adjust the slider until the desired
white is achieved (the slider simultaneously adjusts the three guns for you).
Controlling RGB gains, however, gives you the additional benefit of
controlling white luminance through the settings - the greater the gains the
brighter the white. But beware, setting the gains too high can drive the
monitor into saturation and cause color shadows to appear.
It seems that 19" monitors tend to have color sliders while 22" monitors tend
to have individual gun controls. Just for the record, the Mitsubishi 920U and
the LaCie Electron19 are the same chassis - both have color sliders. The LaCie
is specially modified by Mitsubishi for LaCie and it comes with a viewing hood
and other features.
Calibration of these monitors is another issue. While it is important to set
the RGB gains correctly, it is more important that they be set in conjunction
with black level, dark gray bias, white level, and gamma. ADJUSTING ANY ONE OF
THESE INDEPENDENTLY CAUSES NOTICEABLE CHANGES TO THE OTHERS. For instance,
contrary to what has been written in this space before, adjusting brightness
drastically affects gamma (just turn up the brightness control on your monitor
and see if the apparent contrast ratio has changed), and it does affect white
luminance. So, changing monitor gains should require adjustment to brightness
and vice-versa.
Often overlooked in a calibration application is the control of dark gray bias
often called black level. These three controls mirror the function of RGB
gains only at a very dark luminance, usually 8 candela/m2 or so. Monitor
manufacturers have recently included these adjustments to improve the gray
balance at dark levels. Setting RGB gains without adjusting RGB bias amounts
to half a calibration.
Unfortunately, these controls can only be adjusted interactively by digital
control of the monitor. The only package I know of that includes the digital
interface and software to provide interactive digital calibration is the LaCie
BlueEye product.
Regards,
Nick Milley
Sequel Imaging