Chapter 5: Operation
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Ignore Dithering
The ‘Ignore Dithering’ option increases performance and reduces network
traffic when the host computer is an Apple Mac or another computer that
has dithered video output. It also improves performance if the video source is
noisy (e.g. from a camera or a VGA-to-DVI converter).
5.8.8 Video settings
This option provides a range of options related to the video configuration.
Dithering is a technique used by some graphics cards to improve perceived image quality by continuously slightly varying the color
of each pixel. This gives the illusion of more shades of color than the display can really reproduce, and smooths the appearance of
gradually shaded areas in images. Unfortunately, dithering is an issue for KVM extenders such as Wizard DXS - Digital because it
makes the image appear to be changing all the time even when it is static. This means that a great deal of unnecessary network
data is sent to the VNC viewer, reducing the video frame rate and making mouse response appear slow.
The
Ignore Dithering
option works by ignoring small variations in the video from frame to frame. It is disabled by default to give
full color accuracy and the best possible frame rate from non-dithered video sources.
The
Threshold
setting adjusts the level of dithering noise that is ignored. The ‘Auto’ button attempts to choose a suitable value
automatically, but the level can also be adjusted manually using the slider or arrow buttons. The best value is of course a
compromise between capturing all the ‘real’ screen changes whilst ignoring the (almost invisible) dithering noise. A good way to
choose the value is to watch the
Display Activity
indicator for a static screen. If the Threshold is too low, the Display Activity will
be a high percentage while nothing is really changing. If the Threshold is too high, the Display Activity will be very low (or zero)
but some real changes in the screen may be missed.
