Instruction manual

UltraLink 2 DVI Installation and Operation Manual 29
It is also possible to create a keystroke sequence as described above in a text document on the connecting
computer, copy it to the clipboard, and send that combination to the UL2-DVI using the Paste Clipboard button.
In order to use this feature, the Share clipboard with server option must be enabled in the Inputs tab of the
VNC Viewer Connection Options screen.
Use the Close button to exit the Keyboard Control screen and return to the VNC Viewer window.
Video Settings
The Video Settings selection displays a screen for optimizing the digital video signal. The resolution of the
incoming video is also displayed. The main function of this screen is to control the effect of image dithering on
video quality.
Video cards that support image dithering enhance image quality by gradually changing the colors of
neighboring pixels across the image. By doing this, the video card adds more shading to the image rather than
blocky areas where there is an abrupt change from one color to another. The drawback for UL2-DVI is that
since the pixels change so much over an area, increased network bandwidth is required to transfer a heavily
dithered image. Dithering can even cause the unit to see changes in a static image. The UL2-DVI attempts to
economize on network bandwidth and speed image updating by sending just the changes to the image across
the network. When an image is dithered, the unit may see changes where there is merely color gradation. This
can cause the unit to refresh practically the entire screen each cycle rather than just actual changes to the
image. This will slow video updating and can make mouse movements appear jerky. The Video Settings menu
item provides a way to minimize the effect of image dithering on video quality.
Figure 41. Video Settings screen
The Ignore Dithering checkbox is used to cause the UL2-DVI to ignore minor changes to the image from frame
to frame. By default, it is not checked, so that the unit transmits the image with the best color accuracy and
least usage of network bandwidth for video from non-dithered sources. Selecting this option for dithered video
sources such as Apple Mac computers, or for noisy video sources such as cameras or VGA to DVI converters,
tells the UL2-DVI to ignore video changes below a certain level.
The Threshold field is used to indicate how much change should be considered significant. Drag the slider with
the mouse to make large changes in threshold value, or use the arrow buttons on either end of the slider for
small increments or decrements. Clicking the Auto button causes the UL2-DVI to determine the best value
automatically.
The Display Activity field shows how much change is being seen in the image. It can be used as a measure of
how much noise is present in the image transmission. A high display activity value on a static image indicates
a lot of noise, causing mouse motion to be jerky.
For best results, check Display Activity when a static image is displayed. If the Display Activity number is high,
the Threshold value is too low. Increase the Threshold value until the Display Activity is near zero. Then view
the screen with a video playing, to be sure that actual changes are not being missed. Modify the Threshold
until it is at an appropriate value.