knöll systems - advanced home products
http://www.knollsystems.com/dither.htm
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1/21/2005 1:07 PM
Line dithering on a lower cost projector is a way to significantly improve image quality at a
fraction of the cost of a line doubler and projector that can display line doubled images.
Line dithering was added to the HT300 because low resolution, high contrast images (eg.
hockey games on cable TV) are frequently viewed with the line doubler disabled because
line doubled image sharpness can be seriously reduced by low resolution, high contrast
image sources. While viewing a Knöll projector with line dithering, the dithering is present
on portions of the image that are still (blanking lines are absent), then as soon as motion
starts on that portion of the image, the black lines reappear on the moving portion only,
then disappear when the motion stops.
Fig. 2
Image with and without line dithering
The right side of this image shows black lines between scan lines without the use of line
dithering. The left side of the image show video scan lines with the use of Knöll series I
line dithering. With line dithering the viewer can sit very close to the screen and get a more
accurate cinema experience.
Line dithering also has the effect of making a projector last longer with a brighter image.
This is possible because the phosphor on the CRT's (cathode ray tube) is more evenly
heated as there are much fewer hot (scan line), cold (black line), hot (scan line areas). And
because more of the CRT is lit, the image is brighter.
Without line dithering the black lines in between the scan lines is always present. The
Knöll
HT3 with Series I line dithering works about 45-55% of the time
removing black
