Image Processing Reference
In-Depth Information
1. There is no software solution to apply. Do not try to compensate by altering your
video content.
2. It is not your video that is at fault but your display monitor. Switch from CRT to
LCD flat screen.
3. Recalibrate the convergence settings on your CRT.
Hanging Dots
Areas of red and blue appear to shift even though the pixels are lined up precisely. This is
an artifact of the human eye that appears to place blue and red objects at different
distances on the Z-axis. It is not actually a displaced portion of the image but a conse-
quence of the human eye's having a different sensitivity to blue and red (Figure 36-2).
What is really in the display.
What the eye thinks it sees.
Figure 36-2 Hanging dots.
1. This is not actually a fault but an illusory artifact. You cannot fix it by modifying
your video content.
2. It is a property of the display. Replacing your CRT with an LCD monitor may
Comet Trails and Dark Pixels
Older video cameras with plumbicon tubes used to suffer from a persistence effect where
a bright point source would desensitize the phosphor in the camera tube for a short period
of time. This would cause the phosphor to act as if it were still lit for a few frames after the
light source was removed, and the camera output would continue to show a ghost image.
A related effect would be if the middle of a large bright area saturated the tube and
momentarily burned it out so that the middle of a light source would appear dark.
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