Phytec FireWire-CAM-001, Manual

Page: 43 / 86

First Steps
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PHYTEC Messtechnik GmbH 2005 L-661d_1
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Advanced Settings
Call in AMCap:
Options
4
Video Capture Filter...
4
Advanced Settings
The Advanced Settings dialog allows access to a few special
parameters of the signal processor.
Here you can determine if and how the sensor’s defective pixels (so-
called „dead“ pixels) should be handled, which may be visible in the
picture in rare cases.
You can also determine in which format the input of the exposure time
should occur (any modifications require a restart of the driver).
One important setting option is the Frame Rate Reduction. The
camera’s refresh rate (image capture frequency) is usually 30 Hz.
With an artificial light source, interference can result at this rate.
This occurs because light from lamps powered by mains frequency is
not constant, rather it pulses with the mains frequency. This is
particularly noticeable with fluorsecent lamps. Since in Europe the
network frequency is not a whole multiple of the 30 Hz – capture
frequency, zebra stripes or flickering can occur in the image.
In this case activate the function Frame Rate Reduction:
ã
Frame Rate Reduction
This will reduce the refresh rate to around 25 Hz, which is a reduction
to approximately 83.3 % of the original value. Thus the interference
can be avoided.
Hint:
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The occurance of interference at 30 Hz is not a defect. Standard
TV cameras in Europe always operate at the lower frequency of
25 Hz to avoid this interference.
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The exposure time is (usually) independent of the picture
frequency. Therefore the settings do not influence each other.