Allied Vision Technologies AVT Marlin, Техническое руководство, Страница: 80 / 247

Description of the data path
MARLIN Technical Manual V2.4.0
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Manual gain
Marlin cameras are equipped with a gain setting, allowing the gain to be
manually adjusted on the fly by means of a simple command register write.
The following ranges can be used when manually setting the gain for the ana-
log video signal:
The increment length is ~0.0354 dB/step for CCD models and 1.25 dB/step
for CMOS.
Brightness (black level or offset)
It is possible to set the black level in the camera within the following ranges:
CCD models: 0...+16 gray values (@ 8 bit)
Increments are in 1/16 LSB (@ 8 bit)
CMOS model: 0 … +127 (@ 8 bit)
The formula for gain and offset setting is: Y’ = G x Y + Offset
Note
L
• Values can only be changed within the limits of gain
CSR.
• Changes in auto exposure register only have an effect
when auto gain is active.
• Auto exposure limits are 50..205. ( SmartView Ctrl1
tab : Target grey level )
• Auto gain is not possible with CMOS models due to
coarse gain settings.
Type Range Range in dB
Marlin CCD cameras 0 ... 680 0 … 24 dB
Marlin CMOS camera 1 … 14 0 … 16 dB
Table 33: Manual gain range of the various Marlin types
Note
L
• Setting the gain does not change the offset (black
value) for CCD models.
• A higher gain also produces greater image noise. This
reduces image quality. For this reason, try first to
increase the brightness, using the aperture of the cam-
era optics and/or longer shutter settings.