Basler A640F, User Manual

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Basic Operation & Standard Features
3-18
BASLER A640
f
DRAFT
3.3 Gain and Brightness
The major components in the
A640
f
electronics
include: a CCD sensor, one VGC (Variable Gain
Control), and one ADC (Analog to Digital Converter).
The pixels in the CCD sensor output voltage signals
when they are exposed to light. These voltages are
amplified by the VGC and transferred to the ADC which
converts the voltages to digital output signals.
Two parameters, gain and offset are associated with
the VGC. As shown in Figure 3-10 and Figure 3-11,
increasing or decreasing the gain increases or
decreases the amplitude of the signal that is input to
the ADC. Increasing or decreasing the offset moves the
signal up or down the measurement scale but does not
change the signal amplitude.
For most applications, black should have a gray value
of 1 and white should have a gray value of 255 (in
modes that output 8 bits per pixel) or 4095 (in modes
that output 12 effective bits per pixel).
L
Because increasing gain increases both signal and noise, the signal to noise ratio
does not change significantly when gain is increased.
Figure 3-10: Gain
Figure 3-11: Offset