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1.4.4 Gain and Brightness
The Gain and Brightness adjustment functions are accomplished by
manipulation of the sensor’s digital output signal.
Please refer in Figure 1-4; when the
gain is set to 0, the full 10bit output
range of the camera’s CMOS
sensor will mapped directly to the
8bit output range of the camera. In
this situation, a gray value of 0 is
output from the camera when the
pixels in the sensor are exposed to
no light and a gray value of 255 is
output when the pixels are exposed
to very bright light. This condition is
defined as 0dB of system gain for
the camera.
As shown in the three graphs
below, increasing the gain setting to
a value greater than 0, maps a
smaller portion of the sensor’s 10bit
range to the camera 8bit output.
When a smaller portion of the
sensor range is mapped to the
camera output, the camera’s
sensitivity to a change in light level
is increased.
This feature can be useful when at
your brightest exposure, a gray
value of less than 255 is achieved.
For example, if a maximum gray
value of 127 is achieved with bright
light, you could increase the gain
setting so that the camera is
operating at 6dB; thus seeing an
increase in gray values to 254.
Figure 1-4: Gain Settings Mapping
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