Basler A102f, User Manual

Page: 39 / 170

Basic Operation & Standard Features
BASLER A102
f
3-17
DRAFT
3.5.1 Setting Gain
When the gain is set to default, the
sensor’s linear output range
directly matches the input voltage
range of the ADC. Thus, with the
default gain of 0 dB, a gray value
of 1 is produced when the pixels
are exposed to no light and a gray
value of 255 (in modes that output
8 bits per pixel) or 4095 (in modes
that output 12 effective bits per
pixel) is produced when the pixels
are exposed to bright light.
0 dB of gain is achieved when gain
is programmed to a decimal value
of 192. Increasing the gain setting
to more than 192 maps a smaller
portion of the sensor’s linear
output range to the ADC’s input.
Increasing the gain is useful when
at your brightest exposure, a gray
value lower than 255 (in modes
that output 8 bits per pixel) or 4095 (in modes that output 12 effective bits per pixel) is reached.
For example, if you found that at your brightest exposure your gray values were no higher than
127 (8-bit mode), you could increase the gain to 6 dB (amplification factor of 2) and thus reach
gray values of 254 (see Figure 3-9).
Gain is adjustable and can be programmed on a decimal scale that ranges from 192 to 1023
(0x0C0 to 0x3FF). The camera’s gain is determined by the setting in the Value field of the Gain
control register (see page
4-23 ).
If you know the decimal number (DN) setting for the gain on your camera, the equivalent decibel
value can be calculated using one of the following equations:
L
When the camera is set for Mono 16 output, only settings from 192 to 511 are valid.
Settings above 511 should not be used with the camera set for Mono 16 output. In all
other output modes, the entire 192 to 1023 range of gain settings is valid.
In normal operation, a gain setting lower than 192 should not be used. When the gain
setting is lower than 192, the sensor output signal that is mapped to the input of the
ADC will not be linear.
Figure 3-9: Gain Settings in dB
When DN setting = 192 to 511
dB 20 x log
658 DN +
658 DN
–
-------------------------
⎝ ⎠
⎛ ⎞
- 5.221
=
10
When DN setting = 512 to 1023 dB 0.0354 DN
×
5.221 –
=