Cheetah Python Camera with USB3 Interface
–
User Manual
December 5, 2017
Page
50
of
78
Rev 1.0
4.7.5 Gain Controls
These parameters define analog and digital gain controls.
Figure 21: Gain Control.
AnalogGain
: Sets the Analog Gain. You can select from 1.0x (0 dB), 1.26x (2 dB), 1.87x
(5.4dB) and 3.17x (10dB) gain. Always apply analog gain before digital gain (5.7.1 Analog
Gain).
BlackLevelAuto
: When set to Continuous, this automatically adjusts the black level based
on measurements of the dark reference lines at the start of each frame (5.7.4 Black Level
Auto-calibration and Offset).
BlackLevel
: Controls the analog black level as an absolute physical value. This represents a
DC offset applied to the video signal.
DigitalGain
: This feature sets the Digital Gain from 1x to 15.9x in steps of 0.00097x.
DigitalGainRaw
: Controls the raw value of digital gain with inputs ranging from 1024 (1x)
to 16384 (15.9x). You can control the gain by ~0.00097x per step from 1.0x to 15.9x. To
determine the raw value, take the desired gain multiplier, subtract 1.0 then divide by
0.00097 and add 1024 or use the following formula:
1.
Raw Value =
[(Desired gain
–
1)/0.00097]+1024.
If the desired gain is in dB, use this formula:
2.
Raw Value = [[[anti-log10(Desired gain/20)]-
1]/0.00097]+1024.
For example, desired gain is 7.9x
Raw Value = (17.95 dB). [(7.9
–
1.0)/0.00097] +1024 = 8137 if the desired gain is 6dB, then
the code is 2050. Minimum setting is 1024 corresponding to 1x gain.
DigitalOffset
: This controls the digital offset for all taps. The offset is a digital count added
or subtracted from each pixel. The range is +/- 512 counts.
4.7.6 Auto Gain and Auto Exposure
You can set the camera to automatic exposure control (AEC) to keep the same image
brightness during changing light conditions. You can enable both AEC and automatic gain
control (AGC) independently or together. Auto gain and auto exposure controls let you
place minimum and maximum limits on auto gain/exposure.
