Balancing The Gain On Odd And Even Pixels; Refresher On Db - Basler L100k User Manual

3.5.1 Balancing the Gain on Odd and Even Pixels

As described on the previous page, gain alignment between the channels is important to maintain
uniform output data with minimal gray value differences between odd and even pixels.
In some applications, multiple cameras are used, for example, when several line scan cameras
are used next to each other to form one large image. Another example is that a camera in an
existing application is replaced. In these cases, it is also necessary to balance the gain between
cameras.
To meet the goals of balanced channels and comparable camera output, each Basler camera is
calibrated before it leaves the factory. This calibration procedure has the following effects:
• The factory gain settings for the odd and even channels are aligned so that they equally
amplify the signal and a uniform output is achieved on both channels. In addition, they are
set to a low gain value to obtain an optimal operating point (low noise, good odd/even chan-
nel match)
• There are reference gain values which can be used to calculate higher or lower odd and
even gain settings so that the channels remain balanced.
• All cameras have default gain settings and reference gain values which match the output of a
factory master camera of the same type. This output is referred to as 0 dB. So if a camera's
gain is set to 2 dB, this means 2 dB more than the gain of the master camera.
The reference gain values can be used to calculate higher or lower gain settings that will keep the
odd and even channels in balance and comparable to other cameras of the same type.
If you use the Gain setting in the Camera Configuration Tool Plus (see Section 4.1) to set the gain
on your camera, an "auto-balance" feature will automatically use the stored reference values to
keep the channels in balance. If you want to set the camera so that the channels are not balanced,
you can use the Gain Balance setting to change the gain on the even pixels only.
If you use binary commands (see Section 4.2) to set the gain, you can use the reference values
to calculate gain settings that will keep the channels in balance. To do this, you must select a
desired gain in dB to achieve and then use the reference values along with the formulas shown
on pages 3-12 through 3-15 to calculate the required settings for the odd pixel gain and for the
even pixel gain. You can then enter the calculated settings into the camera using the appropriate
commands.

3.5.1.1 Refresher on dB

A value given in dB is basically a factor. The general
formula to calculate a gain factor in dB is as follows:
dB =
Or, in other words, an increase by 6 dB corresponds to a
factor of 2. A decrease by 6 dB corresponds to a factor of
0.5.
BASLER L100
k Series
DRAFT
⎛
camera output
×
20 log ---------------------------------------------------------------- -
⎝
reference camera output
Gray value [DN]
⎞
⎠
Operation and Features
+ 6 dB
x 2
- 6 dB
x 0.5
light intensity
3-11