Basler Vision Technologies Sprint Series, Руководство пользователя

Страница: 61 / 236

Line Acquisition Modes
Basler sprint Mono Cameras 51
3.5 Time Delayed Line Summing
Acquisition Mode
When the time delayed line summing acquisition mode is active, each time a line acquisition is
triggered, the camera will expose both line A and line B. When line acquisition is complete (i.e.,
exposure is finished), the pixel values from line A and from line B will be handled in the following
manner:
„
The pixel values for line A will be read out of the sensor and will be stored in a buffer in the
camera.
„
The pixel values for line B will be read out of the sensor and they will be summed with the pixel
values for line A that were stored during the previous acquisition cycle. The values will be
summed in the following manner:
The value for pixel 1 in line A will be added to the value for pixel 1 in line B
The value for pixel 2 in line A will be added to the value for pixel 2 in line B
The value for pixel 3 in line A will be added to the value for pixel 3 in line B
And so on
„
The summed values are transmitted out of the camera as though they were from a single
captured line.
In essence, this process acquires each line on the object twice, sums the captured data, and reports
the result as if it was from a single acquisition.
Line summing can be useful if you want to decrease the noise level in the pixel values output from
the camera. Using line summing will result in an increase of approximately 3 dB in the signal-to-
noise ratio.
To better understand the concept of time delayed line summing, consider the example that is
illustrated in Figure 21 through Figure 24. The example looks at four contiguous "points" on an
object moving past the camera. Each point represents the area on the object that will be captured
by one line in the sensor when a line acquisition is performed. As you look at the figures, notice that
when each acquisition is performed, line A will capture one point on the object and line B will capture
a different point on the object.
Line A Delayed or Line B Delayed
When you use time delayed line summing, you have two choices: "time delayed line summing with
line A delayed" or "time delayed line summing with line B delayed." You should use "time delayed
line summing with line A delayed" if the image of the object you are capturing will pass line A first
(the object being imaged will pass line B fist). You should use "time delayed line summing with line
B delayed" if the image of the object you are capturing will pass line B first (the object being imaged
will pass line A fist).
In Figure 21 through Figure 24, the image of the object is passing line A first, and line A will be
delayed.