Basler L800k, Руководство пользователя

Страница: 65 / 168

Operation and Features
BASLER L800
k
3-25
Draft
4. The camera must capture at least 16 lines to create a set of DSNU shading correction
values. If your camera is set to control exposure with an ExSync signal, you must generate at
least 16 ExSync signal cycles after you signal the camera to begin generating the values. If
you are running the camera in a Free-run exposure mode, you must wait long enough for the
camera to capture at least 16 lines.
a) When the camera is capturing the lines it needs to create the DSNU shading values, the
line valid and data valid signals will go high and low as you would normally expect.
However, the data in these lines is not useful to you and should be ignored.
5. Once 16 lines have been captured, the camera calculates the DSNU shading correction
values:
a) The camera uses the data from the 16 captured lines to calculate an average gray value
for each pixel in the line.
b) The camera finds the pixel with the highest average gray value in the line.
c) For each of the other pixels in the line, the camera determines the offset that would be
needed to make the pixel’s average value equal to the average value for the highest
pixel.
d) The camera creates a set of DSNU shading values that contains the calculated offsets.
The set of DSNU values is placed in the camera’s volatile memory. This set of values
overwrites any DSNU shading values that are already in the memory. The current set of
DSNU values in the volatile memory is used whenever DSNU is enabled.
Enabling DSNU Shading Correction
Once you have a set of DSNU shading values in place, you can enable and use DSNU shading
correction. With the DSNU correction feature enabled, the camera will use the set of DSNU
shading values to apply the appropriate offset to each pixel to correct for DSNU.
You can enable DSNU shading correction with the Camera Configuration Tool Plus (CCT+) or by
using binary read/write commands from within your own application to set the camera’s control
and status registers (CSRs).
L
If you started the generation of the shading values using the CCT+ and you are us-
ing an ExSync signal to trigger line capture and you are operating the camera at a
line period greater than approximately 300 ms, you should be aware of a potential
problem. Under these conditions, the CCT+ may time out while it is waiting for the
camera to capture 16 lines and you may see a “Camera is not responding ...” error
message. This error is not fatal to the shading value creation process. If you close
the error message window, wait several seconds and then click the Refresh button
on the CCT+, the shading values will be properly created.
If you started the generation of the shading values using binary commands and you
are using an ExSync signal to trigger line capture and you are operating the camera
at very low line rates, you should be aware of a restriction. The camera will not ac-
knowledge or respond to binary commands while it is performing the 16 line cap-
tures needed to create a set of shading values. Once you have issued the binary
command to start generating shading values, you should wait until the generation
process is complete before you issue any further binary commands. The time
needed to complete the generation process will be equal to 16 times the line period.