Basler Vision Technologies Sprint Series, Руководство пользователя

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Features
Basler sprint Mono Cameras 125
Generating and Saving User PRNU Shading Correction Values
The procedure below describes how to generate user PRNU shading correction values. When you
generate the values, they will automatically be stored in the camera’s user shading value file.
You should be aware that the camera uses one set of PRNU values when it is operating in single
line acquisition mode and a different set of values when it is operating in any one of the other line
acquisition modes (see Chapter 3 on
page 39 for more information about line acquisition modes).
This means that:
„
If you will always be operating the camera in single line acquisition mode, you should set the
camera for single line acquisition mode and then follow the steps below one time.
„
If you will never be operating the camera in single line acquisition mode, you should set the
camera for any one of the other acquisition modes and then follow the steps below one time.
„
If you will sometimes operate the camera in single line acquisition mode and other times
operate the camera in one of the other modes, you should first set the camera for single line
acquisition mode and follow the steps below. You should then, set the camera for any one of
the other acquisition modes and you should go through the steps a second time.
(The camera’s user shading values file has one area where it holds the PRNU values it uses for
single line mode and another area where it stores the values for all of the other modes.)
To generate a set of user PRNU values:
1. Place a uniform white or light colored target in the field of view of the camera. Adjust your light-
ing, optics, line rate, exposure mode, exposure time, gain and camera temperature as you
would for normal system operation.
2. Set the camera for the desired line acquisition mode.
3. Make sure the area of interest parameters are set so that the camera will use the full length of
the sensor (see Section 6.2 on page 118 ).
4. Perform several acquisitions and examine the pixel values returned from the camera. The pixel
values for the brightest pixels should be about 80 to 85% of maximum.
a. If the pixel values for the brightest pixels are at 80 to 85% of maximum, go on to step 3.
b. If the pixel values for the brightest pixels are not at 80 to 85% of maximum adjust your
lighting and/or lens aperture setting to achieve 80 to 85%.
5. Perform several acquisitions and examine the pixel values in each line. In each line, the values
for the darkest pixels must be at least 67% of the values for the lightest pixels in the line. (If the
values for the darkest pixels are less than 67% of the value for the lightest pixels, the camera
will not be able to fully correct for shading variations.)
a. If the values for the darkest pixels are at least 67% of the value for the lightest pixels, go on
to step 4.
b. If the values for the darkest pixels are less than 67% of the value for the lightest pixels, it
usually indicates extreme variations in lighting or poor quality optics. Make corrections as
required.