Basler raL2048-48gm User Manual download pdf (Page 192)

Standard Features AW00118302000

182 Basler racer GigE

Creating a "Usershading" File for Gain Shading Correction

To create a "usershading" file for gain shading correction, perform the following steps:

1. Adjust the lighting, optics, line rate, exposure time control mode, exposure time, gain, and

camera temperature as you would for normal operation.

2. Place a uniform white target in the field of view of the camera.

3. Set the camera’s X Offset and Width parameters so that the entire width of the sensor lines will

be used during frame acquisition.

4. Perform several line acquisitions and examine the pixel values returned from the camera. The

pixel values for the brightest pixels in each line should be about 90 to 95 % of maximum (i.e., if

the camera is set for 8 bit output, the pixels should be from 90 to 95 % of 255).

a. If the values for the brightest pixels are at 90 to 95 % of maximum, go on to step 5.

b. If the values for the brightest pixels are not at 90 to 95 % of the maximum, adjust your

lighting and/or lens aperture to achieve 90 to 95 %.

5. Perform several line acquisitions and examine the pixel values returned from the camera. In

each line, the values for the darkest pixels must be greater than 1/4 of the values for the

brightest pixels. (If the values for the darkest pixels are less than 1/4 of the values for the

brightest, the camera will not be able to fully correct for shading variations.)

a. If the values for the darkest pixels are greater than 1/4 of the values for the brightest, go on

to step 6.

b. If the values for the darkest pixels are less than 1/4 of the values for the brightest pixels, it

usually indicates extreme variations in lighting or poor quality optics. Make corrections as

required.

6. Select Gain Shading in the Basler pylon Viewer or via the Basler pylon API.

7. Select "usershading" file in the Basler pylon Viewer or via the Basler pylon API.

8. Go to the Create enumeration in the Basler pylon Viewer and select Once or send a create

command via the Basler pylon API.

9. Perform at least 128 line acquisitions.

To ease acquisition of the required number of lines we recommend to set the line start trigger

mode to off for automatic line start triggering and to set the Height parameter for the frame to at

least 128.

For more information about the line start trigger mode, see Section 8.2.4 on page 87.

For more information about defining a frame, see Section 8.1 on page 75.

Creating a "usershading" file for gain shading correction will overwrite any

"usershading" file for gain shading correction that is already in the camera’s

memory.

If you want to preserve the previous "usershading" file save it to your PC before

creating the new "usershading" file.

For information about saving a "usershading" file to the PC, see Section 10.8.3.2

on page 183.

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Basler raL2048-48gm User Manual Page 192