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Description of the data path
OSCAR Technical Manual V2.4.0
74
Shading correction
Shading correction is used to compensate for non-homogeneities caused by
lighting or optical characteristics within specified ranges.
To correct a frame, a multiplier from 1...2 is calculated for each pixel in 1/
256 steps. This allows for shading to be compensated by up to 50%.
Besides generating shading data off-line and downloading it to the camera,
the camera allows correction data to be generated automatically in the cam-
era itself.
The following pictures describe the process of automatic generation of cor-
rection data. The line profiles were created using MVTEC's ActivVision Tools.
On the left you see the source image with non-uniform illumination. The
graph on the right clearly shows the brightness level falling off to the right.
By defocusing the lens, high-frequency image data are removed from the
source image, therefore its not included in the shading image.
Note
L
• Shading correction does not support the mirror func-
tion.
• If you use shading correction, don’t change the mirror
function.
Figure 32: Shading correction: Source image with non-uniform illumination