JAI AT-140GE - Manual (Page 34)

AT-140GE
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9.4. Pre-processing functions
9.4.1 Shading compensation
The AT-140GE implements a digital shading compensation
circuit for the white shading which could be caused in the
prism or optical system. The whole image is divided
horizontally and vertically and uses the center level as the
reference. The circuit will compensate the difference between
the center and each divided area. The range for compensation
is a maximum of 30%. In the factory, the shading compensation
is done under the following conditions and stored in the
“Factory” area of the memory.
Lens used: Kowa 12mm F1.8 to F16
F value: F5.6
Note: Conditions for lens used with AT-140GE
In order to get an appropriate picture, it is recommended to use 1/2 inch, 3CCD lenses.
Shading is dependent on F value and focal length. Using a wide angle lens or using the
lens fully open, will cause the shading characteristics to deteriorate.
The AT-140GE has two shading compensation circuits.
1. Color shading compensation
In this mode, the shading is compensated using the G channel as the reference.
Adjust R and B channels to match the characteristics of the G channel. Use white balance
to match R, G and B levels.
Fig.27 Conceptual drawing for color shading compensation
2. Flat shading compensation
In this mode, each channel can be adjusted to achieve flat characteristics.
Fig.28 Conceptual drawing for flat shading compensation
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Fig.26 Shading compensation