Shading Compensation (Sdm) - JAI AT-200CL User Manual

7.2.5 Shading compensation (SDM)

The AT-200CL 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%.
Shading correction mode: SDM
0:OFF, 1:Factory shading, 2:User 1, 3:User2
These are used to load the stored data.
In order to calibrate the shading, use RS command, Recalibrate Shading correction.
Param. 1 is used to store the calibration data in 0 for User 1 and 1 for User 2. User 1 and User
2 can store only one data set for either color shading or flat shading. Param. 2 can be set to
0 for Flat or 1 for Color and executes the shading correction and the storing of data.
Note: Conditions for lens used with AT-200CL
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.
AT-200CL 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.18 Conceptual drawing for color shading compensation
2. Flat shading compensation
In this mode, each channel can be adjusted to achieve flat characteristics.
Fig.19 Conceptual drawing for flat shading compensation
AT-200CL
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Fig.17 Shading compensation