Baumer EXG03 - Pixel Correction; General Information; Correction Algorithm

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4.5 PixelCorrection
4.5.1 Generalinformation
A certain probability for abnormal pixels - the so-called defect pixels - applies to the sen-
sors of all manufacturers. The charge quantity on these pixels is not linear-dependent on
the exposure time.
The occurrence of these defect pixels is unavoidable and intrinsic to the manufacturing
and aging process of the sensors.
The operation of the camera is not affected by these pixels. They only appear as brighter
(warm pixel) or darker (cold pixel) spot in the recorded image.
Warm Pixel
Cold Pixel
Charge quantity
„Normal Pixel“
Charge quantity
„Cold Pixel“
Charge quantity
„Warm Pixel“
4.5.2 CorrectionAlgorithm
On monochrome cameras of the Baumer EXG series, the problem of defect pixels is
solved as follows:
▪ Possible defect pixels are identied during the production process of the camera.
▪ The coordinates of these pixels are stored in the factory settings of the camera (see
4�5�3� Defectpixellist).
▪ Once the sensor readout is completed, correction takes place:
▪ Before any other processing, the values of the two neighboring pixels on the left and
the right side of the defect pixel, will be read out
▪ Then the average value of these 4 pixels is determined
▪ Finally, the value of the defect pixel is substituted by the previously determined
average value
Defect Pixel Average Value Corrected Pixel
Figure27►
Distinction of "hot" and
"cold" pixels within the
recorded image.
Figure28►
Charge quantity of "hot"
and "cold" pixels com-
pared with "normal"
pixels.
Figure29►
Schematic diagram of
the Baumer pixel
correction.