Dalsa Falcon 4-CLHS Series, User Manual

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34 • Operational Reference Falcon™ 4 -CLHS Series
FPN Correction
The fixed pattern noise (FPN) correction compensates for dark current noise unique to each camera
sensor.
The Falcon4 uses 2 stages of FPN correction:
• Row-by-row dark current correction using values generated with shielded reference pixels
(Optical Black Reference and Optical Black Reference Calibration Offset features).
• ADC noise correction
Both stages can be enabled and disabled independently. The FPN Correction Mode, along with the
Optical Black Reference enable state during calibration, determine which FPN correction are
applied. When the Optical Black Reference feature is set to Active, during calibration these
correction coefficients are generated and are always applied.
Optical Black Reference
(during calibration)
FPN Correction Mode Result
Active Off Only Optical Black Reference correction applied.
(ADC correction disabled).
Active Both Optical Black Reference and ADC correction applied.
Off Off No FPN correction applied.
Active Only ADC correction applied.
FPN calibration is always performed using 10-bits (regardless whether the Pixel Format is set to 8
or 10-bit)
With CMOS sensors, it is important to perform FPN calibration under the same operating conditions
the camera will be used, otherwise sensor variations (over temperature and exposure) will make
the FPN calibration invalid.
Falcon4 cameras has two FPN user memory spaces to store calibration data, allowing users to store
FPN data for different optimized exposure setups. A user set can store coefficients for specific gain
settings (gain = 1, 1.5, 2.0, 2.5, 3.0, 3.5 and 4); a calibration must be performed with each gain
setting and saved to the same user set (gain settings which are not user calibrated use the factory
default).