Linea Lite GigE Series Camera
Camera Performance and Features
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Flat Field Correction
The Flat Field Correction function (FFC) consists of using two coefficients per pixel which correct the
gain and offset of the corresponding pixel. These corrections compensate for Photo-Response Non-
Uniformity (PRNU) and Fixed Pattern Noise (FPN) unique to each camera sensor.
With CMOS sensors, it is important to perform FFC calibration under the same operating conditions
that the camera is to use, otherwise sensor variations (over temperature and exposure) will make
the FFC calibration invalid. Linea Lite GigE cameras have multiple FFC user memory spaces to store
calibration data, allowing users to store FFC data for different optimized exposure setups.
The following diagram illustrates the camera’s digital processing chain and associated GenICam
features.
Image
Output
Image
Digital Processing
(monochrome
)
FPN
Correction
PRNU
Correction
Offset
Gain
To calibrate FPN
:
Features: flatfieldCorrectionMode
fflatfieldCalibrationSampleSize
flatfieldCalibrationFPN
To calibrate PRNU
:
Features:
flatfieldCorrectionMode
flatfieldCalibrationSampleSize
flatfieldCalibrationPRNU
flatfieldCorrectionAlgorithm
flatfieldCorrectionTarget
-
X
-/+
X
To set Back Level offset:
Features:
BlackLevel
To set Gain:
Features:
Gain
Flat Field Correction Algorithm Description
Flat Field Correction Algorithm
–
Method1 (
) applies the following FFC
formula for correcting pixel values.
newPixelValue[x] = (sensorPixelValue[x] - FFCOffset[x]) * FFCGain[x]
where:
•
[
x
] is the Flat Field Correction Pixel coordinate.
flatfieldCorrectionPixelXCoordinate
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newPixelValue
is the pixel value after Flat Field Correction is applied.
•
sensorPixelValue
is the pixel value before Flat Field correction is applied.
•
FFCOffset
is the offset coefficient value to subtract from the sensorPixelValue.
•
FFCGain
is the gain coefficient value that is multiplied with the sensorPixelValue.
Important:
FFCOffset and FFCGain are derived factors calculated from a number of
camera specific feature values (Invisible DFNC features).
Note
: Reading these values directly from the Flat Field Coefficients file will be
meaningless to the user.
Preliminary