Dalsa Piranha4 User Manual page 50

Video
Calibrate FPN
flatfieldCalibrationFPN
(ccf)
1. Flat Field
This Flat Field set contains a number of features that are used to correct image distortion due to lens
vignetting and uneven illumination. .
Note:
1. Flat field coefficients consist of an offset and gain for each pixel.
2. These are the first user corrections applied to the image.
3. The flat field coefficients are saved and loaded with the user set.
Parameter
flatfieldCorrectionMode
flatfieldCorrectionAlgorithm
flatfieldCalibrationTarget
flatfieldCalibrationSampleSize
flatfieldCalibrationROIOffsetX
flatfieldCalibrationROIWidth
Calibrate
PRNU
flatfieldCorrectionMode
flatfieldCalibrationPRNU
flatfieldCorrectionAlgorithm
(cpa,ffm)
Figure 26: Camera Calibration Process.
1. Off – Flat field correction coefficients are not applied.
2. On – Flat field correction coefficients are applied.
3. Initialize – Sending this value will reset all current coefficients
(offsets to 0 and gains to 1x).
1. Basic – Direct calculation of coefficients based on current
average line values and target.
2. LowPass – A low pass filter is first applied to the current
average line values before calculating the coefficients. Use this
algorithm if the calibration target is not uniform white or it s
not possible to defocus the image. Because of the low pass filter
this algorithm is not able to correct pixel-to-pixel variations and
so it is preferable to use the "Basic" algorithm if possible.
1. After calibration all pixels will be scaled to output this level
2. Range depends on pixel format:
•
8 bit: 0 to 255 DN
•
10 bit: 0 to 1023 DN
•
12 bit: 0 to 4095 DN
1. Number of lines to average when calibrating
2. 2048 or 4096
1. Together with "flatfieldCalibrationROIWidth" specifies the
range of pixels to be calibrated. Pixel coefficients outside this
range are not changed. It is possible to calibrate different
regions sequentially.
Filter Threshold
ImageEnhancementStrength
(sft)
Description
-
+
Offset
Gain
Gain
BlackLevel
(ssg)
(ssb)
Output
Video