
Piranha Color Camera
41
Example:
sao 2 35
Related Commands:
cao
3.15 Flat Field Correction
Flat Field Correction Overview
This camera has the ability to calculate correction coefficients in order to remove non-
uniformity in the image. This video correction operates on a pixel-by-pixel basis and
implements a two point correction for each pixel. This correction can reduce or
eliminate image distortion caused by the following factors:
Fixed Pattern Noise (FPN)
Photo Response Non Uniformity (PRNU)
Lens and light source non-uniformity Correction is implemented such that for each
pixel:
Analog Processing
Digital Processing
analog video
analog
gain
analog
offset
FPN
coefficients
digital
offset
PRNU
coefficients
background
subtract
digital system
gain
sag,ccg
sao
ccf
sdo
ccp,cpa
ssb
ssg
background
addition
digital video
sab
background
addition
digital video
eil
LUT
addition
V
output
=[(V
input
- FPN( pixel ) - digital offset) * PRNU(pixel)
–
Background Subtract] x
System Gain + Background Addition
where
V
output
=
digital output pixel value
V
input
=
digital input pixel value from the CCD
PRNU( pixel)
=
PRNU correction coefficient for this pixel
FPN( pixel )
=
FPN correction coefficient for this pixel
Background Subtract
=
background subtract value
System Gain
=
digital gain value
Background Addition
=
background addition value
The algorithm is performed in two steps. The fixed offset (FPN) is determined first by
performing a calibration without any light. This calibration determines exactly how
much offset to subtract per pixel in order to obtain flat (zero) output when the CCD is
not exposed.
The white light calibration is performed next to determine the multiplication factors
required to bring each pixel to the required value (target) for flat, white output. Video
output is set slightly above the brightest pixel (depending on offset subtracted).
Note:
If your
illumination
or white
reference
does not
extend the
full field of
view of the
camera, the
camera will
send a
warning.
Содержание DALSA Piranha PC-30-02K60-00-R
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