35
Piranha2 User’s Manual
To calibrate the analog gain:
Syntax:
cag t i
Syntax Elements:
t
Tap selection. Allowable range is 1 to 4, or 0 for all taps.
i
Line average in a range dependent on the current camera
data mode setting:
8-bit: 64 to 251 DN
10 bit: 256 to 1007 DN
See section 3.11 Returning Video Information for more
information on line averages
Notes:
•
This function requires constant light input while executing.
•
This command sets gain in
uncalibrated
mode.
Related Commands:
gla, gl
Example:
cag 1 156
3.14
How to Calibrate the Camera
Calibration Overview
This camera has the ability to calibrate itself 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
The two point correction is implemented such that for each pixel:
V
output
= (V
input
- FPN( pixel ) - digital offset) * PRNU(pixel)
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
The calibration 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 output when the CCD is not
exposed.
03-32-00493-11
DALSA
