56
Spyder3 S3-14 and S3-24 Monochrome Camera User's Manual
03-032-20117-01
Teledyne DALSA
PRNU Correction
Perform s PRN U calibration to u ser entered valu e and elim inates the d ifference in resp onsivity betw een the m ost and
least sensitive p ixel, creating a u niform resp onse to light. Using this com m and , you m u st p rovid e a calibration target.
Execu ting these algorithm s cau ses the
ssb
com m and to be set to
0
(no backgrou nd su btraction) and the
ssg
com m and to
4096
(u nity d igital gain). The p ixel coefficients are d isabled (
epc 0 0
) d u ring the
algorithm execu tion bu t retu rned to the state they w ere in p rior to com m and execu tion.
Camera Link Command
Parameter
Description
Notes
cp a i i
i:
PRN U calibration algorithm to u se:
1
= This algorithm first ad ju sts each tap ’s analog gain so that 8-
13% of p ixels w ithin a tap are above the valu e sp ecified in the
target valu e p aram eter. PRN U calibration then occu rs u sing the
p eak p ixel in the region of interest.
This algorithm is recom m en d ed for u se only w hen FPN is
negligible and FPN coefficients are set to zero. Since this algorithm
ad ju sts the analog gain, it also affects FPN . If FPN is calibrated
p rior to ru nning this algorithm , FPN w ill be observable in d ark
cond itions and an incorrect FPN valu e w ill be u sed d u ring PRN U
calibration resu lting in incorrect PRN U coefficients.
2
= Calcu lates the PRN U coefficients u sing the entered target
valu e as show n below :
The calcu lation is p erform ed for all sensor p ixels bu t w arnings are
only ap p lied to p ixels in the region of interest. This algorithm is
u sefu l for achieving uniform ou tp u t across m u ltip le cam eras. It is
im p ortant that the target valu e (set w ith the next p aram eter) is set
to be at least equ al to the highest p ixel across all cam eras so that
all p ixels can reach the highest p ixel valu e d u ring calibration.
3
= This algorithm inclu d es an analog gain ad ju stm ent p rior to
PRN U calibration. Analog gain is first ad ju sted so that the peak
p ixel valu e in the tap ’s ROI is w ithin 97% to 99% of the sp ecified
target valu e. It then calcu lates the PRN U coefficients u sing the
target valu e as show n below :
The calcu lation is p erform ed for all sensor p ixels bu t w arnings are
only ap p lied to p ixels in the region of interest. This algorithm is
u sefu l for achieving uniform ou tp u t across m u ltip le cam eras.
This algorithm is u sefu l for achieving u niform ou tp u t across
m u ltip le cam eras by first ad ju sting analog gain and then
p erform ing PRN U calibration. This algorithm is recom m end ed for
u se only w hen FPN is negligible and FPN coefficients are set to
zero. Since this algorithm ad justs the analog gain, it also affects
FPN . If FPN is calibrated p rior to ru nning this algorithm , FPN w ill
be observable in d ark cond itions and an incorrect FPN valu e w ill
be u sed d u ring PRN U calibration resu lting in incorrect PRN U
coefficients.
This algorithm is m ore robu st and rep eatable than algorithm 1
becau se it u ses an average p ixel valu e rather than a nu m ber above
Perform all analog
ad ju stm ents before
calibrating PRN U.
This com m and
p erform s the sam e
fu nction as the
cpp
com m and bu t forces
you to enter a target
valu e.
Calibrate FPN before
calibrating PRN U. If
you are not p erform ing
FPN calibration then
issu e the
rpc
(reset p ixel
coefficients) com m and
and set the
sdo
(set
d igital offset) valu e so
that the ou tp u t is near
zero u nd er d ark.
PRNU Coefficient =
Target
(AVG Pixel Value ) - (FPN +
value)
sdo
i
i
i
PRNU Coefficient =
Target
(AVG Pixel Value ) - (FPN +
value)
sdo
i
i
i
