Spyder3 S3-14 and S3-24 Monochrome Camera User's Manual
53
Teledyne DALSA
03-032-20117-01
Calibration Overview
When a cam era im ages a u niform ly lit field , id eally, all of the p ixels w ill have the sam e gray valu e.
H ow ever, in p ractice, this is rarely the case (see exam p le below ) as a nu m ber of factors can contribu te to
gray scale non -u niform ity in an im age: Lighting non -u niform ities and lens d istortion, PRN U (p ixel
resp onse non-u niform ity) in the im ager, FPN (fixed p att ern noise) in the im ager, etc.
Figure 27. Image with non-uniformities
By calibrating the cam era you can elim inate the sm all gain d ifference betw een p ixels and com p en sate for light
d istortion. This calibration em p loys a tw o-p oint correction that is ap p lied to the raw valu e of each p ixel so that
non-u niform ities are flattened ou t. The resp onse of each p ixel w ill ap p ear to be virtu ally id entical to that of all
the other p ixels of the sen sor for an equ al am ou nt of exp osu re.
Calibration Steps
Step 1: Preparing for Calibration
If you d o not w ant to change the cu rrent cam era settings, bu t w ant to calibrate the cam era, skip this step and
m ove to Step 2: PRN U Calibration.
To check the cu rrent cam era settings, u se the get cam era p aram eters (gcp ) or the get com m and s. You can
change som e or all of the follow ing settings before calibrating:
Set exp osu re m od e u sing the com m and sem m , w here m = 2/ 3/ 4/ / 6
For exam p le,
sem 2
Set line sync frequ ency (line rate) u sing the com m an d ssf f, w here f = - 72 kH z
For exam p le,
ssf 5000
Set exp osu re tim e u sing the com m and set f, w here f = 1 - 8888 µs in an available m od e.
For exam p le,
set 100
Set gain u sing com m and sg t i, w here t are the tap s 0 to 21 and i = ± 24 d b
For exam p le,
sg t 0
Save u ser settings u sing com m and
wus
.
A N ote on FPN or D ark Calibration
FPN calibration (also called d ark calibration) is d one in the factory.
Step 2: PRN U or White Calibration
1. Rem ove the lens cap an d p rep are a w hite, u niform target.
2. Ad ju st the line rate so that the aver age ou tp u t is abou t 80% of the fu ll ou tp u t, or below the PRN U target
valu e by:
Ad ju sting the lighting, if you are u sing an intern al exp osu re m od e. Or,
Ad ju sting the line rate, if you are u sing the Sm art Exsync m od e.
3. Calibrate the PRN U u sing the com m and
cpa 2 i,
w here 2 is the PRN U calcu lated u sing the entered target
valu e as sh ow n in the form u la on p age 56 and i is the target valu e and the valu e of i is 1024 to 4055 DN .
For exam p le: cp a 2 3300
