Falcon2 4M, 8M, and 12M Camera User's Manual
101
Teledyne DALSA
03-032-20107-03
o
Calcu late the m u ltip lication factor necessary to achieve the target valu e. The target valu e
is calcu lated u sing
flatfieldCalibrationTarget.
See Figu re 38.
Figure 38 Monochrome Flat Field Gain Calibration
o
If the calcu lated gain is less than 1 then the nu m ber of clip p ed gain p ixels
(
flatfieldCalibrationGainPixelsClipped)
is increm ented . A large nu m ber of clip p ed p ixels
m ay ind icate a p oorly ch osen target or exp osu re setting.
o
If the calcu lated p ixel gain is greater than the p ixel rep lacem ent threshold (see
flatfieldCalibrationPixelReplacementGainThreshold
) then the p ixel is m arked for rep lacem ent
and the nu m ber of d ead p ixels rep lace is increm ented
(
flatfieldCalibrationDeadPixelsReplaced
). These p ixels w ill have the m axim u m gain
correction bu t w ill not reach the target. By d efau lt the rep lacem ent threshold is set to the
highest correctable valu e so that the nu m ber of d ead p ixels that are not rep laced is 0.
o
If the calcu lated p ixel gain is not correctable (i.e. greater than 1.5 or 2 w hen
flatfieldCalibrationGainM ode is HighResolution or
HighGain
) bu t less than the rep lacem ent
threshold then the gain is set to m axim u m and the nu m ber
of d ead p ixels not rep laced is
increm ented (
flatfieldCalibrationDeadPixelsN otReplaced)
Once the gain valu es are calcu lated , the valu es are u sed to correct the im age .
For the color cam eras, the p rocess is sim ilar w ith the excep tion of the target valu e. For co lor cam eras each
color has its ow n target based on the average of each color m u ltip lied by a factor (ap p rox. 1.25). After
each color is corrected the color gains are ad ju sted to set the p ixels to the m axim u m color.
Target
ADC
Pixel
xy
PRNU
xy
Multiplier
Clipped Gain
Correctable
1
“Dead” Pixels
NOT Replaced
0
1.5
or
2.0
(See
flatfieldCalibrationGainMode
)
(
flatfieldCalibration
PixelReplacement
GainThreshold
)
“Dead” Pixels Replaced
Calibrated Flat Field Gain Values
Gain(PRNU)
