Dalsa Spyder3 User Manual page 48

48
PRNU Correction
Performing PRNU to a user entered value
Purpose:
Syntax:
Syntax Elements:
Notes:
Example:
Subtracting Background
Purpose:
Syntax:
Syntax Elements:
03-032-20059-01
Performs PRNU calibration to user entered value and eliminates the
difference in responsivity between the most and least sensitive pixel,
creating a uniform response to light. Using this command, you must
provide a calibration target.
Executing these algorithms causes the ssb command to be set to 0
(no background subtraction) and the ssg command to 4096 (unity
digital gain). The pixel coefficients are disabled (epc 0 0) during
the algorithm execution but returned to the state they were in prior
to command execution.
cpa i i
i
PRNU calibration algorithm to use:
2 = Calculates the PRNU coefficients using the entered target
value as shown below:
PRNU Coefficient =
i
The calculation is performed for all sensor pixels but warnings
are only applied to pixels in the region of interest. This
algorithm is useful for achieving uniform output across multiple
cameras. It is important that the target value (set with the next
parameter) is set to be at least equal to the highest pixel across
all cameras so that all pixels can reach the highest pixel value
during calibration.
i
Peak target value in a range from 1024 to 4055DN. The target
value must be greater than the current peak output value.

Perform all analog adjustments before calibrating PRNU.

Calibrate FPN before calibrating PRNU. If you are not
performing FPN calibration then issue the
coefficients) command.
cpa 1 600
Use the background subtract command after performing flat field
correction if you want to improve your image in a low contrast
scene. It is useful for systems that process 8 bit data but want to
take advantage of the camera's 12 bit digital processing chain.
You should try to make your darkest pixel in the scene equal to
zero.
ssb i
i
Subtracted value in a range in DN from 0 to 4095.
Spyder3 Color Manual
Target
(AVG Pixel Value )
i
(reset pixel
rpc
DALSA