Piranha Color Camera User’s Manual 37
DALSA 03-032-10211-01 5/9/2007
Example:
sah 2
3.13 Processing Chain Overview and
Description
The following diagram shows a simplified block diagram of the camera’s analog and
digital processing chain. The analog processing chain begins with an analog gain
adjustment, followed by an analog offset adjustment. These adjustments are applied to
the video analog signal prior to its digitization by an A/D converter.
The digital processing chain contains the spatial correction, non-linearity look-up table
(LUT) correction, FPN correction, the PRNU correction, the background subtract, the
digital gain, and the background add. All of these elements are user programmable.
Figure 7: Signal Processing Chain
Analog Processing
Digital Processing
analo gvideo
ana log
gain
analog
offset
FPN
coefficients
dig i tal
offset
PRNU
coefficients
background
subtr act
digitalsys tem
gain
sag,ccg
sao
ccf
sdo
ccp,cpa ssb
ssg
background
addition
digitalvideo
sab
background
addition
digitalvideo
eil
LU T
addition
Analog Processing
Optimizing offset performance and gain in the analog domain allows you to achieve
a better signal-to-noise ratio and dynamic range use. Perform all analog adjustments
prior to any digital adjustments.
Analog gain (
sag or ccg command) is multiplied by the analog signal to increase
the signal strength before the A/D conversion (and before noise is added to the
signal).
The analog offset (
sao command) or black level is an “artificial” offset introduced
into the video path to ensure that the A/D is functioning properly. The analog
offset should be set so that it is at least 3 times the RMS noise value at the current
gain.
Digital Processing
To optimize camera performance, complete all analog adjustments before digital
signal adjustments.
Fixed pattern noise (FPN) calibration (calculated using the ccf command) is used
to subtract away individual pixel dark current.
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