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OPERATING AND USER MANUAL QUARTZ SERIES
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Flat field correction 8.3
Introduction 8.3.1.
The pixels of the CMOS sensor show offset and gain variations in their response to light.
In the Quartz cameras, these deviations are per-pixel corrected for.
The offset correction is referred to as dark field correction. •
The gain correction is referred to as bright field correction. It comes in two flavours, local and •
global.
In local flat field gain correction, a particular pixel is ‘flat fielded’ with respect to it’s near
environment.
In globel flat field gain correction, the entire image is ‘flat fielded’ towards the same response (this
can be used to compensate for e.g. shading due to optics).
The offset and local gain flat field corrections are pre-calibrated in the factory. The user is able to do
recalibrate in the field. Calibrations may take up to several seconds.
Up to 4 gain calibrations may be saved for use.
Enable/disable flat field corrections 8.3.2.
Offset and gain corrections may be enabled or disabled. Furthermore, for gain corrections local or
global correction may be applied. In local gain correction a particular pixel is ‘flat fielded’ with respect
to it’s near environment. In global gain correction the entire image is ‘flat fielded’ towards the same
response
Command format: FFPn;x
Command format: FFP?n
Return Message: n
Where n indicates the parameter number and x the value of the parameter.
For clarity, the dark field related parameters start at 0 and all gain related parameters at 100.
N RANGE X DESCRIPTION
0 0,1 Disable (x=0) or enable (x=1) dark field fixed pattern (offset) correction.
100 0,1 Disable (x=0) or enable (x=1) gain correction.
101 0,1 Local (x=0) or global (x=1) gain correction.
102 0,1 Disable (x=0) or enable (x=1) automatic exposure adjustment during gain
calibrations.
Settings 101 and 102 are related to the calibration of the corrections and do not play a role during
operation of the camera (see section 8.3.5).
Gain flat field calibration set selection 8.3.3.
There are 4 gain calibrations storable. This enables storing various sets for e.g. various optics.
Selection of the calibration used can be configured by the command:
Command format: FFSELn
Where n = 0…4.
For 1
≤
n
≤
4, the indicated set n is selected.