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the full scale. The offset is always entered as a 12-bit number, which means that if you have
set the camera for one of the 8-bit output modes, you should multiply the intended offset shift
by 16 to get the offset for this command.
Please keep in mind that this command changes the digital output signal level just before the
gain factor is applied. A positive number raises the output levels, while negative numbers drop
the levels being though limited to zero.
7.2.7
FFC
– flat field correction
The function of the Flat Field Correction (FFC) is to compensate for differences in the optical
input. This can be shading due to lower transmission at the lens sides or similar optical
corrections. The Flat Field Correction must be done when the input light distribution is as
uniform as possible in order not to make the FFC correction add errors to the compensation
when activated.
The procedure is then to establish a scene illumination as uniform as possible and having the
intended optics for the application before saving the FFC line graph for the correction. A
uniform test target is needed. It is recommended to calibrate the correction slightly off focal.
This can be achieved either by changing the viewing distance (recommended option) or by
turning the lens a little off the best focus. The correction must be OFF during calibration.
Command
Description
FFC ?
Returns the FFC command syntax
FFC
Shows whether the correction is ON of OFF.
FFC RUN
When FFC RUN is sent to the camera the actual line image will be
corrected to make the line as horizontal as possible.
FFC ON
Activates the FFC function. If no line graph is saved prior to
activation of the FFC function then no change will be made to the
line image.
FFC OFF
Switches the FFC function OFF. FFC ON command returns the same
correction factors into use, unless a new FFC SAVE command was
given. Default setting.
