AGFA d-lab.3 Digital Compact Lab

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Repair
Concept of the CCD Signal Processing
In order to improve the noise distance, the so-called
CDS method (Correlated Double Sampling) is used:
There is not only the actual pixel value for each
pixel, but also a dark reference which takes into
account local differences of the PRNU. PRNU are
pixel-dependent voltage differences which do not
depend on the time and the light.
The two signals are found by a special CDS chip
which exists separately for each quadrant of the
CCD chip. The difference between these two signals
is the output signal.
The CCD chip comprises 6 additional lines per
quadrant whose pixels are not active electrically.
The average value of their contents serves as
parameter to check the temperature or the dark
current.
Frosted Glass for Pixel Correction (Piko)
A frosted glass is mounted in addition in the mobile
pallet of the auxiliary shutter (dust shutter for the
lens).
− It is used for the calculation of the parameters
needed for the multiplicative pixel correction.
− It should ensure an optimum homogeneous and
dustfree illumination.
4.3.22 2001-01-02 /PN 9009 AGFA d-lab.3