Chuck,
> > There are LUTs (Look-Up Tables) in the scanner that compensate for the
> > non-linearities that are determined during calibration. These are
simply
> > offset values that are added/subtracted from the actual data values.
> That is likely,
Likely? It's what scanners go through a calibration sequence for!
> but the table values would be offsets and not mathematical
> non-linearities per se.
They absolutely are to correct for non-linearities, and addition (which is
what an offset is) IS how you correct for non-linearity in a system like
this.
> > Basically, they simply count photons, and the output is directly
> > proportional to the number of photons counted.
> These do not count photons except in the gross aggregate where the actual
> count is unknowable.
They DO in fact "count" photons. The voltage output is DIRECTLY LINEARLY
proportional to the number of photons that the sensor detects. Go read a
CCD spec and you'll see this to be true.
> > > Nearly all non-linearities and most noise effects are introduced
> > > after the detectors and are minimal effects.
>
> > Hum. I disagree with that. You aren't taking into account
> > non-linearities across sensor elements.
> That is not a mathematical non-linearity at all: it's only a linear
offset.
The statement I commented on is incorrect, for the reason I said. The
sensor non-linearities ARE a mathematical non-linearity, addition is
mathemeatical, and yes it is simply an offset, which is addition, and
addition is mathematical. I'm not sure what the distinction/point you are
trying to make here is.
Regards,
Austin
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