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[filmscanners] Re: Density vs Dynamic range



As this agrees with my engineering understanding, and not the strange
figures that the scanning industry have been kicking around I'm going to
say no more on this.

I suspect my "discussions" with Austin have been unnecessarily prolonged
by his adherence to these non-engineering standards.

> Yeah, but Dickbo...obviously you don't understand what it means.  It's
> got
> errors in it...but corrected, it's saying exactly what I've been saying.
> Like I said, you just don't understand this stuff, and don't want to.
>
> Austin
>
>
> > -----Original Message-----
> > ... I'd like to follow this through to a definitive source.
> > >
> >
> > The proposed ISO standard on "Photography - Electronic scanners for
> > photographic images - Dynamic range measurements" (WD 21550.3 (42N
> > 4909))
> > states that the dynamic range is calculated by:
> >
> > DR = Dmax - Dmin
> > DR = Scanner dynamic range
> > Dmax = Density where the signal to noise ratio is 1
> > Dmin - Minimum density where the output signal of the luminance OECF
> > (opto-electronic conversion function) appears to be unclipped
> >
> > They go on to define a standard method for defining the signal to
> > noise
> > ratio using the concept of incremental gain.  Incremental gain allows
> > the
> > signal to noise ratio to be determined independent of gamma.
>


Peter, Nr Clonakilty, Co Cork, Ireland

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