[filmscanners] Re: Density vs Dynamic range

["" <peter@softwell.co.uk>]

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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