Tony wrote:
> I don't know Fuji's estimation method, but, like Kodak, they probably
> use an arbitrary visual scale for grain relative to a reference
> standard. In which case the numbers will not be microns or any
> convertible unit.
Ah, well. Then it's only meaningful as a relative comparison within
films of the same brand. Anyway, the reason I posted about the pixel
size was to see if anyone had any actual figures on grain size for
a comparison.
>The only grains which you can rely on not to cause aliasing are those
>whose dimensions are at least 2x pixel size (Nyquist), and in practice
>perhaps quite a lot bigger because of higher-frequency topographical
>variations such as irregular shape/edges.
OK, so how does that gel with my experience that the only film which
has scanned with *no* visible grain or noise of any kind is Provia
100F which has the finest grain of anything I've tried? By your
statement above, it should demonstrate aliasing. I'd suggest that
the finer grain produces the best result because the CCD is then
effectively averaging the colours of many dye clouds, just as using
the size reduction function in Vuescan gives less grainy results
by averaging actual samples.
>[snip] but suck it and see observation seems to avoid a lot of
>tail-chasing.
Which is precisely why I'm taking the approach I have.
> So here's another example of me making simple things
> complicated again..
Actually I read it as "looking at the result is the only
meaningful method open to us", and that's what I want to
do.
The issues are useful to know, however. Thanks!
Rob
Rob Geraghty [EMAIL PROTECTED]
http://wordweb.com
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