Naah - take two tsp of Rodinol and call me in the morning
> OY ... I think I need a Bayer aspirin ...
>
> Nenad Djurdjevic wrote:
> >
> > Jostein wrote:
> >
> > > Please someone correct me if I have got this wrong; I'm going to attempt a
> > > coherent (don't laugh) description of my own understanding here...
> > >
> > > IMO, the number of pixels can be considered to be a function of
> > > 1. the properties of the CCD used to capture the light, and
> > > 2. the software to interprete the captured data.
> > >
> > > I'm not sure I know all the properties involved, but at least there is the
> > > number of physical pixels, and their size (density), and the Bayer
> > algorithm
> > > involved to reconstruct a colour image from the physical pixels.
> > >
> > > To consider a 35mm equivalent, assume a 36x24mm CCD. How many pixels do we
> > have
> > > to put into a 36x24mm CCD to match the resolution power of a film?
> > >
> > > For simplicity, let's assume that this is equal to the size of film grains
> > that
> > > we can measure in a microscope. When that is known (i haven't got the
> > > number...), we can compare that to the pixel size on the chip. I am pretty
> > sure
> > > that eg. Provia 100F grain size is smaller than current pixel size in eg.
> > > *istD.
> > >
> > > And here's a problem; there is a physical limit to how small pixels can be
> > > before they start to behave erratically. The size used in the *istD is
> > thought
> > > to be quite optimal, if I have understood this right.
> > >
> > > If the above is correct, the optimal 36x24mm CCD is one with approximately
> > the
> > > same pixel density as the *istD has, which would amount to ca. 14
> > Megapixels.
> > >
> > > I don't know if 14 Megapixels in 36x24mm is even close to the grain size
> > of
> > > ProviaF, but let's assume that it was...:-)
> > >
> > > Those 14 Mpix must be subjectet to Bayer interpolation before we can see a
> > true
> > > RGB image. The interpolation will tend to smooth out details that are
> > smaller
> > > than the smallest cluster of pixels used in the interpolation. I'm not
> > sure
> > > exatly how this affects the final image quality, but I suspect that this
> > is the
> > > reason why skin tones and blue skies look smoother with digital, while
> > grassy
> > > fields or tree branches and twigs look smeared out. Especially in
> > low-contrast
> > > situations.
> > >
> > > So, even if 14 Mpix was equivalent to film grain number, CCDs would be
> > less able
> > > to hold detail (I think this is where the Foveon concept excels over Bayer
> > > interpolation).
> > >
> > > This means that you would need more pixels per area than you have film
> > grain per
> > > area to record the same level of detail. If film grains can be made
> > smaller
> > > than CCD pixels, film will win hands down. And that's no matter what
> > format you
> > > compare.
> > >
> > > Another discussion is whether the lenses exist to give you full value for
> > either
> > > recording media. If the practical resolving power is less than pixel/grain
> > > density, the difference between film and CCDs is suddenly not _that_
> > important
> > > any more.
> > >
> > >
> > > So Nenad,
> > > I'm not at all sure I know any better than you, I'd rather learn than
> > teach. I'm
> > > just testing my own grip...:-)
> > >
> > > Cheers,
> > > Jostein
> > >
> > You're too modest Jostein! You've put together a very coherent and logical
> > analysis.
> >
> > Regards
> > Nenad
>
